CN112392448A - Multilayer dense sandstone gas reservoir perforation well section optimization method - Google Patents

Abstract

The invention belongs to the technical field of multilayer commingled production of compact gas reservoirs, and particularly relates to a multilayer system compact sandstone gas reservoir perforation well section optimization method. The method comprises the six steps of obtaining the static parameters of the gas well in the gas reservoir, converting the gas production contribution rate of each layer of the gas well in the gas reservoir into the weight coefficient, selecting the perforation layer position, determining the thickness of the perforation section, judging the specific depth of the perforation section and carrying out perforation, so that the most reasonable perforation section is efficiently and accurately selected, the selected perforation section is used for achieving the best transformation effect, and the method has stronger field applicability. The method can be combined with the real-time adjustment parameter formula of the production progress, repeatedly verifies the prediction result, and has strong timeliness. The method is simple to operate and low in cost, and the purposes of cost reduction and efficiency improvement are really achieved.

Description

Multilayer dense sandstone gas reservoir perforation well section optimization method

Technical Field

The invention belongs to the technical field of multilayer commingled production of compact gas reservoirs, and particularly relates to a multilayer system compact sandstone gas reservoir perforation well section optimization method.

Background

Low permeability tight sandstone gas reservoirs are widely distributed in multiple regions. However, as the production scale is continuously enlarged, the geological conditions of the reservoir between wells become more and more complex, interlayer interference exists between multiple layers of the reservoir in the vertical direction, and the exertion of the gas well yield is influenced by the heterogeneity of the plane and the difference of the vertical direction.

The perforation well section is an important factor influencing the development effect of a new well, and the reasonable selection of the perforation well section not only needs to improve the utilization degree of the residual reserves in the heterogeneous gas reservoir, but also meets the requirements of layer system development and related gas production process technologies. Therefore, the preferred research on the perforated well section of the multilayer series reservoir tends to be more refined, quantified, efficient and consistent with the actual production dynamics. Meanwhile, with the current great reduction of oil price and the continuous increase of environmental protection and borrowing cost, the development cost of multilayer perforation fracturing modification is invisibly increased, and the high-efficiency development of the gas field is severely restricted. In order to ensure that the yield of the gas well is reasonably exerted and the production cost is reduced and the efficiency is maximized, how to realize the selection of the optimal perforation well section to achieve the best exploitation effect is a key problem for improving the development benefit of the gas field.

Disclosure of Invention

The invention provides a multilayer tight sandstone gas reservoir perforation well section optimization method, and aims to provide a method for reducing the influence degree of interlayer interference on gas quantity, achieving the purpose of determining the position of a perforation section with high precision, high quality and high efficiency, providing a reliable basis for a perforation fracturing technology, and ensuring the high-efficiency and reasonable exertion of the yield of a new well.

A multilayer dense sandstone gas reservoir perforation well section optimization method,

the method comprises the following steps: acquiring static parameters of a gas well in a gas reservoir;

step two; converting each layer of gas production contribution rate of a gas well in a gas reservoir into a weight coefficient;

step three; establishing a single-layer comprehensive index by using the first step and the second step, and selecting a perforation layer by using the single-layer comprehensive index;

step four; determining the thickness of a perforation section according to the static parameters of the gas well obtained in the first step;

step five; judging the specific depth of the perforation well section according to the third step and the fourth step;

step six; and performing perforation according to the result obtained in the step five.

The static parameters of the gas well in the first step comprise effective thickness, porosity, permeability, gas saturation and sand body interpretation conclusion.

Converting the gas production contribution rate of the gas well in the gas reservoir into a weight coefficient by adopting a reference normalization method; the method comprises the following steps:

the first step is as follows: solving the drilling rate of each layer of the gas well;

the second step is that: taking the layer corresponding to the maximum drilling chance rate as a reference layer;

the third step: normalizing the gas production contribution rate of each layer of the gas well to a datum plane through the following formula:

each layer normalized value is the gas production contribution rate of each layer/the gas production contribution rate of the reference layer;

the fourth step: and respectively calculating the average value of the same-layer normalization values of all gas wells in the gas reservoir, wherein the calculated average value of the same-layer normalization values is the weight coefficient of each layer.

