CN111472722B - Method and device for predicting layered gas production capacity of coal bed gas co-production well - Google Patents

Abstract

The application discloses a method and a device for predicting layered gas production capacity of a coalbed methane co-production well, and belongs to the technical field of coalbed methane development and drainage and production. According to the technical scheme, the gas production capacity of each layer can be judged before gas production of the coal-bed gas well based on the actual production parameters of each well, a basis is provided for formulation of the gas production rate of the coal-bed gas well, such as the stable gas production rate, the stable production pressure and the like, and the gas production capacity is judged according to the actual production parameters of each well, so that adverse effects of coal-bed plane heterogeneity on a prediction result can be effectively avoided, the prediction accuracy is greatly improved, the prediction process does not need a large amount of geological parameters and high-depth geological knowledge, the operation is simple and convenient, the method is simple, the requirement on the user capacity is low, the method is suitable for large-scale field popularization, and the method can be popularized and applied to all coal-bed gas wells which are combined to be mined more than two layers.

Description

Method and device for predicting layered gas production capacity of coal bed gas co-production well

Technical Field

The application relates to the technical field of coal bed gas development and drainage and production, in particular to a method and a device for predicting the layered gas production capacity of a coal bed gas co-production well.

Background

The main coal bed gas reservoir in the south of the Qin basin is 3^#Coal seam and 15^#Coal seam, in order to improve single well output and reduce development cost, a single well drilling through 15 is generally adopted^#Coal seam, using 3^#Coal seam and 15^#And developing a partial pressure combined mining mode of the coal bed. Because of the strong plane heterogeneity of the coal reservoir, the situation that the contribution of the yield of the lower layer or the upper layer is extremely low may occur in the double-layer combined production well, but because the two layers are simultaneously produced, the yield is combined into one, and the gas production capacity of each layer cannot be judged. The judgment of the gas production capacity of each layer has important significance for the drainage and production of the coal bed gas well and the implementation of yield increasing measures in the later period: first, the difference in productivity between layers is significant, 3^#Strong gas production capability of coal seam, 15^#Weak coal seam capacity and 3^#Weak gas production capacity of coal seam 15^#When the coal seam capacity is strong, different drainage and mining control methods are adopted to inhibit interlayer interference and fully release the single well productivity, so that 3 needs to be known in advance before gas production^#Coal seam and 15^#The productivity of the coal bed is high. For example, 1/3 of bottom hole flow pressure when the coal bed gas well sees gas is generally taken as the steady production pressure at present, and since two layers share one well bore water drainage gas production, 3^#Coal bed pressure is reduced first, 15^#The pressure of the coal bed is reduced later, so that the later period is mainly reduced by 15^#Coal bed pressure, release 15^#The coal bed productivity realizes stable production, if 15^#The gas production capability of the coal seam is poor, and in order to realize long-term stable production, the bottom hole flowing pressure during the stable production is higher than 1/3 of the bottom hole flowing pressure during the visible gas, if 15^#The gas production capacity of the coal seam is better, the bottom hole flowing pressure for starting stable production can be properly reduced, the single well productivity is fully released, and long-term high and stable production is realized. And secondly, after judging the gas production capacity of each layer, a new yield increase measure can be adopted for the layer with poor gas production capacity, so that the yield is increased.

At present, three methods are mainly used for predicting the layered gas production capacity of a commingled production well: first, production observation, when the working fluid level drops to 3^#After the coal bed is below the coal bed, the yield and casing pressure of the coal bed gas well are increased slowly or are not increased any more in the process of reducing the bottom hole flowing pressure, and the meterMing 15^#The gas production capability of coal is poor; after casing pressure of the coal-bed gas well is met, the yield and casing pressure of the coal-bed gas well are accelerated slowly or not in the process of bottom hole flowing pressure reduction, and the indication is 3^#The gas production capability of coal is poor. Secondly, a similar comparison method is carried out according to the stable gas production of the double-layer combined production well and the stable gas production of the adjacent single-layer development well, if the stable gas production of the double-layer combined production well is 3000 square/day, the adjacent single production well is 3^#If the stable gas production rate of the coal well is 2000 square/day, the stable gas production rate of the double-layer combined production well can be estimated to be about 1000 square/day. Thirdly, the development effect of each layer is presumed through reservoir parameters of each layer, such as structure, gas content, permeability, coal structure, fracturing effect and the like. For example, Song rock and the like propose 3 formation modes of the medium and high-rank coal bed gas enrichment high-yield region in a geological evaluation method and a formation mode of the medium and high-rank coal bed gas enrichment high-yield region published in the journal of the geological front, and the productivity of the reservoir can be judged according to the modes.

However, both the production observation method and the analog method can determine the layered gas production capacity after gas production even after stable gas production, and the coal bed gas well discharge and production control after gas production enters the middle and later stages, so that the coal bed gas well discharge and production management cannot be effectively guided. And the gas production capacity is predicted by geological parameters, so that the required geological parameters are more, each well is subjected to geological parameter testing, the consumed time is long, the cost is high, and the method is not suitable for large-scale field application. At present, most of the three methods are indirectly guessed by experience, and the coal bed gas reservoir plane heterogeneity is strong, and the difference among wells is large, so that the three methods are relatively poor in accuracy and reliability and cannot meet the drainage and production control requirements of a one-well one-method.

