A method for drawing thickness limit chart of chemical flooding layer combination

Abstract

The present invention relates to the field of tertiary oil recovery, and in particular belongs to a method for drawing a thickness limit map of a chemical drive layer system combination. The present invention comprises the following steps: step 1: data preparation; step 2: calculating the geological reserves per unit area and per unit thickness; step 3: calculating the oil production per unit thickness of a single well; step 4: calculating fixed costs and operating costs; step 5: calculating total costs; step 6: calculating crude oil revenue using a segmentation method; step 7: drawing a thickness limit map of a layer system combination. The present invention can draw a thickness limit map of a chemical drive layer system combination with different oil prices, different well spacings, and different enhanced oil recovery factors, which has a reference effect on the preparation of oilfield development plans, can improve the thickness accuracy and work efficiency of the layer system combination, make the layer system combination more reasonable, and has great application value.

Description

Technical Field

[0001] The invention relates to the field of tertiary oil recovery, and in particular belongs to a method for drawing a chemical flooding layer combination thickness limit plate. Background Art

[0002] In the process of formulating chemical flooding scheme, it is necessary to optimize the target layer and determine the appropriate layer combination thickness. The geological conditions of different blocks vary greatly, the well spacing varies, the oil price is complex and changeable, and the effect of improving oil recovery is different, which has a great impact on the combination thickness limit. A chemical flooding layer combination thickness limit chart that can be applied to various types of blocks is needed to improve the accuracy of the combination thickness and work efficiency.

[0003] At present, some methods of applying economic evaluation theory to determine the combined thickness limits of chemical drive formations have been reported at home and abroad. However, these methods are all combined thickness limits under one or two specific conditions. They fail to consider the impact of differences in reserve abundance between different blocks on the thickness limit, and fail to fully consider factors such as well spacing, oil prices, internal rate of return, and enhanced oil recovery. The research is incomplete, the error is large, the scope of application is narrow, and there is no combined thickness limit chart that can be applied to various types of blocks and different well spacings, making it difficult to quickly promote and apply it in oil fields.

[0004] To this end, parameters such as reserve abundance and well spacing were introduced to make the thickness limit of the layer combination applicable to different types of oil fields and different well spacing conditions, expanding the scope of application. Parameters such as different oil prices, different enhanced oil recovery factors, and internal rates of return were comprehensively considered, and the factors were comprehensively considered to improve the accuracy of the calculation results. Summary of the invention

[0005] In order to improve the application scope and accuracy of chemical drive layer combination thickness limit map, the present invention provides a method for drawing a chemical drive layer combination thickness limit map, which can quickly and accurately determine the layer combination thickness limits of different oil prices, different well spacings, and different enhanced oil recovery values, and is suitable for various oil field types, well spacing conditions and oil price levels.

[0006] The specific technical solution is as follows: A method for drawing a chemical flooding layer combination thickness limit map, comprising the following steps:

[0007] Step 1: Data preparation;

[0008] Step 2: Apply the original oil saturation of the block to calculate the geological reserves per unit area and unit thickness, that is, the reserve abundance;

[0009] Step 3: According to different well spacings, apply the definition of well pattern density to calculate the number of wells per unit area and the controlled geological reserves per unit thickness of a single well;

[0010] Step 4: Calculate fixed costs and operating costs, where operating costs are a function of oil production and are determined by trial calculation in step 7;

[0011] Step 5: Calculate the total cost, of which the operating cost will be determined after the trial calculation in step 7;

[0012] Step 6: Calculate the crude oil sales revenue at different oil prices using the segmentation method, and the oil production will be determined after the trial calculation in step 7;

[0013] Step 7: Use the trial calculation method to calculate the oil production of different layer combination thicknesses, and then calculate the operating cost, total cost and crude oil sales revenue; when the crude oil sales revenue and total cost are equal, the single well cumulative oil production limit is the single well cumulative oil production limit, and the combination thickness at this time is the layer combination thickness limit; according to the above method, the layer combination thickness limits at different enhanced oil recovery factors, different well spacings and different oil prices are obtained, and the layer combination thickness limit chart is drawn.

