A quantitative characterization method for dynamic changes of recovery degree components during waterflooding reservoir development

Abstract

The present invention discloses a quantitative characterization method for the dynamic changes of the recovery degree of a water-flooding reservoir. The recovery degree of a stage is decomposed by five parameters, namely, the oil displacement efficiency, the plane sweep coefficient, the longitudinal sweep coefficient, the water-flooding reserve control degree and the water-flooding reserve utilization degree, to obtain the curves of the changes of different parameters with the water content. Through the dynamic decomposition study of the recovery degree of a stage: first, the characteristic parameters of the production increase measures with different action mechanisms can be deeply analyzed. By comparing the changes of various parameters in the recovery degree of the stage before and after the measures, compared with the current general evaluation method, this method is more detailed and targeted in evaluating parameters; second, the main development contradictions of oil reservoirs at different water-containing stages can be clarified.

Description

Technical Field

[0001] The invention belongs to the technical field of oil reservoir engineering in oil and gas field development, and in particular relates to a quantitative characterization method for dynamic changes in the production degree composition in the water injection development stage of an oil reservoir. Background Art

[0002] At present, water injection development, which uses water injection to maintain reservoir pressure, is widely used at home and abroad. Stage recovery refers to the percentage of the cumulative oil or gas production of an oil and gas field at a certain time to the geological reserves. For water injection development of oil reservoirs, the relationship between stage recovery and comprehensive water content is usually used to study the water drive characteristics of the reservoir and predict the recovery rate. However, there is no decomposition study on the composition of stage recovery. At different stages of oil field development, in order to improve the development effect, the plan is usually adjusted or production increase measures are taken, including injection and production adjustment, fine stratified water injection, well network density, profile adjustment and water plugging, or tertiary oil recovery related enhanced recovery technology, etc. When evaluating the effect of production increase measures, parameters such as cumulative oil increase, decline, formation pressure maintenance level, and stage recovery are usually used for evaluation. However, due to the different mechanisms of production increase of different technologies, such as the main purpose of well network density adjustment is to improve the plane sweep coefficient, when evaluating the effect, more attention should be paid to evaluating the improvement of the plane sweep coefficient and its contribution to the stage recovery. However, the existing evaluation methods for the effectiveness of production-increasing measures are too simple and general, and cannot achieve a targeted evaluation of the effectiveness of the measures, resulting in insufficient understanding of the adaptability of the technology in the reservoir. Therefore, it is necessary to analyze from the perspective of the composition changes of the stage recovery degree, compare the changes in the stage oil displacement efficiency, stage sweep coefficient, stage plane sweep coefficient, and stage longitudinal sweep coefficient before and after the measures, and target evaluate the effectiveness of the measures and the adaptability of the technology. Summary of the invention

[0003] In view of the problem that the current evaluation methods for the effects of different production-increasing measures in waterflooding development of oil reservoirs are too simple and general, and cannot achieve targeted evaluation of the effects of measures, resulting in a lack of in-depth understanding of the adaptability of technologies in oil reservoirs, a quantitative characterization method for the dynamic changes in the recovery degree composition during the waterflooding development of oil reservoirs was proposed, which provided a method for a deeper understanding of the adaptability of different technologies.

[0004] To achieve the above-mentioned purpose, the present invention discloses a quantitative characterization method for the dynamic change of stage recovery degree with water cut by combining actual reservoir production dynamic data, water absorption profile test data and water drive oil relative permeability data. The stage recovery degree is decomposed into five parameters: stage oil recovery efficiency, plane sweep coefficient, longitudinal sweep coefficient, water drive reserve control degree and water drive reserve utilization degree, and curves of the change of different parameters with water cut are obtained.

[0005] The following steps are involved:

[0006] Step 1: Calculate the stage recovery degree according to the ratio of the cumulative oil production and geological reserves of the target reservoir, block or measure well group, and obtain the stage recovery degree-water content curve;

[0007] Step 2: According to the relative permeability curves of different core water flooding oil in the target reservoir or block, the normalized calculation of the phase permeability curve is performed to obtain the relative permeability curve representing the target block. According to the phase permeability curve of the block, the water content at different water saturations is calculated according to the flow equation, and then according to the water saturation , Irreducible water saturation , residual oil saturation Calculate the stage oil displacement efficiency and obtain the stage oil displacement efficiency-water content curve;

[0008] Step 3, calculating the stage sweep coefficient according to the stage recovery degree-water content curve obtained in step 1 and the stage oil displacement efficiency-water content curve obtained in step 2, and obtaining the stage sweep coefficient-water content curve;

