CN112392448B - Multi-layer system compact sandstone gas reservoir perforation well section optimization method - Google Patents

Abstract

The invention belongs to the technical field of multi-layer production of tight gas reservoirs, and particularly relates to a multi-layer tight sandstone gas reservoir perforation well section optimization method. According to the invention, six steps of acquiring 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 a weight coefficient, selecting a perforation layer position, determining the thickness of a perforation section, judging the specific depth of the perforation section and implementing perforation are adopted, the most reasonable perforation section is efficiently and accurately selected, the best transformation effect is achieved by using the selected perforation section, and the method has strong field applicability. The invention can combine the real-time parameter formula adjustment of the production progress, repeatedly verify the prediction result, and has stronger timeliness. The invention has simple operation and low cost, and really achieves the aims of reducing the cost and enhancing the efficiency.

Description

Multi-layer system compact sandstone gas reservoir perforation well section optimization method

Technical Field

The invention belongs to the technical field of multi-layer production of tight gas reservoirs, and particularly relates to a multi-layer tight sandstone gas reservoir perforation well section optimization method.

Background

Hypotonic tight sandstone reservoirs are widely distributed in many areas. However, as the production scale is continuously expanded, the geological conditions of the reservoir between wells are increasingly complex, interlayer interference exists among multiple layers in the vertical direction, and the production of the gas well is influenced by plane heterogeneity and vertical differentiation.

The perforation well section is an important factor influencing the development effect of a new well, and the selection of the reasonable perforation well section not only needs to realize the improvement of the utilization degree of the residual reserves in the heterogeneous gas reservoir, but also meets the requirements of the layer system development and the related gas production technology. Therefore, the preferable research on the perforation well section of the multi-layer system reservoir body is more refined, quantified and highly efficient, and the perforation well section is consistent with the actual production dynamic. Meanwhile, with the great reduction of the current oil price and the continuous increase of the environmental protection and land borrowing costs, the development cost of multilayer perforation fracturing transformation is improved intangibly, and the high-efficiency development of the gas field is seriously restricted. In order to ensure reasonable production of the gas well and maximum production cost reduction and efficiency improvement, how to select 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 system compact 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 perforation section position with high accuracy, high quality and high efficiency, providing reliable basis for perforation fracturing technology and ensuring that the yield of a new well is effectively and reasonably exerted.

A multi-layer system compact sandstone gas reservoir perforation well section optimization method,

step one: acquiring static parameters of a gas well in a gas reservoir;

step two, a step two is carried out; converting the gas production contribution rate of each layer of gas well in the gas reservoir into a weight coefficient;

step three, a step of performing; establishing a single-layer comprehensive index by utilizing the first step and the second step, and selecting a perforation horizon by utilizing the single-layer comprehensive index;

step four, a step four is carried out; determining the thickness of the perforating section according to the static parameters of the gas well obtained in the step one;

step five, a step of performing a step of; judging the specific depth of the shooting well section according to the third step and the fourth step;

step six, a step of performing a step of; and (3) perforating 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 a 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: solving the drilling meeting rate of each layer of the gas well;

and a second step of: taking a layer corresponding to the maximum drilling rate as a reference layer;

and a third step of: normalizing the gas production contribution rate of each layer of the gas well to a reference surface through the following formula:

each layer normalized value = each layer gas production contribution rate/reference layer gas production contribution rate;

fourth step: and respectively calculating the average value of the same-layer normalization values of all the 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 finding out the drilling meeting rate of each layer of the gas well is carried out by adopting the following formula

Drilling encounter rate = number of wells drilled to encounter the layer/total number of wells in the gas reservoir.

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

the first step: establishing a monolayer composite index

Single layer composite index k=weight coefficient of each layer×sand system number×effective thickness×permeability×porosity×gas saturation;

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

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

The fourth step of determining the thickness of the perforating section is obtained by adopting the following formula

Perforation thickness = 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: extracting a natural gamma GR curve corresponding to the gas layer section;

and a second step of: determining perforation positions according to the GR curve obtained in the step one and the deposition type;

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

The second step of determining the perforation area by combining the deposition type comprises the following steps: when the GR curve is bell-shaped, depositing a river course with a deposition microphase of positive rhythm, and selecting a perforation section at the middle lower part of the sand body; when the GR curve is funnel-shaped, the sediment microphase is deposited by a estuary sand dam or an spillover 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 sediment microphase is a beach dam sediment with a homogeneity law, and the perforating section is selected at the middle part of the sand body.