[0014] The specific steps of step 1 are: preparing fixed cost parameters such as original oil saturation of the target block, operating cost, drilling cost, ground construction investment and fracturing cost.

[0015] The specific method of step 2 is: calculate the geological reserves per unit area and unit thickness based on the original oil saturation:

[0016]

[0017] Where: N p is the geological reserves per unit area and unit thickness; S A is the unit area, i.e. 1km 2 ; h is the unit thickness, i.e. 1m; is the porosity; S oi is the original oil saturation; ρ o is the density of crude oil.

[0018] The specific method of step 3 is: calculate the controlled geological reserves per unit thickness of a single well:

[0019] n=S A / S well

[0020] N w =N P / n

[0021] N pj =ηN w

[0022] Where: S well is the single well control area; N w is the controlled geological reserves per unit thickness of a single well; n is the number of wells per unit area, N pjis the oil production per unit thickness of a single well, and η is the recovery factor.

[0023] The specific method of step 4 is: according to the oilfield economic evaluation parameters, calculate the fixed investment cost P of a single well respectively. g and operating cost P c ; Among them, the operating cost P g It is a function of oil production and is determined by trial calculation in step 7.

[0024] The specific method of step 5 is: in order to ensure that the calculated combined thickness limit can ensure good economic benefits, the internal rate of return is introduced to calculate the total cost:

[0025]

[0026] Where: P a is the total cost; P c (C P ) is the operating cost; R is the loan interest rate; C is the internal rate of return; t is the development evaluation period; j is the jth year in the evaluation period.

[0027] The specific method of step 6 is: calculate the crude oil sales revenue at different oil prices:

[0028]

[0029] Where: R s is sales revenue, q o is the initial daily oil production of the new well, γ is the annual production rate, C r is the crude oil commodity rate; P o is the crude oil price; N 1 N is the last production period; 2 It is the stable production period; N 3 is the decreasing period; C is the internal rate of return; s 0 is the rate of increase in output; D 0 is the natural decline rate; t is the evaluation period; P s (C P ) are various taxes.

[0030] The beneficial effects of the present invention are:

[0031] The present invention introduces the reserve abundance parameter to make the stratum combination thickness limit applicable to blocks with different oil layer conditions; the present invention introduces the well spacing parameter to calculate the stratum combination thickness limit of different well spacings; comprehensively considers different oil prices, different enhanced oil recovery factors, and internal rates of return, so that the calculation results are more reasonable. The chemical flooding stratum combination thickness limit chart drawn by the present invention can be applied to different types of oil fields; it can be quickly applied without repeated calculations; the calculation results are reasonable and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Draw the process of thickness limit chart for chemical flooding layer combination;

[0033] Figure 2 This is a chart showing the thickness limits of the strata combination in a certain block under the conditions of a well spacing of 125m and a chemical flooding enhanced oil recovery of 10%. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] The present invention provides a method for drawing a chemical flooding layer combination thickness limit map, the method comprising the following steps:

[0036] Step 1 - Data Preparation:

[0037] Prepare fixed cost parameters such as initial oil saturation of the target block, operating and drilling costs, surface construction investment, and fracturing costs;

[0038] Step 2 - Calculate the geological reserves per unit area and thickness:

[0039] Calculate the geological reserves per unit area and unit thickness based on the original oil saturation;

[0040]

[0041] Where: N p is geological reserves; S A is the unit area, i.e. 1km 2 ; h is the unit thickness, i.e. 1m; is the porosity; S oi is the original oil saturation; ρ o is the density of crude oil.

[0042] Step 3-Calculate the oil production per unit thickness of a single well:

[0043] According to different well spacing, calculate the number of wells per unit area and the controlled geological reserves of a single well per unit thickness. Predict water drive recovery rate based on reservoir engineering methods, and then obtain the oil production per unit thickness of a single well based on enhanced recovery;

[0044] n=S A / S well

[0045] N w =N P / n

[0046] N pj =ηN w

[0047] Where: Swell is the single well control area; N w is the controlled geological reserves per unit thickness of a single well; n is the number of wells per unit area, N pj is the oil production per unit thickness of a single well, and η is the recovery factor.

