Evaluation method for commercial oil and gas flow criteria of continental shale oil reservoir reserves

Abstract

The application discloses a method for evaluating commercial oil and gas flow standard of continental shale oil reservoir, collects data in current commercial oil and gas flow standard parameter value table, collects representative well data in a block, calculates single-well minimum cumulative oil production, single-well minimum cumulative oil production per 100-meter horizontal well section, single-well minimum initial stable oil production and single-well minimum economic effective thickness according to commercial oil and gas flow standard parameters and well data, draws commercial oil and gas flow standard query chart under different well depths and prices of an oilfield, and evaluates commercial oil and gas flow of different reservoirs according to the commercial oil and gas flow standard query chart under different well depths and prices of the oilfield and the single-well minimum economic effective thickness. The application revises calculation parameters and calculation formulae according to actual development practice of continental shale oil reservoirs. Since the continental shale oil has the characteristics of "vertical well controlling reservoir and horizontal well increasing production", the evaluation standard of the continental shale oil reservoir is re-determined, and the application has wide economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of petroleum geological exploration and development technology, specifically involving a standard evaluation method for commercial oil and gas flow in continental shale oil reservoirs. Background Technology

[0002] 1. Traditional standard evaluation methods

[0003] Traditional commercial oil and gas flow standard evaluation methods for conventional oil reservoir reserves simply calculate the costs incurred during the development of conventional oil and gas reservoirs and then evaluate whether they have commercial development value.

[0004] 2. Problems with traditional standard evaluation methods

[0005] Compared to conventional oil reservoir development methods, continental shale oil reservoirs have poorer reservoir properties, greater seepage resistance, and smaller drainage areas. Conventional fracturing of cluster wells results in low single-well production, and only horizontal wells combined with high-displacement volumetric fracturing technology can achieve effective development. This approach is costly and yields low returns, making it significantly different from conventional oil and gas reservoirs. If evaluated according to the commercial oil and gas flow standards of conventional oil and gas reservoirs, most continental shale oil and gas reservoirs cannot meet commercial development value. Therefore, the original evaluation methods are no longer applicable to continental shale oil reservoirs. Summary of the Invention

[0006] The purpose of this invention is to provide a standard evaluation method for commercial oil and gas flow in continental shale oil reservoirs, which solves the problem that in the prior art, when evaluated according to the standard for commercial oil and gas flow in conventional oil and gas reservoirs, most continental shale oil and gas reservoirs cannot meet the commercial development value.

[0007] The technical solution adopted in this invention is: a standard evaluation method for commercial oil and gas flow in continental shale oil reservoirs, and the specific operation steps are as follows:

[0008] Step 1: Collect data from the current commercial oil and gas flow standard parameter value table;

[0009] Step 2: Collect representative well data from the block;

[0010] Step 3: Based on the commercial oil and gas flow standard parameters collected in Step 1 and the well data collected in Step 2, calculate the minimum cumulative oil production of a single well, the minimum cumulative oil production of a single well in a 100-meter horizontal well section, the minimum initial stable oil production of a single well, and the minimum economically effective thickness of a single well.

[0011] Step 4: Based on the calculation results of Step 3, draw a standard query chart of commercial oil and gas flow under different well depths and prices in the oil field;

[0012] Step 5: Based on the commercial oil and gas flow standard query chart and the minimum economically effective thickness of a single well under different well depths and prices in the oilfield, evaluate the commercial oil and gas flow of different reservoirs.

[0013] The invention is further characterized in that,

[0014] Step 3: Calculate the minimum cumulative oil production per well (EUR). mino The specific methods are as follows:

[0015]

[0016] Among them, R g It is the natural gas commodity rate; R o It is the crude oil commodity rate; P g It is the selling price of natural gas; P o It is the selling price of crude oil; C d It is the investment in the unit's development well project; C ab It is the cost of abandoning a single well; C fo It is the fixed operating cost of a single well oil well; C vo T is the variable operating cost per unit of oil; T is the lifespan of a single well; T axg It is a gas tax; T axo H is oil tax; H is average drilling footage; I is oil tax. c It is the necessary surface engineering investment for a single well; GOR is the gas-oil ratio.

