CN116044391A - Method for determining dosage of profile control agent of low permeability reservoir horizontal well - Google Patents

Abstract

The invention provides a method for determining the dosage of a profile control agent in a horizontal well of a low-permeability oil reservoir, and belongs to the technical field of oil field development. The method includes the following steps: obtaining the production data of the horizontal well and the geological data of the reservoir; obtaining the proportion of macropores in the reservoir and the oil production contribution rate of the high-permeability layer; Proportion and oil production contribution rate of high-permeability layers, and the amount of profile control agent is obtained through a predetermined algorithm. This method not only considers the adjustment depth and well spacing in the actual production process, but also considers the influence of the high permeability layer on the adjustment through the oil production rate and the proportion of the high permeability layer, and also considers the fracturing volume that is most easily ignored in the actual production process Compared with the traditional method, the difference between the final calculated result and the actual situation is small, and the accuracy is high. Therefore, it can guide the dosage of regulators in tight oil reservoirs and provide corresponding technical support for actual production.

Description

Method for Determining the Dosage of Profile Control Agent in Horizontal Wells in Low Permeability Reservoirs

technical field

The invention relates to the technical field of oil field development, in particular to a method for determining the dosage of a profile control agent for horizontal wells in low-permeability oil reservoirs.

Background technique

In the process of waterflooding in ultra-low permeability reservoirs, water flooding will inevitably occur, and the injected water rushes rapidly along the high-permeability channels, resulting in a series of problems such as ineffective circulation of injected water and decreased production of oil wells. In order to improve the water absorption profile, expand the swept volume of injected water, and increase water flooding recovery, a large number of laboratory experiments and field experiments have shown that the regulation of water injection wells is an effective means to solve the problem of water flooding. However, there is no authoritative calculation method for the dosage of regulators in the current horizontal well regulation process.

式中，V为调剖剂的注入量，立方米；R为调剖半径，m；L为注水井水平段长度，m；h为油层有效厚度，m；

为油层的孔隙度，无量纲；α为高渗透层厚度占油层厚度的百分数，无量纲；δ为方向系数，无量纲；β为调剖面积系数，无量纲。The existing calculation method is as follows

In the formula, V is the injection volume of profile control agent, cubic meters; R is the radius of profile control, m; L is the length of horizontal section of water injection well, m; h is the effective thickness of oil layer, m;

is the porosity of the oil layer, dimensionless; α is the percentage of the thickness of the high permeability layer to the thickness of the oil layer, dimensionless; δ is the direction coefficient, dimensionless; β is the profile control area coefficient, dimensionless.

However, the existing calculation methods do not take into account the artificially stimulated volume formed by the volumetric fracturing of horizontal wells; at the same time, the thickness of the high-permeability layer of the horizontal well is shorter than the length of the entire horizontal well section, and it is not easy to read in the horizontal well logging curve , and the effective sand body without oil in the reservoir also has permeability, but this method does not consider it. Therefore, the amount of profile control obtained by using this method is quite different from the actual situation, and it is difficult to apply it in actual engineering.

Contents of the invention

In order to solve at least one of the above-mentioned problems, the present invention proposes a method for determining the amount of profile control agent for horizontal wells in low-permeability reservoirs. The dosage of the regulating agent obtained by the method of the present invention has less difference from the actual situation and higher accuracy.

In order to achieve the above goals, the technical solution of the present invention is as follows: a method for determining the amount of profile control agent for horizontal wells in low-permeability reservoirs, comprising the following steps

S1. Obtain the production data and reservoir geological data of the horizontal well;

S2. Obtain the proportion of large pores in the reservoir and the oil production contribution rate of the high permeability layer;

式中，V_z为调控用量体积，m³；D为井距，m；h为有效砂体厚度，m；φ为有效砂体厚度对应的平均孔隙度，％；τ为调控深度系数，是指调控深度与相邻井距离的比值，范围为0～1；L_k1为高渗段长度，m；L为水平井水平段长度，m；V_k为水平井控制体积，m³；V_frc为压裂体积，m³；V_h为当前累计产油量，m³；V_b为油藏标定水驱采油量，m³；χ为高渗透层采油贡献率，％；η为大孔占比，无量纲。S3. Based on the production data of the horizontal well, the geological data of the reservoir, the proportion of macropores in the reservoir and the oil production contribution rate of the high-permeability layer, the dosage of the profile control agent is obtained through a predetermined algorithm, and the predetermined algorithm is as follows:

In the formula, V _z is the volume of control volume, m ³ ; D is the well spacing, m; h is the effective sand body thickness, m; φ is the average porosity corresponding to the effective sand body thickness, %; τ is the control depth coefficient, which is Refers to the ratio of the control depth to the distance between adjacent wells, ranging from 0 to 1; L _k1 is the length of the high-permeability section, m; L is the length of the horizontal section of the horizontal well, m; V _k is the control volume of the horizontal well, m ³ ; V _frc V _h is the current cumulative oil production, m ³ ; V _b is the calibrated water flooding oil production of the reservoir, m ³ ; χ is the contribution rate of high permeability ^layer to oil recovery, %; ratio, dimensionless.

