Method and model for predicting economic recoverable reserves in later stage of huff and puff of extra-heavy oil reservoir

Abstract

The application discloses a method and a model for predicting economic recoverable reserves in a late huff and puff stage of a special heavy oil reservoir, and obtains economic recoverable reserves of a target block based on an economic limit annual oil production, and obtains a recoverable reserve calculation model based on a relationship between a logarithm of a cumulative oil production value of the target block and an annual oil production value / cumulative oil production value. For the special heavy oil reservoir, the economic recoverable reserves determined by the application are more in line with oilfield development actualities than an injection-production relationship method.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, and in particular to a method and model for predicting the economically recoverable reserves in the later stages of huff and puff of extra-heavy oil reservoirs. Background Technology

[0002] In the process of oilfield development, scientifically and rationally predicting the recoverable reserves of oil reservoirs is an important basis for evaluating the development effect of oilfields, conducting dynamic analysis of oilfields, formulating oilfield development and adjustment plans, and determining the direction of potential tapping and management.

[0003] Currently, the method for calculating the economically recoverable reserves of heavy oil reservoirs developed through huff and puff is the injection-production relationship method. This method was proposed in the early 1990s, when the heavy oil being developed was ordinary heavy oil, a single type of oil. Due to limitations in extraction technology, the limiting oil-to-gas ratio for huff and puff development was 0.25. Extra-heavy oil was put into development in the mid-1990s, and its development pattern differs from that of ordinary heavy oil. With the continuous advancement of heavy oil extraction technology in later periods, the limiting oil-to-gas ratio has decreased, and the injection-production relationship method has resulted in an underestimation of the economically recoverable reserves of extra-heavy oil, which does not reflect the actual development of extra-heavy oil reservoirs.

[0004] Therefore, existing technologies still need improvement. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a method and model for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs, thereby resolving the technical issue that existing injection-production relationship methods cannot meet the requirements for predicting recoverable reserves of extra-heavy oil.

[0006] On the one hand, the method for predicting the economically recoverable reserves in the later stage of huff and puff of an extra-heavy oil reservoir disclosed in the embodiments of the present invention obtains the economically recoverable reserves of the target block based on the economically limited annual oil production.

[0007] Furthermore, a recoverable reserves calculation model is established, and the economically limited annual oil production is substituted into the recoverable reserves calculation model to obtain the economically recoverable reserves of the target block.

[0008] Furthermore, the recoverable reserves calculation model is derived based on the logarithm of the cumulative oil production value of the target block and the relationship between the annual oil production value and the cumulative oil production value.

[0009] Furthermore, the establishment of a recoverable reserves calculation model includes:

[0010] A two-dimensional rectangular coordinate system is established, where the horizontal axis is the logarithm of the cumulative oil production value of the target block, and the vertical axis is the annual oil production value / cumulative oil production value of the target block. The relationship curve between the logarithm of the cumulative oil production value and the annual oil production value / cumulative oil production value of the target block is obtained by fitting, and it serves as a model for calculating recoverable reserves.

[0011] Furthermore, by substituting the economic limit annual oil production of the target block as the annual oil production value into the logarithm of the cumulative oil production value of the target block and the relationship curve between the annual oil production value and the cumulative oil production value, the corresponding cumulative oil production value is obtained, which is the economic recoverable reserve of the target block.

[0012] Furthermore, the relationship curve between the logarithm of the cumulative oil production value of the target block and the annual oil production value / cumulative oil production value is as follows:

[0013]

[0014] Among them, Q o N represents the annual oil production value. p To accumulate oil production value.

[0015] Furthermore, by substituting the economically limited annual oil production of the target block as the annual oil production value into the logarithm of the cumulative oil production value of the target block and the relationship curve between the annual oil production value and the cumulative oil production value, the cumulative oil production value obtained is the economically recoverable reserves.

[0016] Furthermore, the annual oil production value and the cumulative oil production value are obtained from the historical development data of the target block.

[0017] Furthermore, the economic limit annual oil production of the target block is calculated using the economic limit annual oil production calculation formula.

[0018] Furthermore, the economic limit annual oil production of the target block is related to the economic parameters of the target block's economic evaluation year.

[0019] Furthermore, the economic parameters for the target block's economic evaluation year include the price of oil excluding tax, fixed costs, variable costs per ton of oil, taxes and fees per ton of oil, and oil commodity rate.

[0020] Furthermore, the formula for calculating the economically optimal annual oil production is as follows:

[0021]

[0022] in,

[0023] Q L The economically limited annual oil production capacity,

[0024] P o This price is excluding tax.

[0025] C fo For fixed costs,

[0026] R represents the oil product yield.

[0027] T axo Taxes and fees per ton of oil,

[0028] C voThe variable cost per ton of oil.