[0017] Step 3: Calculate the minimum cumulative oil production (EUR) per well in the 100-meter horizontal well section. Le The method is as follows:

[0018]

[0019] Where L is the length of the horizontal well section.

[0020] Step 3: Minimum initial stable oil production q for a single well eio The calculation method is as follows:

[0021]

[0022] Where, d o is the annual decline rate of oil production; Da is the number of production days per well per year; n is the stable production period of a single well.

[0023] Step 3: The calculation method for the minimum economically effective thickness of a single well is as follows:

[0024] Based on the lowest cumulative oil production per well (EUR) mino Based on the recovery rate and controlled geological reserves of a single well, the following formula is established for calculating the minimum economically effective thickness of a single well:

[0025]

[0026] Where: h eo —Minimum economically effective thickness for a single well;

[0027] EUR mino —Minimum cumulative oil production per well;

[0028] B oi —Original crude oil volume coefficient;

[0029] E or —Economic recovery rate of oil;

[0030] ρ o —Surface crude oil density;

[0031] A o —Single well controls the oil drainage area;

[0032] φ—Effective porosity;

[0033] S oi —Original oil saturation.

[0034] The specific method for drawing the standard query chart of commercial oil and gas flow under different well depths and prices in oilfields, as described in step 4, is as follows:

[0035] Calculate the minimum initial stable oil production of a single well at each depth under different oil prices, project the calculated data onto the chart as the Y-axis, connect the projection points of different oil prices to form a line, and draw the lower limit of the minimum initial stable oil production of a single well under different oil prices.

[0036] Step 5 evaluates whether commercial oil and gas flow is possible using the following method:

[0037] Step 5.1: First, calculate the minimum initial stable oil production of a single well based on the well depth, project it onto the commercial oil and gas flow standard query chart for different well depths and prices, and check whether it is above the current oil price line in conjunction with the current oil price.

[0038] Step 5.2: Collect the minimum economically effective thickness of a single well and the initial stable daily oil production, draw a graph showing the relationship between the initial stable daily oil production and the minimum economically effective thickness of a single well, and obtain the minimum effective reservoir thickness in the region; combine the minimum effective reservoir thickness in the region with the thickness of the reservoir to be evaluated. If the thickness is greater than the minimum effective thickness in the region, it meets the commercial oil and gas flow standard requirements.

[0039] If the reservoir meets the requirements of steps 5.1 and 5.2, then the reservoir has commercial oil and gas flow standards.

[0040] The beneficial effects of this invention are as follows: This invention, combined with actual development practices of continental shale oil reservoirs, has made necessary revisions to the calculation parameters and formulas. The standard for commercial oil and gas flow in horizontal wells is 5.10 t / d. Since continental shale oil has the characteristic of "vertical wells controlling reservoirs, horizontal wells increasing production," it is necessary to determine the standard for commercial oil and gas flow in vertical wells. In the Qingcheng Oilfield, the average reservoir burial depth of vertical wells is 1720 m, corresponding to a commercial oil and gas flow standard of 1.0 t / d, which is greater than the reserve calculation starting standard of 1.0 m for the same oil (gas) reservoir burial depth in the People's Republic of China Geological and Mineral Resources Industry Standard DZ / T0217-2020 "Specification for Estimation of Petroleum and Natural Gas Reserves". 3 / d (approximately 0.83t / d). Attached Figure Description

[0041] Figure 1 This is a flowchart of the commercial oil and gas flow standard evaluation method for continental shale oil reservoir reserves of the present invention;

[0042] Figure 2 This is a standard query chart of commercial oil and gas flow under different well depths and prices in this embodiment of the invention;

[0043] Figure 3 This is a graph showing the relationship between the initial stable production of a horizontal well and the minimum economically effective thickness of a single well in an embodiment of the present invention. Detailed Implementation

[0044] Example 1

[0045] The commercial hydrocarbon flow standard evaluation method for continental shale oil reservoir reserves of the present invention is implemented according to the following steps:

[0046] A. Collect data from the current commercial oil and gas flow standard parameter value table;

[0047] B. Collect representative well data from the block;

[0048] C. Based on the standard parameters of commercial oil and gas flow collected in step 1 and the well data collected in step 2, calculate the minimum cumulative oil production of a single well, the minimum cumulative oil production of a single well in a 100-meter horizontal well section, the minimum initial stable oil production of a single well, and the minimum economically effective thickness of a single well.