Disclosure of Invention

The embodiment of the application provides a method and a device for predicting the layered gas production capacity of a coalbed methane combined production well, which are simple to operate, accurate in prediction and suitable for field application. The technical scheme is as follows:

on the one hand, the method for predicting the layered gas production capacity of the coalbed methane combined production well comprises the following steps:

when the casing gas production gate is in a closed state, acquiring casing pressure data of the coal bed gas well and 15 after casing pressure is obtained^#Fluid pressure of coal seam floorForce;

determining the 15 based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the bottom surface of the coal bed;

by 3^#Coal seam and 15^#The vertical distance between coal layers is the critical point of the vertical height of the liquid column, and 3 are respectively obtained based on the casing pressure data and the vertical height of the liquid column^#First conversion information of the coal seam and 15^#Second conversion information of the coal seam, wherein the first conversion information and the second conversion information are respectively used for representing 3^#Coal seam and 15^#The conversion relation between the casing pressure data of the coal seam and the vertical height of the liquid column;

comparing the first conversion information with the second conversion information, and predicting theresult 3 according to the comparison result^#A coal seam and said 15^#Gas production capacity of the coal seam.

In one possible implementation mode, the casing pressure data of the coal-bed gas well and the casing pressure 15 obtained after casing pressure are acquired when the casing gas production gate is in a closed state^#Prior to the fluid pressure at the coal seam floor, the method further comprises:

after the coal bed gas well is put into operation, the sleeve gas production gate is kept in a closed state and passes through 15^#The electronic pressure gauge is put into the bottom of the coal seam for monitoring to record 15^#The fluid pressure at the bottom of the coal seam is monitored by installing a casing pressure gauge on the casing gas production pipeline to record casing pressure data until the liquid column in the shaft is reduced to 3^#A preset position below the coal seam.

In one possible implementation, thenumber 3^#Coal seam and 15^#The vertical distance between coal layers is the critical point of the vertical height of the liquid column, and 3 are respectively obtained based on the casing pressure data and the vertical height of the liquid column^#First conversion information of the coal seam and 15^#The second conversion information of the coal seam comprises:

acquiring a plurality of coordinate points by taking the casing pressure data as a vertical coordinate and taking the vertical height of the liquid column as a horizontal coordinate;

by 3^#Coal seam and 15^#The vertical distance between coal layers is the critical point of the vertical height of the liquid column, for the liquid columnCarrying out segmentation fitting on the coordinate point with the vertical height being greater than or equal to the vertical distance and the coordinate point with the vertical height being smaller than the vertical distance of the liquid column to obtain a first line segment and a second line segment, wherein the first line segment corresponds to 3^#A coal seam, the second line section corresponding to 15^#A coal seam;

obtaining the slope information of the first line segment as 3^#First conversion information of the coal seam;

obtaining the slope information of the second line segment as 15^#Second transformed information of the coal seam.

In one possible implementation, the determination 15 is based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the coal seam bottom surface comprises:

calculation 15 using the following equation^#Vertical height H of liquid column above coal bed bottom_wi：

H_wi＝(p_wf-p_t)/(ρg)*10⁶

In the formula, H_wiIn a well bore 15^#The vertical height of the liquid column above the bottom surface of the coal bed is m; p is a radical of_wfIs 15 of^#The fluid pressure at the bottom of the coal bed is in MPa; p is a radical of_tIs the sleeve pressure data with the unit of MPa; rho is the density of the liquid in the well bore and has the unit of kg/m³(ii) a g is the acceleration of gravity.

In a possible implementation manner, the comparison is performed based on the first conversion information and the second conversion information, and the 3 is predicted according to a comparison result^#A coal seam and said 15^#The gas production capacity of the coal seam comprises:

comparing the absolute value of the first conversion information with the absolute value of the second conversion information;

if the comparison result is that the absolute value of the first conversion information is smaller than the absolute value of the second conversion information, 3^#The gas production capability of the coal seam is inferior to 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is larger than the absolute value of the second conversion information, 3^#The gas production capacity of the coal bed is better than 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is equal to the absolute value of the second conversion information, 3^#Gas production capacity of coal seam and 15^#The gas production capacity of the coal seam is equivalent.

In one aspect, a device for predicting the layered gas production capacity of a coalbed methane combined production well is provided, which comprises:

the data acquisition module is used for acquiring casing pressure data of the coal-bed gas well and 15 after casing pressure is seen when the casing gas production gate is in a closed state^#Fluid pressure at the bottom of the coal seam;

a height determination module to determine the 15 based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the bottom surface of the coal bed;

a conversion information acquisition module for acquiring the conversion information as 3^#Coal seam and 15^#The vertical distance between coal layers is the critical point of the vertical height of the liquid column, and 3 are respectively obtained based on the casing pressure data and the vertical height of the liquid column^#First conversion information of the coal seam and 15^#Second conversion information of the coal seam, wherein the first conversion information and the second conversion information are respectively used for representing 3^#Coal seam and 15^#The conversion relation between the casing pressure data of the coal seam and the vertical height of the liquid column;

a prediction module for comparing the first conversion information with the second conversion information and predicting the 3^#A coal seam and said 15^#Gas production capacity of the coal seam.

In one possible implementation manner, the data acquisition module is further used for keeping the casing gas production gate in a closed state after the coal-bed gas well is put into operation, and 15 is used for controlling the casing gas production gate to be in a closed state^#The electronic pressure gauge is put into the bottom of the coal seam for monitoring to record 15^#The fluid pressure at the bottom of the coal seam is monitored by installing a casing pressure gauge on the casing gas production pipeline to record casing pressure data until the liquid column in the shaft is reduced to 3^#A preset position below the coal seam.