The first step of solving the drilling rate of each layer of the gas well is carried out by adopting the following formula

The drilling rate is the number of wells drilled to the layer/total number of wells in the gas reservoir.

The specific method for selecting the perforation horizon in the third step comprises the following steps:

the first step is as follows: establishing a single layer composite index

The single-layer comprehensive index K is equal to the weight coefficient of each layer multiplied by the sand body coefficient multiplied by the effective thickness multiplied by the permeability multiplied by the porosity multiplied by the gas saturation;

the second step is that: and sequencing the comprehensive indexes of the single layers from large to small, and selecting the layer with the comprehensive index of each single layer positioned at the first 3-5 positions as a perforation layer.

The sand body coefficient is the coefficient value corresponding to the interpretation conclusion of each sand body, namely, the gas layer, the gas-containing layer, the water-containing layer, the gas-containing water layer and the dry layer, wherein the coefficient value of the gas layer is 1, the coefficient value of the gas-containing layer is 0.8, the coefficient value of the water-containing layer is 0.5, the coefficient value of the gas-containing water layer is 0.2 and the coefficient value of the dry layer is 0.

The thickness of the perforation section determined in the fourth step is obtained by adopting the following formula

The perforation thickness is 0.31 x effective thickness + 1.08.

The method for judging the specific perforation position of the perforation well section in the fifth step comprises the following steps,

the first step is as follows: extracting a natural gamma GR curve corresponding to the gas layer section;

the second step is that: determining a perforation position according to the GR curve obtained in the step one and the deposition type;

the third step: and determining the specific perforation position, analyzing the GR curve distribution trend, calculating the GR average value of the gas interval, and judging the position as the specific perforation depth when the GR value of 3 meters is less than the GR average value by 50%.

The method for determining the perforation area by combining the deposition type in the second step comprises the following steps: when the GR curve is bell-shaped, the sedimentary microfacies are riverway sedimentary with positive rhythm, and the perforation section is selected at the middle lower part of the sand body; when the GR curve is funnel-shaped, the sedimentary microfacies are sedimentary by a estuary sand dam or a bank overflow sand dam with reverse rhythm, and the perforation section is selected at the middle upper part of the sand body; when the GR curve is box-shaped, the deposition microphase is the deposition of the cardiac beach dam with the homogeneity law, and the perforation section is selected in the middle of the sand body.

Has the advantages that:

(1) the invention can efficiently and accurately select the most reasonable perforation well section, achieves the best transformation effect by using the optimal perforation well section and has stronger field applicability.

(2) The method combines the real-time adjustment parameter formula of the production progress, repeatedly verifies the prediction result, and has strong timeliness.

(3) The invention has simple operation and low cost, and achieves the purposes of cost reduction and efficiency improvement.

The foregoing is a summary of the present invention, and the following is a detailed description of the preferred embodiments of the present invention in order to provide a more clear understanding of the technical features of the present invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic diagram of the calculation of weight coefficients for each pay zone using the "benchmark normalization method";

FIG. 2 is a schematic diagram illustrating the relationship between effective thickness encountered by the drill and the thickness of the perforations;

fig. 3 is a schematic diagram of a perforation position identification process.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The first embodiment is as follows:

a method for optimizing a multilayer tight sandstone gas reservoir perforation well section comprises the following steps,

the method comprises the following steps: acquiring static parameters of a gas well in a gas reservoir;

step two; converting each layer of gas production contribution rate of a gas well in a gas reservoir into a weight coefficient;

step three; establishing a single-layer comprehensive index by using the first step and the second step, and selecting a perforation layer by using the single-layer comprehensive index;

step four; determining the thickness of a perforation section according to the static parameters of the gas well obtained in the first step;

step five; judging the specific depth of the perforation well section according to the third step and the fourth step;

step six; and performing perforation according to the result obtained in the step five.