[0049] D. Based on the calculation results in step 3, draw a standard query chart of commercial oil and gas flow under different well depths and prices in the oil field;

[0050] E. Calculate the minimum initial stable oil production and minimum economically effective thickness of a single well in the block to be evaluated. Based on the commercial oil and gas flow standards query charts and minimum economically effective thickness of a single well under different well depths and prices in the oilfield, conduct a commercial oil and gas flow assessment of the reservoir.

[0051] According to the relevant provisions of the "Detailed Rules for the Evaluation and Management of Economically Recoverable Reserves of Oil and Gas (Trial Implementation)" (Oil Exploration

[2018] No. 312), Articles 12 and 13 stipulate that the economic evaluation of single-well reserves is based on future costs, without considering discounting, and calculates the lower limit standard according to the break-even principle and the development status. Generally, the economic evaluation of single-well reserves of developed reserves mainly recovers operating costs and related taxes and fees, while the economic evaluation of single-well reserves of undeveloped reserves also needs to consider the drilling and completion investment of single well and necessary surface investment.

[0052] 8.1) Standard Calculation Method for Commercial Oil and Gas Flow

[0053] Minimum initial stable production per well in undeveloped reserves (q) eio Based on the break-even principle and the principle that the drilling and completion investment of the development well in this exploration area, the necessary surface engineering investment, operating costs, disposal costs, and related taxes and fees can be recovered within the life of a single well, the following calculation formula is established: Minimum cumulative oil production per well (EUR) mino yes:

[0054]

[0055] Minimum cumulative oil production per well in 100-meter horizontal section (EUR) Le for:

[0056]

[0057] Taking into account the declining production during the oil well production period, the formula for calculating the minimum initial stable production of a single well is as follows:

[0058]

[0059] In the formula:

[0060] EUR mino —Minimum cumulative oil production per well, 10 4 t;

[0061] EUR Le —100-meter horizontal well section EUR, 10 4 t / 10 2 m;

[0062] q eio —Minimum initial stable oil production per well, t / d;

[0063] C d —Investment per unit of development well project, ¥ / m;

[0064] H—average drilling footage, m;

[0065] L—Length of the horizontal well section, 10 2 m;

[0066] C ab —Cost of abandoning a single well, 10 4 ¥;

[0067] I c —Necessary surface engineering investment for a single well, 10 4 ¥;

[0068] C fo —Fixed operating costs for a single well oil well, 10 4 ¥ / a;

[0069] C vo —Variable operating cost per unit of oil, ¥ / t;

[0070] R o - Crude oil commodity rate, f;

[0071] R g - Natural gas commodity rate, f;

[0072] P o —Crude oil selling price, ¥ / t;

[0073] P g —Natural gas sales price, ¥ / 10 3 m 3 ;

[0074] T axo —Oil tax, ¥ / ton;

[0075] T axg —Gas tax, ¥10 3 m 3 ;

[0076] GOR—Gas-to-oil ratio, 10 3 m 3 / t;

[0077] T—Lifespan of a single well, a;

[0078] n—single-well stable production period, a;

[0079] d o —Annual decline rate of oil production, f;

[0080] Da—Number of production days per year for a single well, d;

[0081] Table 1 Standard Parameter Values ​​for Commercial Oil and Gas Flow

[0082]

[0083]

[0084] The average designed completed well depth of the horizontal wells in the newly predicted reserve blocks of the oilfield is 3955 meters (including a horizontal section of 1750 meters). Substituting the parameters (as shown in Table 1) into the above formulas (1), (2), and (3), the minimum cumulative oil production of a single horizontal well in the Qingcheng Oilfield is calculated to be 1.124 × 10⁻⁶. 4 The minimum cumulative oil production per 100-meter horizontal well section is 642 tons, and the commercial oil and gas flow standard for horizontal wells is determined to be 5.10 tons / day. Since continental shale oil has the characteristic of "vertical wells controlling reservoirs and horizontal wells increasing production," it is necessary to determine the commercial oil and gas flow standard for vertical wells. The average reservoir burial depth of vertical wells in the Qingcheng Oilfield is 1720 meters, corresponding to a commercial oil and gas flow standard of 1.0 tons / day, which is greater than the reserve calculation starting standard of 1.0 meters for the same oil (gas) reservoir burial depth in the People's Republic of China Geological and Mineral Resources Industry Standard DZ / T0217-2020 "Specification for Estimation of Petroleum and Natural Gas Reserves". 3 / d (approximately 0.83t / d).