In a possible implementation manner, the conversion information obtaining module is configured to use the casing pressure data as a vertical coordinate and use a vertical height of the liquid column as a vertical heightAcquiring a plurality of coordinate points for the abscissa; by 3^#Coal seam and 15^#The vertical distance between coal layers is a critical point of the vertical height of a liquid column, and a first line segment and a second line segment are obtained by performing segmentation fitting on a coordinate point of which the vertical height of the liquid column is greater than or equal to the vertical distance and a coordinate point of which the vertical height of the liquid column is less than the vertical distance, wherein the first line segment corresponds to 3^#A coal seam, the second line section corresponding to 15^#A coal seam; obtaining the slope information of the first line segment as 3^#First conversion information of the coal seam; obtaining the slope information of the second line segment as 15^#Second transformed information of the coal seam.

In one possible implementation, the height determination module is configured to calculate 15 using the following equation^#Vertical height H of liquid column above coal bed bottom_wi：

H_wi＝(p_wf-p_t)/(ρg)*10⁶

In the formula, H_wiIn a well bore 15^#The vertical height of the liquid column above the bottom surface of the coal bed is m; p is a radical of_wfIs 15 of^#The fluid pressure at the bottom of the coal bed is in MPa; p is a radical of_tIs the sleeve pressure data with the unit of MPa; rho is the density of the liquid in the well bore and has the unit of kg/m³(ii) a g is the acceleration of gravity.

In one possible implementation, the prediction module is configured to:

comparing the absolute value of the first conversion information with the absolute value of the second conversion information;

if the comparison result is that the absolute value of the first conversion information is smaller than the absolute value of the second conversion information, 3^#The gas production capability of the coal seam is inferior to 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is larger than the absolute value of the second conversion information, 3^#The gas production capacity of the coal bed is better than 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is equal to the absolute value of the second conversion information, 3^#Gas production capacity of coal seam and 15^#The gas production capacity of the coal seam is equivalent.

According to the technical scheme, the gas production capacity of each layer can be judged before gas production of the coal-bed gas well based on the actual production parameters of each well, so that a basis is provided for formulation of row production degrees of stable gas production rate, stable production pressure and the like of the coal-bed gas well, and the gas production capacity is judged according to the actual production parameters of each well, so that adverse effects of coal-bed plane heterogeneity on a prediction result can be effectively avoided, the prediction accuracy is greatly improved, the prediction process does not need a large amount of geological parameters and high-depth geological knowledge, the operation is simple and convenient, the method is simple, the requirement on the user capacity is low, the method is suitable for large-scale field popularization, and the method can be popularized and applied to all coal-bed gas wells which are co-mined at more than two layers.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a flowchart of a method for predicting a stratified gas production capacity of a coalbed methane co-production well according to an embodiment of the present application;

fig. 2 is a flowchart of a method for predicting the stratified gas production capacity of a coalbed methane co-production well according to an embodiment of the present application;

FIG. 3 shows the X1 well in h₁₅A sectional fitting graph of the vertical height of the liquid column and the casing pressure is taken as a boundary point;

FIG. 4 shows the X2 well in h₁₅A sectional fitting graph of the vertical height of the liquid column and the casing pressure is taken as a boundary point;

fig. 5 is a schematic structural diagram of a device for predicting the layered gas production capacity of a coalbed methane co-production well according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of a computer device according to an embodiment of the present application.

Detailed Description

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

Fig. 1 is a flowchart of a method for predicting a stratified gas production capacity of a coalbed methane co-production well according to an embodiment of the present application. Referring to fig. 1, the embodiment may include:

101. when the casing gas production gate is in a closed state, acquiring casing pressure data of the coal bed gas well and 15 after casing pressure is obtained^#Fluid pressure at the bottom surface of the coal seam.

102. Determining the 15 based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the coal seam floor.

103. By 3^#Coal seam and 15^#The vertical distance between coal layers is the critical point of the vertical height of the liquid column, and 3 are respectively obtained based on the casing pressure data and the vertical height of the liquid column^#First conversion information of the coal seam and 15^#Second conversion information of the coal seam, wherein the first conversion information and the second conversion information are respectively used for representing 3^#Coal seam and 15^#And (3) conversion relation between casing pressure data of the coal seam and the vertical height of the liquid column.

104. Comparing the first conversion information with the second conversion information, and predicting theresult 3 according to the comparison result^#A coal seam and said 15^#Gas production capacity of the coal seam.

In one possible implementation mode, the casing pressure data of the coal-bed gas well and the casing pressure 15 obtained after casing pressure are acquired when the casing gas production gate is in a closed state^#Prior to the fluid pressure at the coal seam floor, the method further comprises:

after the coal bed gas well is put into operation, the sleeve gas production gate is kept in a closed state and passes through 15^#The electronic pressure gauge is put into the bottom of the coal seam for monitoring to record 15^#The fluid pressure at the bottom of the coal seam is monitored by installing a casing pressure gauge on the casing gas production pipeline to record casing pressure data until the liquid column in the shaft is reduced to 3^#A preset position below the coal seam.

In one possible implementation, thenumber 3^#Coal seam and 15^#Sag between coal seamsThe straight distance is a critical point of the vertical height of the liquid column, and 3 are respectively obtained based on the casing pressure data and the vertical height of the liquid column^#First conversion information of the coal seam and 15^#The second conversion information of the coal seam comprises:

acquiring a plurality of coordinate points by taking the casing pressure data as a vertical coordinate and taking the vertical height of the liquid column as a horizontal coordinate;

by 3^#Coal seam and 15^#The vertical distance between coal layers is a critical point of the vertical height of a liquid column, and a first line segment and a second line segment are obtained by performing segmentation fitting on a coordinate point of which the vertical height of the liquid column is greater than or equal to the vertical distance and a coordinate point of which the vertical height of the liquid column is less than the vertical distance, wherein the first line segment corresponds to 3^#A coal seam, the second line section corresponding to 15^#A coal seam;

obtaining the slope information of the first line segment as 3^#First conversion information of the coal seam;

obtaining the slope information of the second line segment as 15^#Second transformed information of the coal seam.