[0029] Furthermore, including:

[0030] Step 1: Obtain historical development data for the target block, including annual oil production value Q. o Units: 10,000 tons, cumulative oil production value N p Unit: 10,000 tons;

[0031] Step 2: Obtain the economic parameters for the target block's economic evaluation year, including the pre-tax oil price P. o Unit: Yuan / ton, Fixed Cost C fo Unit: RMB 10,000 / year, variable cost per ton of oil C vo Unit: Yuan / ton, Taxes and Fees per Ton of Oil (T) axo Unit: Yuan / ton; Oil commodity rate R, unit: decimal;

[0032] Step 3, adopt the economic limit annual oil production Q L Calculation formula Calculate the economic limit annual oil production of the target block;

[0033] Step 4: Establish a two-dimensional rectangular coordinate system, where the horizontal axis is the logarithm of the cumulative oil production value, and the vertical axis is the annual oil production value / cumulative oil production value;

[0034] Step 5: Plot the logarithm of the cumulative oil production value and the ratio of annual oil production value to cumulative oil production value in a Cartesian coordinate system. A strong linear relationship exists between the logarithm of the cumulative oil production value and the ratio of annual oil production value to cumulative oil production value. Modeling this relationship, we obtain the following equation:

[0035]

[0036] Step 6: Substitute the calculated economic limit annual oil production as the annual oil production value into the formula to calculate the corresponding cumulative oil production value N. p That is, the economically recoverable reserves N of the target block. J ;

[0037] Step 7: Conduct a rationality analysis of economically recoverable reserves.

[0038] On the other hand, this invention also discloses a recoverable reserves calculation model for predicting economically recoverable reserves in the later stages of huff and puff of extra-heavy oil reservoirs, which is based on the relationship between the logarithm of the cumulative oil production value of the target block and the annual oil production value / cumulative oil production value.

[0039] Furthermore, a two-dimensional rectangular coordinate system is established, where the horizontal axis is the logarithm of the cumulative oil production value of the target block, and the vertical axis is the annual oil production value / cumulative oil production value of the target block. The relationship curve between the logarithm of the cumulative oil production value and the annual oil production value / cumulative oil production value of the target block is obtained by fitting, and used as a recoverable reserve calculation model.

[0040] Furthermore, the relationship curve between the logarithm of the cumulative oil production value of the target block and the annual oil production value / cumulative oil production value is as follows:

[0041]

[0042] Among them, Q o N represents the annual oil production value. p To accumulate oil production value.

[0043] Furthermore, by substituting the economically limited annual oil production of the target block as the annual oil production value into the logarithm of the cumulative oil production value of the target block and the relationship curve between the annual oil production value and the cumulative oil production value, the cumulative oil production value obtained is the economically recoverable reserves.

[0044] Furthermore, the annual oil production value and the cumulative oil production value are obtained from the historical development data of the target block.

[0045] Furthermore, the economic limit annual oil production of the target block is related to the economic parameters of the target block's economic evaluation year.

[0046] By adopting the above technical solution, the present invention has at least the following beneficial effects:

[0047] This invention provides a method and model for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs. For extra-heavy oil reservoirs, the economically recoverable reserves determined by this invention are more consistent with actual oilfield development than the injection-production relationship method. For example, the annual oil production of the X extra-heavy oil calibration unit is 102,800 tons, and the cumulative oil production is 4,927,200 tons. Using the model of this invention, the economically recoverable reserves are calculated to be 5,425,500 tons, with a reserve-production ratio of 4.9. The result calculated using the injection-production relationship method is 5,006,400 tons, with a reserve-production ratio of 0.8. The result calculated using the model of this invention matches current development indicators and is more consistent with actual development. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1This diagram illustrates the establishment of an economically recoverable reserve calculation model for the later stages of huff and puff in an extra-heavy oil reservoir, as disclosed in an embodiment of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0051] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0052] A method for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs, where the viscosity of the degassed crude oil at the reservoir temperature is 10,000–50,000 mPa·s and the density is >0.95 g / cm³. 3 The establishment of a method for predicting economically recoverable reserves in the later stages of huff and puff in this extra-heavy oil reservoir includes:

[0053] Step 1: Obtain historical development data for the target block, including annual oil production value (Q). o Unit: 10,000 tons, cumulative oil production value (N) p Unit: 10,000 tons;

[0054] Step 2: Obtain the economic parameters for the target block's economic evaluation year, including the pre-tax oil price (P). o Unit: Yuan / ton, Fixed Costs (C) fo Unit: RMB 10,000 / year, variable cost per ton of oil (C) vo Unit: Yuan / ton, Oil tax and fees per ton (T) axo Unit: Yuan / ton; Oil Commodity Rate (R) Unit: Decimal;

[0055] Step 3, adopt the economic limit annual oil production (Q) L ) Calculation formula Calculate the economic limit annual oil production of the target block;