[0048] Step 4- Calculate fixed and operating costs:

[0049] According to the oilfield economic evaluation parameters, the fixed investment cost P of a single well is calculated respectively. g and operating cost P c (C P );

[0050] Step 5 - Calculate the total cost:

[0051] In order to ensure that the calculated combined thickness limit can ensure good economic benefits, the internal rate of return is introduced to calculate the total cost:

[0052]

[0053] Where: P a is the total cost; P c (C P ) is the operating cost; R is the loan interest rate; C is the internal rate of return; t is the development evaluation period; j is the jth year in the evaluation period.

[0054] Step 6 - Calculate crude oil revenue using the segmentation method:

[0055]

[0056] Where: R s is sales revenue, q o is the initial daily oil production of the new well, γ is the annual production rate, C r is the crude oil commodity rate; P o is the crude oil price; N 1 N is the last production period; 2 It is the stable production period; N 3 is the decreasing period; C is the internal rate of return; s 0 is the rate of increase in output; D 0 is the natural decline rate; t is the evaluation period; P s (C P ) are various taxes.

[0057] Step 7-Draw the thickness limit chart of the layer combination:

[0058] A trial calculation method is used to calculate the oil production of different layer combination thicknesses, and then the operating cost, total cost and crude oil sales revenue are calculated; the cumulative oil production of a single well when the crude oil sales revenue and the total cost are equal is the cumulative oil production limit of the single well, and the combination thickness at this time is the layer combination thickness limit; according to the above method, the layer combination thickness limits at different enhanced oil recovery factors, different well spacings and different oil prices are obtained, and the layer combination thickness limit chart is drawn.

[0059] Figure 1 It is the process of drawing the thickness limit chart of chemical flooding layer combination. According to the crude oil saturation and well spacing parameters, the controlled reserves per unit thickness of a single well are determined, and the oil production per unit thickness is obtained by combining the recovery factor. Calculate different combination thicknesses. When the oil production of the combination thickness makes the total cost and income equal, it is the combination thickness limit;

[0060] Example

[0061] The implementation process of the method of the present invention is described below by taking a block of Daqing Oilfield as an example.

[0062] Step 1-Prepare fixed cost parameters such as the original oil saturation of the target block, operating costs and drilling costs, ground construction investment, and fracturing costs. The original oil saturation of the block is 0.65, the average porosity is 0.22, and the crude oil density is 0.86g / cm 3 For other parameters, refer to the economic evaluation standards formulated by Daqing Oilfield.

[0063] Step 2 - Calculate the geological reserves per unit area and thickness:

[0064] The geological reserves per unit thickness per unit area are calculated according to the following formula, which is the reserve abundance:

[0065]

[0066] The calculated geological reserves per unit thickness per unit area of ​​this block are 12.30×10 4 t / km 2 .

[0067] Step 3-Calculate the oil production per unit thickness of a single well:

[0068] Under the condition of 125m well spacing, there are 64 oil and water wells per square kilometer, and the calculated controlled reserves per unit thickness of a single well are 1922t. When the recovery factor is increased by 10 percentage points, the oil production per unit thickness of a single well is 1153.2t.

[0069] n=S A / S well

[0070] N w =N P / n

[0071] N pj =ηN w

[0072] Step 4- Calculate fixed and operating costs:

[0073] Based on the economic parameters of the block, the fixed investment is calculated to be 184 million yuan. The operating cost varies with oil production and is not a constant. It is determined to be 359 million yuan after trial calculation in step 7.

[0074] Step 5 - Calculate the total cost:

[0075] In order to ensure that the calculated combined thickness limit can ensure good economic benefits, an internal rate of return of 6% is introduced, and the total calculated

[0076] Step 6 - Calculate the crude oil sales revenue at different oil prices using the segmentation method:

[0077] The segmented method is used to calculate the crude oil sales revenue at different oil prices. After the trial calculation in step 7, it is 598 million yuan.