[0009] Step 4, calculating the water drive reserve control degree at different water content stages, and obtaining a stage water drive reserve control degree-water content curve;

[0010] Step 5, calculating the utilization degree of stage water drive reserves under different water cuts, and obtaining the stage water drive reserves utilization degree-water cut curve;

[0011] Step 6, calculating the stage longitudinal sweep coefficient according to the stage water drive reserve control degree obtained in step 4 and the stage water drive reserve utilization degree obtained in step 5, and obtaining a stage longitudinal sweep coefficient-water content curve;

[0012] Step 7: Calculate the stage plane sweep coefficient according to the stage sweep coefficient obtained in step 3 and the stage longitudinal sweep coefficient obtained in step 6 to obtain a stage plane sweep coefficient-water content curve.

[0013] Further, step 2 includes the following steps:

[0014] S1. According to the relative permeability curves of water flooding of different cores of the target reservoir or block, normalization calculation of the phase permeability curve is performed to obtain a relative permeability curve representing the block;

[0015] S2. Calculate the water content at different water saturations according to the phase permeability curve of the block and the flow rate equation, and then calculate the water content at different water saturations according to the water saturation. , Irreducible water saturation , residual oil saturation Calculate the stage oil displacement efficiency and obtain the stage oil displacement efficiency-water content curve;

[0016] Stage oil recovery efficiency The calculation formula is: .

[0017] Furthermore, in step 3, the stage sweep coefficient is equal to the stage recovery degree divided by the stage displacement efficiency.

[0018] Furthermore, in step 4, the stage water drive reserve control degree is equal to the cumulative perforated layer thickness at different water cut stages divided by the cumulative reservoir oil layer thickness.

[0019] Furthermore, in step 5, the utilization degree of the stage water drive reserves is equal to the cumulative water absorption thickness interpreted by all water absorption profile tests of the block at different water content stages divided by the cumulative oil layer thickness.

[0020] Furthermore, in step 6, the stage longitudinal sweep coefficient is equal to the stage water drive reserve control degree obtained in step 4 multiplied by the stage water drive reserve utilization degree determined in step 5.

[0021] Furthermore, in step 7, the stage plane sweep coefficient is equal to the stage sweep coefficient obtained in step 3 divided by the stage longitudinal sweep coefficient determined in step 6.

[0022] Through the above process, the stage recovery degree can be decomposed into the stage oil displacement efficiency, plane sweep coefficient, longitudinal sweep coefficient, water drive reserve control degree and water drive reserve utilization degree, and the change curve of different parameters with water content can be obtained. By comparing the changes of various parameters before and after the measures, the effect of the measures can be evaluated in a targeted manner.

[0023] Compared with the prior art, the present invention has at least the following beneficial technical effects. The present invention proposes a quantitative characterization method for the dynamic change of the stage recovery degree composition with water content by combining the actual reservoir production dynamic data, water absorption profile test data and water drive oil relative permeability data. The change curve of the five parameters of stage oil displacement efficiency, plane sweep coefficient, longitudinal sweep coefficient, water drive reserve control degree and water drive reserve utilization degree with water content characterizes the change of the stage recovery degree composition. Through the dynamic decomposition study of the stage recovery degree composition: first, it can deeply analyze the characteristic parameters of the production increase measures with different action mechanisms. By comparing the changes of various parameters in the stage recovery degree before and after the measures, compared with the current general evaluation method, this method evaluates the parameters more detailed and targeted; second, it clarifies the main development contradictions of oil reservoirs at different water content stages. If the plane sweep coefficient is low, the direction of the later measures should be mainly to improve the plane sweep coefficient; if the water drive reserve control degree is low, the direction of the later measures should be mainly to improve the water drive reserve control degree by filling holes. By comparing the changes in the recovery degree before and after the measures, we can more accurately evaluate the contribution of different parameters to the cumulative increase in oil production, more clearly identify the adaptability of the technology to reservoirs with different development contradictions, achieve accurate matching of different technologies and development contradictions, and evaluate the effects of different measures in a targeted manner, providing a quantitative basis for a deeper understanding of the adaptability of different technologies. At the same time, according to the size of each parameter at different water-cut stages, we can clarify the main contradictions at different development stages and the main direction for improving development effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A decomposition flow chart is formed for the stage extraction degree. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] Reference Figure 1 A quantitative characterization method for the dynamic change of the stage recovery degree with water cut based on the actual reservoir production dynamic data, water absorption profile test data and water drive oil relative permeability data is proposed. The stage recovery degree is decomposed by five parameters, namely, stage oil drive efficiency, plane sweep coefficient, longitudinal sweep coefficient, water drive reserve control degree and water drive reserve utilization degree, to obtain the change curves of different parameters with water cut. The calculation method of different dynamic change curves includes the following steps:

[0028] (1) Calculation of stage recovery degree-water cut curve: Based on the actual production dynamic data of the target reservoir, block or well group, the stage recovery degree is calculated by the ratio of cumulative oil production to geological reserves to obtain the stage recovery degree-water cut relationship;

[0029] (2) Calculation stage: Water-to-oil efficiency-water content curve: Select the relative permeability curves of different cores representing the target reservoir and block, perform normalization calculation of the phase permeability curve, and obtain the relative permeability curve representing the block. Calculate the water content at different water saturations according to the phase permeability curve of the block according to the flow equation, and then calculate the water content at different water saturations according to the water saturation. , Irreducible water saturation , residual oil saturation Calculate the stage oil recovery efficiency and obtain the stage oil recovery efficiency-water content curve, which can represent the average oil recovery efficiency in the water injection affected area at different water content stages;

[0030] The calculation formula of stage displacement efficiency is: ;

[0031] In the above formula: is water saturation; is the bound water saturation, is the residual oil saturation, is the stage oil recovery efficiency (water saturation is Oil displacement efficiency at 100 ℃ It is the oil recovery efficiency at the end of water flooding (oil recovery efficiency at maximum water saturation).

[0032] (3) Calculating the stage sweep coefficient-water cut curve: Based on the stage recovery degree-water cut curve obtained in (1) and the stage displacement efficiency-water cut curve obtained in (2), at the same water cut, calculate the stage sweep coefficient to obtain the stage sweep coefficient-water cut curve;

[0033] Stage sweep coefficient = stage recovery degree / stage oil recovery efficiency;

[0034] (4) Statistical stage water drive reserve control degree-water cut curve: Calculate the water drive reserve control degree at different water cut stages to obtain the stage water drive reserve control degree-water cut curve;

[0035] The degree of control of water drive reserves at different stages = the cumulative thickness of perforated layers at different water content stages / the cumulative thickness of oil reservoir layers.

[0036] (5) Statistical analysis of the stage water drive reserve utilization degree-water cut curve: Calculate the stage water drive reserve utilization degree under different water cuts to obtain the stage water drive reserve control degree-water cut curve;

[0037] The utilization degree of water drive reserves at different stages = the cumulative water absorption thickness interpreted by all water absorption profile tests of the block at different water content stages / the cumulative oil layer thickness;

[0038] (6) Calculating the stage longitudinal sweep coefficient-water content curve: Calculate the stage longitudinal sweep coefficient to obtain the stage longitudinal sweep coefficient-water content curve;

[0039] Stage longitudinal sweep coefficient = (4) obtained stage water drive reserve control degree × (5) determined stage water drive reserve utilization degree;

[0040] (7) Determine the stage plane sweep coefficient-water content curve: Calculate the stage plane sweep coefficient to obtain the stage plane sweep coefficient-water content curve.

[0041] The stage plane sweep coefficient = the stage sweep coefficient calculated by (3) / the stage longitudinal sweep coefficient determined by (6).

[0042] Through the above process, the stage recovery degree can be decomposed into stage oil displacement efficiency, plane sweep coefficient, longitudinal sweep coefficient, water drive reserve control degree and water drive reserve utilization degree, and the change curves of the above five parameters with water cut can be obtained.

[0043] Stage recovery degree = stage oil displacement efficiency × stage swept volume;

[0044] Stage sweep volume = stage plane sweep volume × stage longitudinal sweep volume;

[0045] The vertical swept volume of the stage = the utilization degree of water drive reserves of the stage × the control degree of water drive reserves of the stage;

[0046] The utilization degree of water drive reserves at different stages = the cumulative water absorption thickness interpreted by all water absorption profile tests of the block at different water content stages / the cumulative oil layer thickness at different stages;

[0047] The degree of water drive reserve control in a certain stage = the cumulative thickness of perforated layers in that stage / the cumulative thickness of oil layers in that stage.

[0048] When the stage recovery efficiency is low, it is recommended to change the injection medium to improve the recovery efficiency, including injection of surfactants, gas injection (CO2, N2 or natural gas, etc.);

[0049] When the plane sweep coefficient is low, it is recommended to increase the plane sweep coefficient through injection-production adjustment, well pattern densification and other measures;

[0050] When the longitudinal sweep coefficient is low, it is recommended to increase the longitudinal sweep coefficient by means of water injection well profile adjustment, oil well water plugging, stratified water injection, stratified production, etc.