In one possible implementation, the determination 15 is based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the coal seam bottom surface comprises:

calculation 15 using the following equation^#Vertical height H of liquid column above coal seam bottom surface_wi：

H_wi＝(p_wf-p_t)/(ρg)*10⁶

In the formula, H_wiIn a well bore 15^#The vertical height of the liquid column above the bottom surface of the coal bed is m; p is a radical of_wfIs 15 of^#The fluid pressure at the bottom of the coal bed is in MPa; p is a radical of_tIs the sleeve pressure data with the unit of MPa; rho is the density of the liquid in the well bore and has the unit of kg/m³(ii) a g is the acceleration of gravity.

In a possible implementation manner, the comparison is performed based on the first conversion information and the second conversion information, and the 3 is predicted according to a comparison result^#A coal seam and said 15^#The gas production capacity of the coal seam comprises:

comparing the absolute value of the first conversion information with the absolute value of the second conversion information;

if the comparison result is that the absolute value of the first conversion information is smaller than the absolute value of the second conversion information, 3^#The gas production capability of the coal seam is inferior to 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is larger than the absolute value of the second conversion information, 3^#The gas production capacity of the coal bed is better than 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is equal to the absolute value of the second conversion information, 3^#Gas production capacity of coal seam and 15^#The gas production capacity of the coal seam is equivalent.

All the above optional technical solutions may be combined arbitrarily to form the optional embodiments of the present disclosure, and are not described herein again.

According to the technical scheme, the gas production capacity of each layer can be judged before gas production of the coal-bed gas well based on the actual production parameters of each well, so that a basis is provided for formulation of row production degrees of stable gas production rate, stable production pressure and the like of the coal-bed gas well, and the gas production capacity is judged according to the actual production parameters of each well, so that adverse effects of coal-bed plane heterogeneity on a prediction result can be effectively avoided, the prediction accuracy is greatly improved, the prediction process does not need a large amount of geological parameters and high-depth geological knowledge, the operation is simple and convenient, the method is simple, the requirement on the user capacity is low, the method is suitable for large-scale field popularization, and the method can be popularized and applied to all coal-bed gas wells which are co-mined at more than two layers.

Fig. 2 is a flowchart of a method for predicting a stratified gas production capacity of a coalbed methane co-production well according to an embodiment of the present application. Referring to fig. 2, the embodiment may include:

201. after the coal bed gas well is put into operation, the sleeve gas production gate is kept in a closed state and passes through 15^#The electronic pressure gauge is put into the bottom of the coal seam for monitoring to record 15^#The fluid pressure at the bottom of the coal seam is monitored by installing a casing pressure gauge on the casing gas production pipeline so as to record casing pressure data until the shaftThe liquid column in (1) is lowered to 3^#A preset position below the coal seam.

The data obtained through detection can be stored in a time sequence based on the acquisition time, so that the continuous recording of the fluid pressure and the casing pressure data is realized.

Wherein the preset position may refer to 3^#Below the coal seam, and 3^#The vertical distance between the coal seams is about 10m or more, and of course, different preset positions may be set according to different coal seams, which is not specifically limited in the embodiment of the present application.

202. Acquiring casing pressure data and 15 of the coal-bed gas well after casing pressure is seen from the recorded data^#Fluid pressure at the bottom surface of the coal seam.

It should be noted that the fluid pressure at the bottom of the coal seam may also be referred to as the bottom hole flowing pressure of the coal seam. In addition, the casing pressure data referred to in the embodiments of the present application may be casing pressure data at multiple times, so as to describe the casing pressure variation of the coal-bed gas well in more detail.

By detecting the recorded data, the data of the stage of starting to discharge and acquire the casing pressure can be determined, the data are excluded, and only the fluid pressure and the casing pressure data after the casing pressure is seen are referred, so that the condition of inaccurate prediction caused by data interference can be avoided.

203. Based on the fluid pressure and casing pressure data obtained instep 202, a determination 15 is made^#The vertical height of the liquid column above the coal seam floor.

Calculation 15 using the following equation^#Vertical height H of liquid column above coal seam bottom surface_wi：

H_wi＝(p_wf-p_t)/(ρg)*10⁶ (1)

In the formula (1), H_wiIn a well bore 15^#The vertical height of the liquid column above the bottom surface of the coal bed is m; p is a radical of_wfIs 15 of^#The fluid pressure at the bottom of the coal bed is in MPa; p is a radical of_tIs casing pressure data, namely gas pressure in a shaft, and the unit is MPa; rho is the density of the liquid in the well bore and has the unit of kg/m³(ii) a g is the acceleration of gravity. Wherein, the value in the rho engineering can be the density of waterDegree 10³kg/m³(ii) a The value in the engineering of g may be 10N/kg.

204. And taking the sleeve pressure data as a vertical coordinate and the vertical height of the liquid column as an abscissa to obtain a plurality of coordinate points.

In this step, in a rectangular coordinate system, a coordinate group (H) is formed with the liquid column vertical height as the abscissa and the jacket pressure data as the ordinate_wi，p_ti). E.g. vertical height H of the liquid column_w1Corresponding sleeve pressure p_t1The coordinate point is (H)_w1，p_t1) (ii) a Vertical height H of liquid column_w2Corresponding sleeve pressure p_t2The coordinate point is (H)_w2，p_t2) (ii) a Coordinate point (H)_w1，p_t1)，(H_w2，p_t2)，……(H_wi，p_ti) And drawing in a rectangular coordinate system. Of course, when the computer device performs the prediction, a visual view may be provided to display the plurality of coordinate points, and only a visual graph of the subsequently generated conversion information may be displayed.