The beneficial effects are that:

(1) The method and the device have the advantages that the most reasonable perforation well sections are selected efficiently and accurately, the best transformation effect is achieved by using the optimal perforation sections, and the field applicability is high.

(2) The method combines the real-time parameter formula adjustment 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 aims of reducing the cost and enhancing the efficiency.

The foregoing description is only an overview of the technical solution of the present invention, and in order to make the technical means of the present invention more clearly understood, it can be implemented according to the content of the specification, and the following detailed description of the preferred embodiments of the present invention will be given.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are 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 other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of calculating weight coefficients of each production zone by adopting a reference normalization method;

FIG. 2 is a graphical illustration of the relationship between effective thickness of a drill and perforation thickness;

FIG. 3 is a schematic diagram of a perforation location determination process.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Embodiment one:

a multi-layer system compact sandstone gas reservoir perforation well section optimization method comprises the following steps,

step one: acquiring static parameters of a gas well in a gas reservoir;

step two, a step two is carried out; converting the gas production contribution rate of each layer of gas well in the gas reservoir into a weight coefficient;

step three, a step of performing; establishing a single-layer comprehensive index by utilizing the first step and the second step, and selecting a perforation horizon by utilizing the single-layer comprehensive index;

step four, a step four is carried out; determining the thickness of the perforating section according to the static parameters of the gas well obtained in the step one;

step five, a step of performing a step of; judging the specific depth of the shooting well section according to the third step and the fourth step;

step six, a step of performing a step of; and (3) perforating 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 second step is to convert 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: solving the drilling meeting rate of each layer of the gas well;

and a second step of: taking a layer corresponding to the maximum drilling rate as a reference layer;

and a third step of: normalizing the gas production contribution rate of each layer of the gas well to a reference surface through the following formula:

each layer normalized value = each layer gas production contribution rate/reference layer gas production contribution rate;

fourth step: and respectively calculating the average value of the same-layer normalization values of all the 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 obtaining the drilling meeting rate of each layer of the gas well is carried out by adopting the following formula

Drilling encounter rate = number of wells drilled to encounter the layer/total number of wells in the gas reservoir.

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

the first step: establishing a monolayer composite index

Single layer composite index k=weight coefficient of each layer×sand system number×effective thickness×permeability×porosity×gas saturation;

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

Further, the sand body coefficient is to assign corresponding coefficient values to each sand body interpretation conclusion, namely, a gas layer, a gas-containing layer, a water-containing layer and a 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 water-containing 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

Perforation thickness = 0.31 x effective thickness +1.08.

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

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

and a second step of: determining perforation positions according to the GR curve obtained in the step one and the deposition type;

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

Further, 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, depositing a river course with a deposition microphase of positive rhythm, and selecting a perforation section at the middle lower part of the sand body; when the GR curve is funnel-shaped, the sediment microphase is deposited by a estuary sand dam or an spillover 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 sediment microphase is a beach dam sediment with a homogeneity law, and the perforating section is selected at the middle part of the sand body.

In practical 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, adopting a reference normalization method, setting a reference surface, normalizing each layer of a single well to the reference surface, and then averaging corresponding layers of each well to obtain average gas production contribution ratio of each layer of the gas field as a weight coefficient.

And establishing a single-layer preferred comprehensive index, and a preferred perforation layer by integrating multiple parameters such as effective thickness, porosity, permeability, gas saturation, gas layer/gas-containing layer/gas-water same layer and other sand body interpretation conclusion of the drilling sand body.

The formula: single layer composite index k=weight coefficient of each layer×sand system number×effective thickness×permeability×porosity×gas saturation

And establishing the relation between the effective thickness of the drill and the thickness of the perforating section, comprehensively drilling the information such as the interpretation of the layer and the sand body, and finally determining the thickness of the perforating section.

The formula: perforation thickness = 0.31 x effective thickness +1.08

And identifying the deposition type according to the logging curve of the gas layer section, and optimizing the specific position of the perforation well section by judging the distribution trend of the curve.

In specific application, the invention can also be programmed by adopting the EXCEL VB, can be used for developing the unit and the individual reference and application of perforation section optimization, can be revised according to the actual production condition of each block, has less manpower and material resources and higher popularization.

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

Embodiment two:

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

1. 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, gas production profile test data are applied, a reference normalization method is adopted, each layer of a single well is normalized to a reference plane by taking a box 8 as the reference plane, and then the corresponding layers of each well are averaged to obtain the average gas production contribution ratio of each layer of the gas field as a weight coefficient (see figure 1).

2. And (3) integrating multiple parameters (effective thickness, porosity, permeability, gas saturation and sand interpretation conclusion of the drilling sand body), and establishing a single-layer preferential comprehensive index, and a preferential perforation layer.