Further, the static parameters of the gas well in the first step comprise effective thickness, porosity, permeability, gas saturation and sand body interpretation conclusion.

Further, the gas production contribution rate of the gas well in the gas reservoir is converted into a weight coefficient by adopting a reference normalization method; the method comprises the following steps:

the first step is as follows: solving the drilling rate of each layer of the gas well;

the second step is that: taking the layer corresponding to the maximum drilling chance rate as a reference layer;

the third step: normalizing the gas production contribution rate of each layer of the gas well to a datum plane through the following formula:

each layer normalized value is the gas production contribution rate of each layer/the gas production contribution rate of the reference layer;

the fourth step: and respectively calculating the average value of the same-layer normalization values of all gas wells in the gas reservoir, wherein the calculated average value of the same-layer normalization values is the weight coefficient of each layer.

Furthermore, the first step of solving the drilling rate of each layer of the gas well is carried out by adopting the following formula

The drilling rate is the number of wells drilled to the layer/total number of wells in the gas reservoir.

Further, the specific method for selecting the perforation horizon in the third step comprises the following steps:

the first step is as follows: establishing a single layer composite index

The single-layer comprehensive index K is equal to the weight coefficient of each layer multiplied by the sand body coefficient multiplied by the effective thickness multiplied by the permeability multiplied by the porosity multiplied by the gas saturation;

the second step is that: and sequencing the comprehensive indexes of the single layers from large to small, and selecting the layer with the comprehensive index of each single layer positioned at the first 3-5 positions as a perforation layer.

Further, the sand body coefficient is a coefficient value assigned to each of the interpretation conclusions of the sand body, that is, the gas layer, the gas-containing water layer, and the dry layer, wherein the coefficient value of the gas layer is 1, the coefficient value of the gas-containing layer is 0.8, the coefficient value of the gas-containing layer is 0.5, the coefficient value of the gas-containing water layer is 0.2, and the coefficient value of the dry layer is 0.

Further, the thickness of the perforation section determined in the fourth step is obtained by adopting the following formula

The perforation thickness is 0.31 x effective thickness + 1.08.

Furthermore, the method for judging the specific perforation position of the perforation well section in the fifth step comprises the following steps,

the first step is as follows: extracting a natural gamma GR curve corresponding to the gas layer section;

the second step is that: determining a perforation position according to the GR curve obtained in the step one and the deposition type;

the third step: and determining the specific perforation position, analyzing the GR curve distribution trend, calculating the GR average value of the gas interval, and judging the position as the specific perforation depth when the GR value of 3 meters is less than the GR average value by 50%.

Furthermore, the method for determining the perforation area by combining the second step with the deposition type comprises the following steps: when the GR curve is bell-shaped, the sedimentary microfacies are riverway sedimentary with positive rhythm, and the perforation section is selected at the middle lower part of the sand body; when the GR curve is funnel-shaped, the sedimentary microfacies are sedimentary by a estuary sand dam or a bank overflow sand dam with reverse rhythm, and the perforation section is selected at the middle upper part of the sand body; when the GR curve is box-shaped, the deposition microphase is the deposition of the cardiac beach dam with the homogeneity law, and the perforation section is selected in the middle of the sand body.

During actual use, the gas production capacity of each layer system is determined, and quantitative analysis is performed by converting the gas production contribution rate into a weight coefficient. Firstly, applying static parameter test data of a gas well, setting a reference surface by adopting a 'reference normalization method', normalizing each layer of the single well to the reference surface, and averaging corresponding layer positions of each well to obtain an average gas production contribution ratio of each layer of the gas field as a weight coefficient.

And (3) integrating the interpretation conclusions of the sand body with multiple parameters such as effective thickness, porosity, permeability, gas saturation, gas layer/gas-water layer and the like of the drilling sand body, and establishing a single-layer optimal synthetic index, and an optimal perforation layer.