205. By 3^#Coal seam and 15^#The vertical distance between coal layers is a critical point of the vertical height of a liquid column, and a first line segment and a second line segment are obtained by performing segmentation fitting on a coordinate point of which the vertical height of the liquid column is greater than or equal to the vertical distance and a coordinate point of which the vertical height of the liquid column is less than the vertical distance, wherein the first line segment corresponds to 3^#A coal seam, the second line section corresponding to 15^#A coal seam.

Therein, 3^#Coal seam and 15^#The vertical distance between coal seams can be obtained by the following process: determining 3 from well log data^#Coal seam and 15^#Coal seam vertical depth, calculate 3^#Coal seam and 15^#The vertical depth of the coal seam, the vertical distance between coal seams is determined, and is herein designated as h₁₅. When the vertical height H of the liquid column_wi＝h₁₅When the working fluid level in the shaft is 3^#Near the coal seam; when the vertical height H of the liquid column_wi<h₁₅While the working fluid level in the shaft is reduced to 3^#Below the coal seam, when the vertical height H of the liquid column_wi>h₁₅When the working fluid level in the shaft is 3^#Above the coal seam.

Further, in a rectangular coordinate system, with H_wi＝h₁₅Is the critical point, pair (H)_wi，p_ti) The coordinate set is subjected to piecewise linear fitting to obtain a coordinate H_wi<h₁₅The fitted line segment of time, i.e. the second line segment, and H_wi>h₁₅The fitting line segment of time is also the first line segment.

206. Obtaining the slope information of the first line segment as 3^#Obtaining the slope information of the second line segment as the first conversion information of the coal seam, wherein the slope information of the second line segment is 15^#Second transformed information of the coal seam.

Acquiring the slope information of the first line segment and the second line segment based on the fitted first line segment and second line segment, and respectively taking the slope information as 3^#First conversion information of the coal seam and 15^#For convenience of representation, the second conversion information of the coal seam may be denoted as k_3，The second conversion information is denoted by k₁₅。

The slope of the line segment may represent the casing pressure conversion rate of the coal seam. The coal-bed methane well is drained continuously, the bottom hole flow pressure is reduced to be lower than desorption pressure, and the coal-bed methane begins to desorb and is gathered in a shaft to form casing pressure; along with the continuous descending of the liquid column in the shaft, the casing pressure continuously rises until the liquid column in the shaft is completely converted into the casing pressure; the gas production capacities of coal bed gas wells are different, and the casing pressure increase amplitude caused by the unit height of the liquid column drop, namely the casing pressure conversion rate of the unit liquid column is different, so that the conversion condition from the liquid column generating pressure to the casing pressure of each coal bed in a shaft, namely the conversion information capable of expressing the casing pressure conversion rate can be adopted as the evaluation index of the gas production capacity of each layer, and the higher the casing pressure conversion rate of the liquid column is, the higher the gas production capacity is.

Accordingly, in the present embodiment, at 15^#Before coal bed desorption, the casing pressure conversion rate of unit liquid column descending amplitude in a shaft can be effectively represented by 3^#Gas production capacity of coal; when the working fluid level is reduced to 3^#Coal and below, 3^#Gas production capacity of coalAfter full release and gradual entering into failure period, further reducing the height of the liquid column in the shaft, 3^#The gas production capacity of the coal cannot be increased, and the casing pressure conversion rate of a liquid column in the shaft is reflected by 15^#The gas production capacity of the coal is high and low. Thus, at a vertical distance H_wi＝h₁₅Performing piecewise fitting for the critical point, and obtaining the absolute value of two slopes as 3^#Coal and 15^#The casing pressure conversion rate of the liquid column of coal can be respectively represented by 3^#Coal and 15^#The gas production capacity of the coal is high and low.

207. Comparing the absolute value of the first conversion information with the absolute value of the second conversion information, and if the absolute value of the first conversion information is smaller than the absolute value of the second conversion information, then 3^#The gas production capability of the coal seam is inferior to 15^#A coal seam; if the comparison result is that the absolute value of the first conversion information is larger than the absolute value of the second conversion information, 3^#The gas production capacity of the coal bed is better than 15^#A coal seam; if the comparison result is that the absolute value of the first conversion information is equal to the absolute value of the second conversion information, 3^#Gas production capacity of coal seam and 15^#The gas production capacity of the coal seam is equivalent.

Based on the above example, if | k₁₅|<|k₃I, then 15^#Gas production capacity ratio ofcoal 3^#Coal difference; if | k₁₅|>|k₃I, then 15^#Gas production capacity ratio ofcoal 3^#The coal is good; if | k₁₅|＝|k₃I, then 15^#Coal and 3^#The gas production capacity of the coal is equivalent.

Of course, there may also be some redundant control over the above-mentioned comparison, that is, when the absolute value of the difference between the first conversion information and the second conversion information is smaller than the target value, for example, 0.0005, it may also be considered that the absolute value of the first conversion information is equal to the absolute value of the second conversion information, and then 15^#Gas production capacity of coal seam and 3^#The gas production capacity of the coal seam is equivalent. And when the comparison result is that the absolute value of the first conversion information is smaller than that of the second conversion information and the absolute value of the difference is larger than the target value, 3^#The gas production capability of the coal seam is inferior to 15^#A coal seam; if the comparison result is that the absolute value of the first conversion information is larger than that of the second conversion information and the absolute value of the difference value is larger than the target value, 3^#The gas production capacity of the coal bed is better than 15^#And (4) the coal bed to eliminate calculation errors caused by some data errors.