[0051] When the water drive reserve control degree is low, it is recommended to increase the perforation thickness by selecting layers for perforation and improve the water drive reserve control degree;

[0052] When the utilization rate of water drive reserves is low, it is recommended to increase the water absorption thickness through water injection well profile control and stratified water injection to improve the utilization rate of water drive reserves.

[0053] By using the above-mentioned curve of water content changing with water content rate, we can clarify the main development contradictions of oil reservoirs in different water content stages and the adjustment direction of development policies, and at the same time, we can evaluate the effects of different production increase measures in a targeted manner and improve the pertinence of the evaluation.

[0054] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A quantitative characterization method for dynamic changes in the recovery degree of an oil reservoir during water flooding development, characterized in that: The stage recovery degree is decomposed into five parameters: stage oil displacement efficiency, plane sweep coefficient, longitudinal sweep coefficient, water drive reserve control degree and water drive reserve utilization degree, and the curves of different parameters changing with water cut are obtained. The following steps are involved: Step 1: Calculate the stage recovery degree according to the ratio of the cumulative oil production and geological reserves of the target reservoir, block or measure well group, and obtain the stage recovery degree-water content curve; Step 2: According to the relative permeability curves of different core water flooding oil in the target reservoir or block, the normalized calculation of the phase permeability curve is performed to obtain the relative permeability curve representing the target block. According to the phase permeability curve of the block, the water content at different water saturations is calculated according to the flow equation, and then according to the water saturation , Irreducible water saturation , residual oil saturation Calculate the stage oil displacement efficiency and obtain the stage oil displacement efficiency-water content curve; Step 3, calculating the stage sweep coefficient according to the stage recovery degree-water content curve obtained in step 1 and the stage oil displacement efficiency-water content curve obtained in step 2, and obtaining the stage sweep coefficient-water content curve; Step 4, calculating the water drive reserve control degree at different water content stages, and obtaining a stage water drive reserve control degree-water content curve; Step 5, calculating the utilization degree of stage water drive reserves under different water cuts, and obtaining the stage water drive reserves utilization degree-water cut curve; Step 6, calculating the stage longitudinal sweep coefficient according to the stage water drive reserve control degree obtained in step 4 and the stage water drive reserve utilization degree obtained in step 5, and obtaining a stage longitudinal sweep coefficient-water content curve; Step 7, calculating the stage plane sweep coefficient according to the stage sweep coefficient obtained in step 3 and the stage longitudinal sweep coefficient obtained in step 6, and obtaining a stage plane sweep coefficient-water content curve; Step 2 includes the following steps: S1. According to the relative permeability curves of water flooding of different cores of the target reservoir or block, normalization calculation of the phase permeability curve is performed to obtain a relative permeability curve representing the block; S2. Calculate the water content at different water saturations according to the phase permeability curve of the block and the flow rate equation, and then calculate the water content at different water saturations according to the water saturation. , Irreducible water saturation , residual oil saturation Calculate the stage oil displacement efficiency and obtain the stage oil displacement efficiency-water content curve; Stage oil recovery efficiency The calculation formula is: ; In step 4, the stage water drive reserve control degree is equal to the cumulative perforated layer thickness at different water cut stages divided by the cumulative reservoir oil layer thickness; In step 5, the utilization degree of stage water drive reserves is equal to the cumulative water absorption thickness interpreted by all water absorption profile tests of the block at different water cut stages divided by the cumulative oil layer thickness.

2. The method for quantitatively characterizing the dynamic changes of the recovery degree of an oil reservoir during water flooding development according to claim 1, characterized in that: In step 3, the stage sweep coefficient is equal to the stage recovery degree divided by the stage displacement efficiency.

3. The method for quantitatively characterizing the dynamic changes of the recovery degree composition during the water flooding development of an oil reservoir according to claim 1, characterized in that: In step 6, the stage longitudinal sweep coefficient is equal to the stage water drive reserve control degree obtained in step 4 multiplied by the stage water drive reserve utilization degree determined in step 5.

4. The method for quantitatively characterizing the dynamic changes of the recovery degree composition during the water flooding development of an oil reservoir according to claim 1, characterized in that: In step 7, the stage plane sweep coefficient is equal to the stage sweep coefficient obtained in step 3 divided by the stage longitudinal sweep coefficient determined in step 6.

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