Beneficial effects: the method of the present invention not only considers the control depth and well spacing in the actual production process, but also considers the influence of the high-permeability layer on the control through the oil production rate and the proportion of the high-permeability layer, and also considers the most in the actual production process. The effect of fracturing volume, which is easy to be ignored, is finally calculated to obtain the amount of regulator. Compared with the traditional method, the difference between the final calculated result and the actual situation is small, and the accuracy is high. Therefore, it can guide the dosage of regulators in tight oil reservoirs and provide corresponding technical support for actual production.

Description of drawings

Fig. 1 is a section view of horizontal well development horizons.

Fig. 2 is the oil production under different profile control depth coefficients in Example 1;

Fig. 3 is the water content under different profile control depth coefficients in Example 1.

Detailed ways

The specific implementation manners of the present invention will be clearly and completely described below in conjunction with examples. Apparently, the described examples are only some embodiments of the present invention, rather than all embodiments.

The present invention will be further described below in conjunction with embodiment:

In the following examples, unless otherwise specified, the operations described are conventional operations in the art.

S1. Obtain the production data and reservoir geological data of the horizontal well; wherein, the production data of the horizontal well includes the length of the horizontal well section, the control range of the horizontal well plane, the current cumulative oil production, and the water flooding calibrated oil production; the reservoir geological parameters include Artificial fracture stimulation volume, half-fracture length of fracture, effective sand body thickness of development layer, average porosity of horizontal section, percentage of high permeability section length to horizontal section length. These data can be obtained through simple well logging and lithology analysis, which is relatively easy.

S2. Obtain the proportion of large pores in the reservoir and the oil production contribution rate of the high permeability layer;

Among them, the proportion of macropores in the reservoir refers to the percentage of macropore volume to all pore volumes, which can be obtained through lithological analysis: for example, obtained from the ratio of the macropore area of the NMR T2 spectrum to the total area of the spectrum; or , the boundary of macropores is defined by NMR, and the proportion coefficient of macropores is obtained by pore size distribution. At the same time, the macropores in the embodiments of the present invention refer to macroscopic pores in nuclear magnetic spectrum.

For the reservoir, it is usually heterogeneous. Therefore, the hyperpermeable layer referred to in the embodiments of the present invention refers to a reservoir that is 10 times greater than the minimum permeability of the reservoir, that is, the relative permeability when the permeability difference is 10. hypertonic layer. The percentage of oil production in high permeability layer to cumulative oil production can be obtained by parallel core flooding experiments, heterogeneous multi-layer permeability core flooding experiments, nuclear magnetic scanning experiments or numerical simulation methods. All belong to the prior art in this field, therefore.

S3. Based on the production data of the horizontal well, the geological data of the reservoir, the proportion of macropores in the reservoir and the oil production contribution rate of the high-permeability layer, the dosage of the profile control agent is obtained through a predetermined algorithm, and the predetermined algorithm is as follows:

为有效砂体厚度对应的平均孔隙度，％；τ为调控深度系数，是指调控深度与相邻井距离的比值，范围为0～1；L_k1为高渗段长度，m；L为水平井水平段长度，m；V_k为水平井控制体积，m3；V_frc为压裂体积，m³；V_h为当前累计产油量，m³；V_b为油藏标定水驱采油量，m3；χ为高渗透层采油贡献率，％；η为大孔占比，无量纲。Among them, V _z is the control dosage volume, m ³ ; D is the well spacing, m; h is the effective sand body thickness, m;

is the average porosity corresponding to the effective sand body thickness, %; τ is the control depth coefficient, which refers to the ratio of the control depth to the distance between adjacent wells, ranging from 0 to 1; L _k1 is the length of the high-permeability section, m; Horizontal section length of the flat well, m; V _k is the controlled volume of the horizontal well, m3; V _frc is the fractured volume, ^m3 ; V _h is the current cumulative oil production, ^m3 ; V _b is the calibrated water flooding oil recovery of the reservoir, m3; χ is the oil recovery contribution rate of high permeability layers, %; η is the proportion of macropores, dimensionless.

As shown in Figure 1, in this implementation plan, the effective sand body thickness h of the development layer is regarded as the height of the control volume, which is obtained by dividing the thickness of the vertical well layers adjacent to the horizontal well and averaging, and the calculation method is that the horizontal well section to be measured is adjacent to The average thickness of two vertical wells in the layer where the horizontal well section is located, namely

In the actual production process, depending on the actual situation, the control depth coefficient τ is usually set to different values. For example, according to different lithology, fracture conditions and oil production conditions, in some wells, it is necessary to make the control depth larger, while In other wells, the control depth needs to be controlled within a certain level. Therefore, when calculating the above predetermined algorithm, those skilled in the art can set the corresponding τ value according to the actual situation on site.

In the above predetermined algorithm, not only the control depth and well spacing in the actual production process are considered, but also the influence of the high permeability layer on the control is considered through the oil production rate and the proportion of the high permeability layer, and the most easily ignored in the actual production process. The influence of the fracture volume, therefore, the final result is better in accuracy than the conventional method.