According to the technical scheme, the gas production capacity of each layer can be judged before gas production of the coal-bed gas well based on the actual production parameters of each well, so that a basis is provided for formulation of row production degrees of stable gas production rate, stable production pressure and the like of the coal-bed gas well, and the gas production capacity is judged according to the actual production parameters of each well, so that adverse effects of coal-bed plane heterogeneity on a prediction result can be effectively avoided, the prediction accuracy is greatly improved, the prediction process does not need a large amount of geological parameters and high-depth geological knowledge, the operation is simple and convenient, the method is simple, the requirement on the user capacity is low, the method is suitable for large-scale field popularization, and the method can be popularized and applied to all coal-bed gas wells which are co-mined at more than two layers.

In the following, taking the X1 well as an example, the well is 3^#Coal, 15^#In order to predict the layered gas production capacity of the coal co-production well, according to the steps shown in the figure 2, the following prediction can be carried out:

the method comprises the following steps: before X1 well production, at 15^#And (4) putting an electronic pressure gauge at the bottom of the coal seam, and installing a sleeve pressure gauge on a wellhead gas production pipeline. The X1 well is put into production in 2017, 7 and 20 days, the casing gas production gate is kept in a closed state after the production, and the 15 detected by the device are continuously and remotely transmitted and recorded by an automatic system^#Fluid pressure and casing pressure data at the bottom of the coal seam until the fluid column in the wellbore drops to 3^#26m below the coal seam.

Step two: extracting 15% of the casing pressure of the coal-bed gas well from the data^#The fluid pressure and casing pressure data at the bottom of the coal seam are calculated by using the formula (1) 15^#The results are shown in table 1, above the coal seam floor, at the vertical height of the fluid column.

TABLE 1

Step three: in the rectangular coordinate system, a coordinate group (280, 0.002), (278.4, 0.017), (276.3, 0.037), … … (95.7, 1.547) is plotted in the rectangular coordinate system with the vertical height of the liquid column as the abscissa and the sleeve pressure data as the ordinate, as shown in fig. 3.

Step four: determining 3 from well log data^#The vertical depth (i.e. vertical depth) of the coal seam is 780.5m and 15^#The vertical depth of the coal seam is 892.9m and 3^#Coal seam and 15^#The vertical distance between coal beds is H_wi＝h₁₅＝112.4。

Step five: in the rectangular coordinate system drawn in the third step, H is used_wi＝h₁₅112.4 is a critical point, and piecewise linear fitting is carried out on the data to obtain the current H_wi<Slope of fitted segment at 112.4 is k₁₅＝-0.0016，H_wi>Slope of fitted segment at 112.4 is k₃＝-0.0097。

Step six: the comparison result is | k₁₅|＝0.0016<|k₃0.0097, then 15^#Gas production capacity ratio ofcoal 3^#Coal difference, the well dynamic liquid level drops to 15^#After the coal is below, the bottom hole flowing pressure is reduced, and the yield and the casing pressure are not increased, which shows that 15^#The coal yield is extremely low, and the data can show that the prediction method can effectively predict the single-layer gas production capacity.

Taking the X2 well as an example, the well is 3^#Coal, 15^#In order to predict the layered gas production capacity of the coal co-production well, according to the steps shown in the figure 2, the following prediction can be carried out:

the method comprises the following steps: before X2 well production, at 15^#Coal seam bottom run-inThe electronic pressure gauge is arranged on a wellhead gas production pipeline. The X2 well is put into production in 2017, 8 and 15 days, the casing gas production gate is kept in a closed state after the production, and the 15 detected by the device are continuously and remotely transmitted and recorded by an automatic system^#Fluid pressure and casing pressure data at the bottom of the coal seam until the fluid column in the wellbore drops to 3^#45.6m below the coal seam.

Step two: extracting 15% of the casing pressure of the coal-bed gas well from the data^#The fluid pressure and casing pressure data at the bottom of the coal seam are calculated by using the formula (1) 15^#The results are shown in table 2, above the coal seam floor, at the vertical height of the fluid column.

TABLE 2

Step three: in the rectangular coordinate system, with the vertical height of the liquid column as the abscissa and the jacket pressure as the ordinate, the coordinate groups (363.5, 0.002), (361.5, 0.02), (358.9, 0.043), … … (48.8, 3.037) are plotted in the rectangular coordinate system, as shown in fig. 4.

Step four: determining 3 from well log data^#The vertical depth of the coal seam is 745.7m and 15^#The vertical depth of the coal bed is 840.1m and 3^#Coal seam and 15^#The vertical distance between coal beds is H_wi＝h₁₅＝94.4m。

Step five: in the rectangular coordinate system drawn in the third step, H is used_wi＝h₁₅Taking 94.4 as a critical point, and performing piecewise linear fitting on the data to obtain a curve H_wi<The slope of the fitting segment at 94.4 is k₁₅＝-0.0096，H_wi>The slope of the fitting segment at 94.4 is k₃＝-0.0097。

Step six: the comparison result is | k₁₅-k₃|＝0.0001<0.0005, then X2 well 3^#Coal and 15^#The gas production capacity of the coal is equivalent. The well practiceStable gas production 3000 square, and the working fluid level is reduced to 15^#After the coal is below, as the bottom hole flow pressure decreases, both production and casing pressure increase, indicating 15^#The coal yield capacity is stronger. The data show that the prediction method can effectively predict the single-layer gas production capacity.