[0078]

[0079] Step 7-Draw the thickness limit chart of the layer combination:

[0080] A trial calculation method is used to calculate the thickness of different strata combinations. When the sales revenue and total cost are equal, the cumulative oil production of a single well is the cumulative oil production limit of the single well, and the combination thickness at this time is the strata combination thickness limit. The strata combination thickness limit when the oil price is 70 US dollars per barrel, the well spacing is 125m, and the recovery factor is increased by 10% is 7.8m. According to the above steps, the strata combination thickness under different oil prices, different well spacings, and different chemical drive to increase recovery conditions is calculated, and the strata combination thickness chart is drawn. The strata combination thickness limit chart under the conditions of 125m well spacing and 10% chemical drive to increase recovery factor at different oil prices in this block is shown in Figure 2 Based on the combined thickness limit chart, the combined thickness limits of chemical flooding layers in different types of blocks, different oil prices, different enhanced oil recovery factors, and different well spacings can be quickly and accurately determined.

Claims

1. A method for drawing a chemical flooding layer combination thickness limit chart, characterized by: The steps include: Step 1: Data preparation, including the original oil saturation of the target block and cost parameters such as operating cost, drilling cost, surface construction investment and fracturing cost; Step 2: Apply the original oil saturation of the block to calculate the geological reserves per unit area and unit thickness, that is, the reserve abundance; The formula for calculating reserve abundance is: Where: N p is the geological reserves per unit area and unit thickness; S A is the unit area, i.e. 1km 2 ; h is the unit thickness, i.e. 1m; is the porosity; S oi is the original oil saturation; ρ o is the density of crude oil. Step 3: According to different well spacings, apply the definition of well pattern density to calculate the number of wells per unit area and the controlled geological reserves per unit thickness of a single well; The calculation formula of controlled geological reserves per unit thickness of a single well is: n=S A / S well N w =N P / n N pj =ηN w Where: S well is the single well control area; N w is the controlled geological reserves per unit thickness of a single well; n is the number of wells per unit area, N pj is the oil production per unit thickness of a single well, and η is the recovery factor. Step 4: Calculate fixed costs and operating costs, where operating costs are a function of oil production and are determined by trial calculation in step 7; Step 5: Calculate the total cost, of which the operating cost will be determined after the trial calculation in step 7; Step 6: Calculate the crude oil sales revenue at different oil prices using the segmentation method, and the oil production will be determined after the trial calculation in step 7; Step 7: Use the trial calculation method to calculate the oil production of different layer combination thicknesses, and then calculate the operating cost, total cost and crude oil sales revenue; when the crude oil sales revenue and total cost are equal, the single well cumulative oil production limit is the single well cumulative oil production limit, and the combination thickness at this time is the layer combination thickness limit; according to the above method, the layer combination thickness limits at different enhanced oil recovery factors, different well spacings and different oil prices are obtained, and the layer combination thickness limit chart is drawn.

2. A method for drawing a chemical flooding layer combination thickness limit chart according to claim 1, characterized in that: The specific method of step 4 is: according to the oilfield economic evaluation parameters, calculate the fixed investment cost P of a single well respectively. g and operating cost P c ; Among them, the operating cost P g It is a function of oil production and is determined by trial calculation in step 7.

3. A method for drawing a chemical flooding layer combination thickness limit chart according to claim 1, characterized in that: The specific method of step 5 is: in order to ensure that the calculated combined thickness limit can ensure good economic benefits, the internal rate of return is introduced to calculate the total cost: Where: P a is the total cost; P c (C P ) is the operating cost; C is the internal rate of return; t is the time.

4. The method for drawing a chemical flooding layer combination thickness limit chart according to claim 1, characterized in that: The specific method of step 6 is: calculate the crude oil sales revenue at different oil prices: Where: R s is sales revenue, q o is the initial daily oil production of the new well, γ is the annual production rate, C r is the crude oil commodity rate; P o is the crude oil price; N1 is the production period; N2 is the stable production period; N3 is the decline period; C is the internal rate of return; s0 is the production increase rate; D0 is the natural decline rate; t is the evaluation period; P s (C P ) are various taxes.

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