[0085] Based on the above formulas (1) and (3), a standard query chart for commercial oil and gas flow at different well depths and prices in Qingcheng Oilfield can be drawn (e.g., Figure 2 (as shown), so that the corresponding commercial oil and gas flow standards can be quickly found when applying them.

[0086] 8.2) Evaluation method for minimum economically effective thickness of a single well

[0087] Based on the single-well EUR, recovery rate, and controlled geological reserves of a single well, the following formula is established for calculating the minimum economically effective thickness of a single well:

[0088]

[0089] In the formula:

[0090] h eo —Minimum economically effective thickness of a single well, in meters;

[0091] EUR mino —Minimum cumulative oil production per well, 10 4 t;

[0092] B oi —Original crude oil volume coefficient, dimensionless;

[0093] E or —Economic recovery rate of oil, f;

[0094] ρ o —Surface crude oil density, t / m³ 3 ;

[0095] A o —Single well controlled oil drainage area, km 2 ;

[0096] φ—effective porosity, f;

[0097] S oi —Original oil saturation, f.

[0098] Substituting the parameters from Table 2 into formula (4), the minimum economically effective thickness of a single well in the oilfield can be calculated to be 4.0 m. To verify the rationality of the results, the relationship between the initial stable production of horizontal wells and the thickness of the oil layer within the oil-bearing area was statistically analyzed (e.g., ...). Figure 3 As shown in the figure, the trend line indicates that with an effective thickness of 4.0m, the initial stable production of a horizontal well exceeds the commercial oil and gas flow standard of 5.10t / d. Actual production data confirms the rationality of 4.0m as the minimum economically effective thickness for a single well.

[0099] Table 2 Calculation Results of Minimum Economically Effective Thickness for Single Wells

[0100]

[0101] Example 2

[0102] Based on the basic oilfield data for Qingcheng Oilfield in 2020 obtained using the commercial oil and gas flow standard evaluation method for continental shale oil reservoir reserves according to this invention (as shown in Table 3), the minimum economically effective thickness for a single well in the oilfield can be calculated to be 5.0 m. The trend line in the figure shows that when the effective thickness is 5.0 m, the initial stable production of horizontal wells exceeds the commercial oil and gas flow standard of 5.10 t / d. Actual production data confirms the rationality of using 5.0 m as the minimum economically effective thickness for a single well.

[0103] Table 3. Calculation Results of Minimum Economically Effective Thickness for Single Wells

[0104]

[0105] Example 3

[0106] Based on the basic data of Qingcheng Oilfield obtained using the commercial oil and gas flow standard evaluation method for continental shale oil reservoir reserves according to this invention (as shown in Table 4), the minimum economically effective thickness for a single well in the oilfield is calculated to be 4.0 m. The trend line in the figure shows that when the effective thickness is 4.0 m, the initial stable production of horizontal wells exceeds the commercial oil and gas flow standard of 5.10 t / d. Actual production data confirms the rationality of 4.0 m as the minimum economically effective thickness for a single well.

[0107] Table 4. Calculation Results of Minimum Economically Effective Thickness for Single Wells

[0108]

[0109] Example 4

[0110] Based on the basic data of Qingcheng Oilfield obtained using the commercial oil and gas flow standard evaluation method for continental shale oil reservoir reserves according to this invention (as shown in Table 5), the minimum economically effective thickness for a single well in the oilfield is calculated to be 4.0 m. The trend line in the figure shows that when the effective thickness is 4.0 m, the initial stable production of horizontal wells exceeds the commercial oil and gas flow standard of 5.10 t / d. Actual production data confirms the rationality of 4.0 m as the minimum economically effective thickness for a single well.