Fig. 5 is a schematic structural diagram of a device for predicting the layered gas production capability of a coalbed methane co-production well according to an embodiment of the present application, and referring to fig. 5, the device includes:

adata obtaining module 501, configured to obtain casing pressure data of the coal-bed gas well and 15 after casing pressure is found when the casing gas production gate is in a closed state^#Fluid pressure at the bottom of the coal seam;

aheight determination module 502 to determine the 15 based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the bottom surface of the coal bed;

a conversioninformation obtaining module 503 for obtaining the conversion information by 3^#Coal seam and 15^#The vertical distance between coal layers is the critical point of the vertical height of the liquid column, and 3 are respectively obtained based on the casing pressure data and the vertical height of the liquid column^#First conversion information of the coal seam and 15^#Second conversion information of the coal seam, wherein the first conversion information and the second conversion information are respectively used for representing 3^#Coal seam and 15^#The conversion relation between the casing pressure data of the coal seam and the vertical height of the liquid column;

aprediction module 504, configured to compare the first conversion information with the second conversion information, and predict the 3 th conversion according to a comparison result^#A coal seam and said 15^#Gas production capacity of the coal seam.

In a possible implementation manner, the data acquisition module is further configured to

After the coal bed gas well is put into operation, the sleeve gas production gate is kept in a closed state and passes through 15^#The electronic pressure gauge is put into the bottom of the coal seam for monitoring to record 15^#The fluid pressure at the bottom of the coal seam is monitored by installing a casing pressure gauge on the casing gas production pipeline to record casing pressure data until the liquid column in the shaft is reduced to 3^#A preset position below the coal seam.

In a possible implementation manner, the conversion information obtaining module is configured to obtain a plurality of coordinate points by using the casing pressure data as a vertical coordinate and using a vertical height of the liquid column as a horizontal coordinate; by 3^#Coal seam and 15^#The vertical distance between coal layers is a critical point of the vertical height of a liquid column, and a first line segment and a second line segment are obtained by performing segmentation fitting on a coordinate point of which the vertical height of the liquid column is greater than or equal to the vertical distance and a coordinate point of which the vertical height of the liquid column is less than the vertical distance, wherein the first line segment corresponds to 3^#A coal seam, the second line section corresponding to 15^#A coal seam; obtaining the slope information of the first line segment as 3^#First conversion information of the coal seam; obtaining the slope information of the second line segment as 15^#Second transformed information of the coal seam.

In one possible implementation, the height determination module is configured to calculate 15 using the following equation^#Vertical height H of liquid column above coal bed bottom_wi：

H_wi＝(p_wf-p_t)/(ρg)*10⁶

In the formula, H_wiIn a well bore 15^#The vertical height of the liquid column above the bottom surface of the coal bed is m; p is a radical of_wfIs 15 of^#The fluid pressure at the bottom of the coal bed is in MPa; p is a radical of_tIs the sleeve pressure data with the unit of MPa; rho is the density of the liquid in the well bore and has the unit of kg/m³(ii) a g is the acceleration of gravity.

In one possible implementation, the prediction module is configured to:

comparing the absolute value of the first conversion information with the absolute value of the second conversion information;

if the comparison result is that the absolute value of the first conversion information is smaller than the absolute value of the second conversion information, 3^#The gas production capability of the coal seam is inferior to 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is larger than the absolute value of the second conversion information, 3^#The gas production capacity of the coal bed is better than 15^#A coal seam;

if it is saidIf the absolute value of the first conversion information is equal to the absolute value of the second conversion information, then 3^#Gas production capacity of coal seam and 15^#The gas production capacity of the coal seam is equivalent.

All the above optional technical solutions may be combined arbitrarily to form the optional embodiments of the present disclosure, and are not described herein again.

It should be noted that: the device for predicting the layered gas production capacity of the coalbed methane co-production well is exemplified by the division of the functional modules when the interactive prop is controlled, and in practical application, the function distribution can be completed by different functional modules according to needs, that is, the internal structure of the terminal is divided into different functional modules so as to complete all or part of the functions described above. In addition, the device for predicting the layered gas production capability of the coalbed methane combined production well and the method for predicting the layered gas production capability of the coalbed methane combined production well provided by the embodiments belong to the same concept, and the specific implementation process is detailed in the method for predicting the layered gas production capability of the coalbed methane combined production well, and is not described herein again.

In an exemplary embodiment, a computer readable storage medium, such as a memory, including at least one program code, the at least one program code being executable by a processor in a terminal to perform the method for predicting the stratified gas production capacity of a coalbed methane co-production well in the above embodiments is also provided. For example, the computer-readable storage medium may be a ROM (Read-Only Memory), a RAM (Random-Access Memory), a CD-ROM (Compact Disc Read-Only Memory), a magnetic tape, a floppy disk, an optical data storage device, and the like.

Fig. 6 is a schematic structural diagram of acomputer device 600 according to an embodiment of the present application, where thecomputer device 600 may generate a relatively large difference due to different configurations or performances, and may include one or more processors (CPUs) 601 and one or more memories 602, where the memory 602 stores at least one instruction, and the at least one instruction is loaded and executed by the processor 601 to implement the methods provided by the method embodiments. Certainly, the computer device may further have components such as a wired or wireless network interface, a keyboard, and an input/output interface, so as to perform input and output, and the computer device may further include other components for implementing the functions of the device, which is not described herein again.

It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (8)

1. A method for predicting the layered gas production capacity of a coalbed methane combined production well is characterized by comprising the following steps:

when the casing gas production gate is in a closed state, acquiring casing pressure data of the coal bed gas well and 15 after casing pressure is obtained^#Fluid pressure at the bottom of the coal seam;

determining the 15 based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the bottom surface of the coal bed;

acquiring a plurality of coordinate points by taking the casing pressure data as a vertical coordinate and taking the vertical height of the liquid column as a horizontal coordinate;

by 3^#Coal seam and 15^#The vertical distance between coal layers is a critical point of the vertical height of a liquid column, and a first line segment and a second line segment are obtained by performing segmentation fitting on a coordinate point of which the vertical height of the liquid column is greater than or equal to the vertical distance and a coordinate point of which the vertical height of the liquid column is less than the vertical distance, wherein the first line segment corresponds to 3^#A coal seam, the second line section corresponding to 15^#A coal seam;

obtaining the slope information of the first line segment as 3^#First conversion information of the coal seam;

obtaining the slope information of the second line segment as 15^#Second conversion information of the coal seam;

comparing the first conversion information with the second conversion information, and predicting the result 3 according to the comparison result^#A coal seam and said 15^#Gas production capacity of the coal seam.