The formula: the single-layer comprehensive index K is equal to the weight coefficient of each layer multiplied by the sand body coefficient multiplied by the effective thickness multiplied by the permeability multiplied by the porosity multiplied by the gas saturation

And establishing a relation between the effective drilling thickness and the thickness of the perforation section, and integrating the drilling position, sand body interpretation and other data to finally determine the thickness of the perforation section.

The formula: perforation thickness is 0.31 multiplied by effective thickness +1.08

And identifying the deposition type according to the logging curve of the gas layer section, and preferably selecting specific positions of the perforating well section by judging the distribution trend of the curve.

In specific application, the method can be programmed by using EXCEL VB, can be used for unit and individual reference and application of perforation segment optimization, can be revised according to the actual production condition of each block, and has the advantages of small reduction of manpower and material resources and higher popularization.

The invention effectively reduces the interlayer interference, lays a solid foundation for the later-stage efficient high-quality large-scale production, and obtains considerable economic benefit and good social benefit.

Example two:

an example of practical application of a multilayer tight sandstone gas reservoir perforation well section optimization method.

1. And (4) determining the gas production capacity of each layer system, and performing quantitative analysis by converting the gas production contribution rate into a weight coefficient. Firstly, gas production profile test data is applied, a 'reference normalization method' is adopted, each layer of a single well is normalized to a reference surface by taking the box 8 as the reference surface, then the corresponding layer position of each well is averaged, and the average gas production contribution ratio of each layer of the gas field is obtained and is used as a weight coefficient (see figure 1).

2. And (4) integrating multiple parameters (effective thickness, porosity, permeability, gas saturation and sand body interpretation conclusion of the drilling encountering sand body), and establishing a single-layer optimal integration index, and an optimal perforation horizon.

The formula: the single-layer comprehensive index K is equal to the weight coefficient of each layer multiplied by the sand body coefficient multiplied by the effective thickness multiplied by the permeability multiplied by the porosity multiplied by the gas saturation

3. And establishing a relation between the effective drilling thickness and the thickness of the perforation section, and integrating the drilling position, sand body explanation and other data to finally determine the thickness of the perforation section (see figure 2).

The formula: perforation thickness is 0.31 multiplied by effective thickness +1.08

4. The deposit type is identified from the gas interval log, and the specific location of the perforated interval is preferred by identifying the distribution trend of the log (see fig. 3).

5. The EXCELVB program is used for realizing automatic optimization of the perforation well section, and after static data such as well numbers, geological stratification, sand body explanation and well logging curves are imported, perforation section optimization results including the number of perforation sections, perforation layers, specific positions and perforation optimization suggestions aiming at the conditions of a brook group, a water-containing gas layer or a sand body interval development argillaceous interlayer and the like can be automatically given.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

In the case of no conflict, a person skilled in the art may combine the related technical features in the above examples according to actual situations to achieve corresponding technical effects, and details of various combining situations are not described herein.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

The foregoing is illustrative of the preferred embodiments of the present invention, and the present invention is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Any simple modification, equivalent change and modification of the above embodiments according to the technical spirit of the present invention still fall within the scope of the technical solution of the present invention.

Claims (9)

1. A preferable method for a multilayer tight sandstone gas reservoir perforation well section is characterized by comprising the following steps,

the method comprises the following steps: acquiring static parameters of a gas well in a gas reservoir;

step two; converting each layer of gas production contribution rate of a gas well in a gas reservoir into a weight coefficient;

step three; establishing a single-layer comprehensive index by using the first step and the second step, and selecting a perforation layer by using the single-layer comprehensive index;

step four; determining the thickness of a perforation section according to the static parameters of the gas well obtained in the first step;

step five; judging the specific depth of the perforation well section according to the third step and the fourth step;

step six; and performing perforation according to the result obtained in the step five.

2. The method for optimizing the perforating well section of the multilayer tight sandstone gas reservoir as claimed in claim 1, wherein the method comprises the following steps: the static parameters of the gas well in the first step comprise effective thickness, porosity, permeability, gas saturation and sand body interpretation conclusion.