[0111] Table 5. Calculation Results of Minimum Economically Effective Thickness for Single Wells

[0112]

Claims

1. A standard evaluation method for commercial oil and gas flow in continental shale oil reservoirs, characterized in that, The specific steps are as follows: Step 1: Collect data from the current commercial oil and gas flow standard parameter value table; Step 2: Collect representative well data from the block; Step 3: Based on the commercial oil and gas flow standard parameters collected in Step 1 and the well data collected in Step 2, calculate the minimum cumulative oil production of a single well, the minimum cumulative oil production of a single well in a 100-meter horizontal well section, the minimum initial stable oil production of a single well, and the minimum economically effective thickness of a single well. Step 4: Based on the calculation results of Step 3, draw a standard query chart of commercial oil and gas flow under different well depths and prices in the oil field; Step 5: Based on the commercial oil and gas flow standard query chart and the minimum economically effective thickness of a single well under different well depths and prices in the oilfield, evaluate the commercial oil and gas flow of different reservoirs.

2. The commercial hydrocarbon flow standard evaluation method for continental shale oil reservoir reserves according to claim 1, characterized in that, Step 3: Calculate the minimum cumulative oil production per well (EUR). mino The specific methods are as follows: Among them, R g It is the natural gas commodity rate; R o It is the crude oil commodity rate; P g It is the selling price of natural gas; P o It is the selling price of crude oil; C d It is the investment in the unit's development well project; C ab It is the cost of abandoning a single well; C fo It is the fixed operating cost of a single well oil well; C vo T is the variable operating cost per unit of oil; T is the lifespan of a single well; T axg It is a gas tax; T axo H is oil tax; H is average drilling footage; I is oil tax. c It is the necessary surface engineering investment for a single well; GOR is the gas-oil ratio.

3. The commercial hydrocarbon flow standard evaluation method for continental shale oil reservoir reserves according to claim 2, characterized in that, Step 3: Calculate the minimum cumulative oil production (EUR) per well in the 100-meter horizontal well section. Le The method is as follows: Where L is the length of the horizontal well section.

4. The commercial hydrocarbon flow standard evaluation method for continental shale oil reservoir reserves according to claim 2, characterized in that, The minimum initial stable oil production q of a single well as described in step 3 eio The calculation method is as follows: Where, d o is the annual decline rate of oil production; Da is the number of production days per well per year; n is the stable production period of a single well.

5. The commercial hydrocarbon flow standard evaluation method for continental shale oil reservoir reserves according to claim 1, characterized in that, The method for calculating the minimum economically effective thickness of a single well in step 3 is as follows: Based on the lowest cumulative oil production per well (EUR) mino Based on the recovery rate and controlled geological reserves of a single well, the following formula is established for calculating the minimum economically effective thickness of a single well: Where: h eo —Minimum economically effective thickness for a single well; EUR mino —Minimum cumulative oil production per well; B oi —Original crude oil volume coefficient; E or —Economic recovery rate of oil; ρ o —Surface crude oil density; A o —Single well controls the oil drainage area; φ—Effective porosity; S oi —Original oil saturation.

6. The commercial hydrocarbon flow standard evaluation method for continental shale oil reservoir reserves according to claim 1, characterized in that, The specific method for drawing the standard query chart of commercial oil and gas flow under different well depths and prices in oilfields, as described in step 4, is as follows: Calculate the minimum initial stable oil production of a single well at each depth under different oil prices, project the calculated data onto the chart as the Y-axis, connect the projection points of different oil prices to form a line, and draw the lower limit of the minimum initial stable oil production of a single well under different oil prices.

7. The commercial oil and gas flow standard evaluation method for continental shale oil reservoir reserves according to claim 1, characterized in that, Step 5 evaluates whether commercial oil and gas flow is possible using the following method: Step 5.1: First, calculate the minimum initial stable oil production of a single well based on the well depth, project it onto the commercial oil and gas flow standard query chart for different well depths and prices, and check whether it is above the current oil price line in conjunction with the current oil price. Step 5.2: Collect the minimum economically effective thickness of a single well and the initial stable daily oil production, draw a graph showing the relationship between the initial stable daily oil production and the minimum economically effective thickness of a single well, and obtain the minimum effective reservoir thickness in the region; combine the minimum effective reservoir thickness in the region with the thickness of the reservoir to be evaluated. If the thickness is greater than the minimum effective thickness in the region, it meets the commercial oil and gas flow standard requirements. If the reservoir meets the requirements of steps 5.1 and 5.2, then the reservoir has commercial oil and gas flow standards.

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