2. The method of claim 1, wherein the casing pressure data of the coal-bed gas well and the casing pressure 15 obtained after the casing pressure data are acquired when the casing gas production gate is in a closed state^#Prior to the fluid pressure at the coal seam floor, the method further comprises:

after the coal bed gas well is put into operation, the sleeve gas production gate is kept in a closed state and passes through 15^#The electronic pressure gauge is put into the bottom of the coal seam for monitoring to record 15^#The fluid pressure at the bottom of the coal seam is monitored by installing a casing pressure gauge on the casing gas production pipeline to record casing pressure data until the liquid column in the shaft is reduced to 3^#A preset position below the coal seam.

3. The method of claim 1, wherein the determining 15 is based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the coal seam bottom surface comprises:

calculation 15 using the following equation^#Vertical height H of liquid column above coal bed bottom_wi：

H_wi＝(p_wf-p_t)/(ρg)*10⁶

In the formula, H_wiIn a well bore 15^#The vertical height of the liquid column above the bottom surface of the coal bed is m; p is a radical of_wfIs 15 of^#The fluid pressure at the bottom of the coal bed is in MPa; p is a radical of_tIs the sleeve pressure data with the unit of MPa; rho is the density of the liquid in the well bore and has the unit of kg/m³(ii) a g is the acceleration of gravity.

4. The method of claim 1, wherein the comparison is based on the first transformation information and the second transformation information, according toComparing the results, predicting the 3^#A coal seam and said 15^#The gas production capacity of the coal seam comprises:

comparing the absolute value of the first conversion information with the absolute value of the second conversion information;

if the comparison result is that the absolute value of the first conversion information is smaller than the absolute value of the second conversion information, 3^#The gas production capability of the coal seam is inferior to 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is larger than the absolute value of the second conversion information, 3^#The gas production capacity of the coal bed is better than 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is equal to the absolute value of the second conversion information, 3^#Gas production capacity of coal seam and 15^#The gas production capacity of the coal seam is equivalent.

5. The utility model provides a coalbed methane commingled production well layering gas production ability prediction unit which characterized in that includes:

the data acquisition module is used for acquiring casing pressure data of the coal-bed gas well and 15 after casing pressure is seen when the casing gas production gate is in a closed state^#Fluid pressure at the bottom of the coal seam;

a height determination module to determine the 15 based on the fluid pressure and the casing pressure data^#The vertical height of the liquid column above the bottom surface of the coal bed;

the conversion information acquisition module is used for acquiring a plurality of coordinate points by taking the sleeve pressure data as a vertical coordinate and taking the vertical height of the liquid column as a horizontal coordinate; by 3^#Coal seam and 15^#The vertical distance between coal layers is a critical point of the vertical height of a liquid column, and a first line segment and a second line segment are obtained by performing segmentation fitting on a coordinate point of which the vertical height of the liquid column is greater than or equal to the vertical distance and a coordinate point of which the vertical height of the liquid column is less than the vertical distance, wherein the first line segment corresponds to 3^#A coal seam, the second line section corresponding to 15^#A coal seam; obtaining the slope information of the first line segment as 3^#First conversion information of the coal seam; skewing the second line segmentRate information is acquired as said 15^#Second conversion information of the coal seam;

a prediction module for comparing the first conversion information with the second conversion information and predicting the 3^#A coal seam and said 15^#Gas production capacity of the coal seam.

6. The apparatus of claim 5, wherein the data acquisition module is further configured to maintain the casing production gate closed after the coalbed methane well is delivered, via 15^#The electronic pressure gauge is put into the bottom of the coal seam for monitoring to record 15^#The fluid pressure at the bottom of the coal seam is monitored by installing a casing pressure gauge on the casing gas production pipeline to record casing pressure data until the liquid column in the shaft is reduced to 3^#A preset position below the coal seam.

7. The apparatus of claim 5, wherein the height determining module is configured to calculate 15 using the equation^#Vertical height H of liquid column above coal bed bottom_wi：

H_wi＝(p_wf-p_t)/(ρg)*10⁶

In the formula, H_wiIn a well bore 15^#The vertical height of the liquid column above the bottom surface of the coal bed is m; p is a radical of_wfIs 15 of^#The fluid pressure at the bottom of the coal bed is in MPa; p is a radical of_tIs the sleeve pressure data with the unit of MPa; rho is the density of the liquid in the well bore and has the unit of kg/m³(ii) a g is the acceleration of gravity.

8. The apparatus of claim 5, wherein the prediction module is configured to:

comparing the absolute value of the first conversion information with the absolute value of the second conversion information;

if the comparison result is that the absolute value of the first conversion information is smaller than the absolute value of the second conversion information, 3^#The gas production capability of the coal seam is inferior to 15^#A coal seam;

if the comparison is positiveIf the absolute value of the first conversion information is larger than the absolute value of the second conversion information, 3^#The gas production capacity of the coal bed is better than 15^#A coal seam;

if the comparison result is that the absolute value of the first conversion information is equal to the absolute value of the second conversion information, 3^#Gas production capacity of coal seam and 15^#The gas production capacity of the coal seam is equivalent.

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