3. The method for optimizing the perforating well section of the multilayer tight sandstone gas reservoir as claimed in claim 1, wherein the method comprises the following steps: converting the gas production contribution rate of the gas well in the gas reservoir into a weight coefficient by adopting a reference normalization method; the method comprises the following steps:

the first step is as follows: solving the drilling rate of each layer of the gas well;

the second step is that: taking the layer corresponding to the maximum drilling chance rate as a reference layer;

the third step: normalizing the gas production contribution rate of each layer of the gas well to a datum plane through the following formula:

each layer normalized value is the gas production contribution rate of each layer/the gas production contribution rate of the reference layer;

the fourth step: and respectively calculating the average value of the same-layer normalization values of all gas wells in the gas reservoir, wherein the calculated average value of the same-layer normalization values is the weight coefficient of each layer.

4. The method for optimizing the perforating well section of the multilayer tight sandstone gas reservoir as claimed in claim 3, wherein the method comprises the following steps: the first step of solving the drilling rate of each layer of the gas well is carried out by adopting the following formula

The drilling rate is the number of wells drilled to the layer/total number of wells in the gas reservoir.

5. The method for optimizing the perforated well section of the multilayer tight sandstone gas reservoir according to claim 1, wherein the specific method for selecting the perforated horizon in the third step comprises the following steps:

the first step is as follows: establishing a single layer composite index

The single-layer comprehensive index K is equal to the weight coefficient of each layer multiplied by the sand body coefficient multiplied by the effective thickness multiplied by the permeability multiplied by the porosity multiplied by the gas saturation;

the second step is that: and sequencing the comprehensive indexes of the single layers from large to small, and selecting the layer with the comprehensive index of each single layer positioned at the first 3-5 positions as a perforation layer.

6. The method for optimizing the perforating well section of the multilayer tight sandstone gas reservoir as claimed in claim 5, wherein the method comprises the following steps: the sand body coefficient is the coefficient value corresponding to the interpretation conclusion of each sand body, namely, the gas layer, the gas-containing layer, the water-containing layer, the gas-containing water layer and the dry layer, wherein the coefficient value of the gas layer is 1, the coefficient value of the gas-containing layer is 0.8, the coefficient value of the water-containing layer is 0.5, the coefficient value of the gas-containing water layer is 0.2 and the coefficient value of the dry layer is 0.

7. The method for optimizing the perforated well section of the multilayer tight sandstone gas reservoir of claim 1, wherein the step four of determining the thickness of the perforated well section is obtained by adopting the following formula

The perforation thickness is 0.31 x effective thickness + 1.08.

8. The method for optimizing the perforating well section of the multilayer tight sandstone gas reservoir of claim 1, wherein the method for judging the specific perforating position of the perforating well section in the fifth step comprises the following steps,

the first step is as follows: extracting a natural gamma GR curve corresponding to the gas layer section;

the second step is that: determining a perforation position according to the GR curve obtained in the step one and the deposition type;

the third step: and determining the specific perforation position, analyzing the GR curve distribution trend, calculating the GR average value of the gas interval, and judging the position as the specific perforation depth when the GR value of 3 meters is less than the GR average value by 50%.

9. The method for optimizing the perforated well section of the multilayer tight sandstone gas reservoir of claim 8, wherein the second step of determining the perforated area by combining the deposition type comprises the following steps: when the GR curve is bell-shaped, the sedimentary microfacies are riverway sedimentary with positive rhythm, and the perforation section is selected at the middle lower part of the sand body; when the GR curve is funnel-shaped, the sedimentary microfacies are sedimentary by a estuary sand dam or a bank overflow sand dam with reverse rhythm, and the perforation section is selected at the middle upper part of the sand body; when the GR curve is box-shaped, the deposition microphase is the deposition of the cardiac beach dam with the homogeneity law, and the perforation section is selected in the middle of the sand body.

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