However, at present, the major oil fields usually determine the value of τ through field conditions and combined with production experience, and there is a certain error in the results obtained in this way. Therefore, in the embodiments of the present invention, more accurate results can be obtained by the following methods: When using the predetermined algorithm to calculate, set a number of different values of control depth coefficients commonly used in the field within the range of 0 to 1, and then calculate them separately to obtain multiple different control agent dosages, and then use conventional commercial The simulation software conducts control simulations, and finally selects a more cost-effective control method based on indicators such as the oil content and oil production rate of the produced fluid. The commercial simulation software can adopt CMG-Stars software commonly used in this field.

From the above description, it can be seen that the method for determining the amount of regulating agent for low-permeability horizontal wells provided by this embodiment takes into account the absolute regulating ability of the reservoir and the degree of water flooding of oil wells in different water breakthrough periods, so as to reasonably design the regulating dosage of horizontal wells Designed to meet the needs of on-site regulation.

Example 1

The average permeability of a reservoir development layer is 10mD, the average porosity is 10%, the horizontal well section length is 800m, the injection-production well spacing is 500m, and the effective sand body thickness of the reservoir is 10m. The development method is horizontal well volume fracturing, the fracturing volume is 63744m ³ , and the proportion of large pores is 0.35. According to statistics, the length of the high permeability layer accounts for 0.375 of the length of the horizontal well. The current cumulative oil production is 60410m ³ , and the water drive calibrated oil production It is 300000m ³ , and the oil recovery contribution rate of the high permeability layer is 0.7.

计算，其中，其相邻井距为500m，在调控深度为50m、100m、200m、300m、400m和500m时，调控深度系数分别为0.1、0.2、0.4、0.6、0.8、1，计算所需调剖剂用量为4789m³、9578m³、19156m³、28734m³、38312m³、47890m³。According to predetermined algorithm

calculation, where the spacing between adjacent wells is 500m, and when the control depths are 50m, 100m, 200m, 300m, 400m and 500m, the control depth coefficients are 0.1, 0.2, 0.4, 0.6, 0.8, 1, and the required adjustment The amount of agent used is 4789m ³ , 9578m ³ , 19156m ³ , 28734m ³ , 38312m ³ , 47890m ³ .

The injection-production well pattern water flooding model was established by CMG-Stars software, and the profile control effect of different control depths was simulated. As shown in Figure 2 and Figure 3, it shows the relationship between oil production and water content of produced fluid with time under different control depth coefficients. It can be seen from the figure that when the control depth coefficient is 0.8, the production The oil volume is high, and the water content of the produced fluid is relatively low. At present, the economy is high, so the preferred results are: the control depth coefficient is 0.8, and the control agent dosage is 38312m ³ .

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes. Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence still belong to the scope of the technical solution of the present invention.

Claims (6)

1. A method for determining the amount of profile control agent for horizontal wells in low-permeability reservoirs, characterized in that it may further comprise the steps: S1. Obtain the production data and reservoir geological data of the horizontal well; S2. Obtain the proportion of large pores in the reservoir and the oil production contribution rate of the high permeability layer; S3. Based on the production data of the horizontal well, the geological data of the reservoir, the proportion of macropores in the reservoir and the oil production contribution rate of the high-permeability layer, the dosage of the profile control agent is obtained through a predetermined algorithm, and the predetermined algorithm is as follows:

In the formula, V _z is the volume of control volume, m ³ ; D is the well spacing, m; h is the effective sand body thickness, m; φ is the average porosity corresponding to the effective sand body thickness, %; τ is the control depth coefficient, which is Refers to the ratio of the control depth to the distance between adjacent wells, ranging from 0 to 1; L _k1 is the length of the high-permeability section, m; L is the length of the horizontal section of the horizontal well, m; V _k is the control volume of the horizontal well, m ³ ; V _frc V _h is the current cumulative oil production, m ³ ; V _b is the calibrated water ^flooding oil production of the reservoir, m ³ ; χ is the contribution rate of high permeability layer to oil recovery, %; ratio, dimensionless. 2. The method according to claim 1, characterized in that, the macropore ratio of the reservoir is obtained by the ratio of the macropore area of the NMR T2 spectrogram and the total area of the spectrogram; or, the macropore is defined by the NMR Boundary, the macropore proportion coefficient is obtained through the pore size distribution. 3. The method according to claim 1, wherein the oil recovery contribution rate of the high permeability layer is obtained by parallel core displacement experiments, heterogeneous multi-layer permeability core displacement experiments, nuclear magnetic scanning experiments or numerical simulation methods . 4. The method according to claim 3, characterized in that the oil recovery contribution rate of the high permeability layer is: the ratio of the cumulative oil recovery rate of the high permeability layer to the cumulative oil produced. 5. The method according to claim 1, characterized in that, the effective sand body thickness refers to the average value of the thicknesses of two adjacent vertical wells in the horizontal well section to be measured in the horizon where the horizontal well section is located. 6. The method according to claim 1, characterized in that multiple dosages of the profile control agent are obtained by setting multiple values of the control depth coefficients, and then the software CMG-Stars is used to optimize the dosage of the profile control agent.

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