The formula: single layer composite index k=weight coefficient of each layer×sand system number×effective thickness×permeability×porosity×gas saturation

3. And establishing a relation between the effective thickness of the drill and the thickness of the perforating section, and comprehensively drilling the information such as the interpretation of the layers and the sand body, and finally determining the thickness of the perforating section (see figure 2).

The formula: perforation thickness = 0.31 x effective thickness +1.08

4. The deposit type is identified according to the logging curve of the gas layer section, and the specific position of the perforation well section is preferred by identifying the distribution trend of the curve (see figure 3).

5. The automatic optimization of the perforation well section is realized by using the EXCELVB program, and after static data such as well numbers, geological layering, sand body interpretation, well logging curves and the like are imported, perforation section optimization results including perforation section numbers, perforation layers, specific positions, perforation optimization suggestions for the conditions of developing a muddy interlayer among the present stream group, water-bearing gas layer or sand bodies and the like can be automatically given.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Under the condition of no conflict, the technical features related to the examples can be combined with each other according to actual situations by a person skilled in the art so as to achieve corresponding technical effects, and specific details of the combination situations are not described in detail herein.

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

While the invention is susceptible of embodiments in accordance with the preferred embodiments, the invention is not intended 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 variation and modification of the above embodiments according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

Claims (7)

1. A multi-layer system compact sandstone gas reservoir perforation well section optimization method is characterized by comprising the following steps,

step one: acquiring static parameters of a gas well in a gas reservoir;

step two, a step two is carried out; converting the gas production contribution rate of each layer of gas well in the gas reservoir into a weight coefficient;

step three, a step of performing; establishing a single-layer comprehensive index by utilizing the first step and the second step, and selecting a perforation horizon by utilizing the single-layer comprehensive index;

step four, a step four is carried out; determining the thickness of the perforating section according to the static parameters of the gas well obtained in the step one;

step five, a step of performing a step of; judging the specific depth of the shooting well section according to the third step and the fourth step;

step six, a step of performing a step of; according to the result obtained in the fifth step, perforating is implemented;

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

the first step: establishing a monolayer composite index

Single layer composite index k=weight coefficient of each layer×sand system number×effective thickness×permeability×porosity×gas saturation;

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

converting the gas production contribution rate of a 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: solving the drilling meeting rate of each layer of the gas well;

and a second step of: taking a layer corresponding to the maximum drilling rate as a reference layer;

and a third step of: normalizing the gas production contribution rate of each layer of the gas well to a reference surface through the following formula:

each layer normalized value = each layer gas production contribution rate/reference layer gas production contribution rate;

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

2. A multi-layer tight sandstone gas reservoir perforation interval optimization method as claimed in claim 1, wherein: the static parameters of the gas well in the first step comprise effective thickness, porosity, permeability, gas saturation and sand body interpretation conclusion.

3. A multi-layer tight sandstone gas reservoir perforation interval optimization method as claimed in claim 1, wherein: the first step of finding out the drilling meeting rate of each layer of the gas well is carried out by adopting the following formula

Drilling encounter rate = number of wells drilled to encounter the layer/total number of wells in the gas reservoir.

4. A multi-layer tight sandstone gas reservoir perforation interval optimization method as claimed in claim 1, wherein: the sand body coefficient is to give corresponding coefficient value to each sand body interpretation conclusion, namely, gas layer, gas-containing layer, water-containing layer and 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 water-containing layer is 0.2 and the coefficient value of the dry layer is 0.

5. The method for optimizing a perforation interval of a multi-layer tight sandstone gas reservoir according to claim 1, wherein the thickness of the perforation interval is determined by the following formula

Perforation thickness = 0.31 x effective thickness +1.08.

6. The method for optimizing the perforation interval of the multi-layer tight sandstone gas reservoir according to claim 1, wherein the method for judging the perforation specific position of the perforation interval in the fifth step comprises the following steps,

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

and a second step of: determining perforation positions according to the GR curve obtained in the step one and the deposition type;

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

7. A multi-layer tight sandstone gas reservoir perforation interval optimization method as claimed in claim 6, wherein said second step of determining perforation areas in combination with deposition types comprises the steps of: when the GR curve is bell-shaped, depositing a river course with a deposition microphase of positive rhythm, and selecting a perforation section at the middle lower part of the sand body; when the GR curve is funnel-shaped, the sediment microphase is deposited by a estuary sand dam or an spillover 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 sediment microphase is a beach dam sediment with a homogeneity law, and the perforating section is selected at the middle part of the sand body.

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