[0056] Step 4: Establish a two-dimensional rectangular coordinate system, where the horizontal axis is the logarithm of the cumulative oil production value, and the vertical axis is the annual oil production value / cumulative oil production value;

[0057] Step 5: Plot the logarithm of the cumulative oil production value and the annual oil production value / cumulative oil production value of the target block in a rectangular coordinate system. There is a good linear relationship between the logarithm of the cumulative oil production value and the annual oil production value / cumulative oil production value. Modeling this pattern, we can obtain the following relationship (1):

[0058]

[0059] Step 6: Substitute the calculated economic limit annual oil production into equation (1) to calculate the corresponding cumulative oil production value N. p That is, the economically recoverable reserves N of the evaluation block. J ;

[0060] Step 7: Conduct a rationality analysis of economically recoverable reserves.

[0061] The objective of this invention can also be achieved through the following technical measures:

[0062] In step 1, historical development data of the target block is obtained, including annual oil production value and cumulative oil production value;

[0063] In step 2, the economic parameters for the target block's economic evaluation year are obtained, including the oil price excluding tax, fixed costs, variable costs per ton of oil, taxes and fees per ton of oil, and oil commodity rate.

[0064] In step 3, the economic limit annual oil production of the target block is calculated using the economic limit annual oil production calculation formula;

[0065] In step 4, a two-dimensional rectangular coordinate system is established, where the horizontal axis is the logarithm of the cumulative oil production value and the vertical axis is the annual oil production value / cumulative oil production value.

[0066] In step 5, the logarithm of the cumulative oil production value and the ratio of annual oil production value to cumulative oil production value of the target block are projected into a rectangular coordinate system. By selecting a clear straight line segment for fitting, the following relationship can be obtained:

[0067]

[0068] In step 6, the calculated economic limit annual oil production is substituted into equation (1) to calculate the corresponding cumulative oil production value N. p That is, the economically recoverable reserves N of the evaluation block. J ;

[0069] In step 7, a rationality analysis is conducted through the corresponding development indicators to truly and objectively reflect the actual development level of the reservoir.

[0070] Example 1

[0071] This invention defines the specific implementation process for establishing the economically recoverable reserves calculation model for X extra-heavy oil calibration units:

[0072] The first step is to obtain historical development data of the X heavy oil calibration unit, including annual oil production value (in 10,000 tons) and cumulative oil production value (in 10,000 tons), as shown in Table 1.

[0073] Table 1. Historical Development Data of Extra Heavy Oil Calibration Unit

[0074]

[0075] The second step is to obtain the economic parameters for the economic evaluation year of the X-type heavy oil calibration unit, including the oil price excluding tax of RMB 2,844 / ton, fixed costs of RMB 64.5816 million / year, variable costs per ton of oil of RMB 418.82 / ton, taxes and fees per ton of oil of RMB 174.06 / ton, and oil commodity rate of 1.

[0076] The third step is to use the economic limit annual oil production calculation formula. The economic limit for annual oil production of the X extra-heavy oil calibration unit is calculated to be 28,600 tons.

[0077] The fourth step is to establish a two-dimensional rectangular coordinate system, where the horizontal axis is the logarithm of the cumulative oil production value and the vertical axis is the annual oil production value / cumulative oil production value.

[0078] Fifth step, as Figure 1 As shown, the logarithm of the cumulative oil production value and the annual oil production value / cumulative oil production value of the X-type heavy oil calibration unit are projected into a rectangular coordinate system. A significant straight line segment from 2002 to 2015 is selected for fitting, yielding lnN. p With Q o / N p Relationship Q o / N p =1.1587-0.1832lnN p .

[0079] Step 6: Substitute the economic limit of 28,600 tons of oil production calculated in Step 3 into the relationship obtained in Step 5 to calculate the corresponding cumulative oil production value N. p That is, the economically recoverable reserves N of the X-type heavy oil calibration unit. J It was 5.4255 million tons.

[0080] Step 7: The annual oil production value of the X-type heavy oil calibration unit is 102,800 tons, and the cumulative oil production value is 4,927,200 tons. Using the model of this invention, the economically recoverable reserves are calculated to be 5,425,500 tons, with a reserve-to-production ratio of 4.9, which matches the current development indicators. The calculation results of the model of this invention are more in line with the actual development situation.

[0081] In summary, the method and model for predicting economically recoverable reserves in the later stages of huff and puff development of extra-heavy oil reservoirs disclosed in this invention fully utilize the strong linear relationship between the logarithm of cumulative oil production and the annual oil production / cumulative oil production in a rectangular coordinate system during the later stages of huff and puff development of extra-heavy oil reservoirs. This relationship is modeled into a formula, where the cumulative oil production N is the economically limit annual oil production. p That is, the economically recoverable reserves N of the evaluation block. J This method effectively solves the problem that existing injection-production relationship methods tend to underestimate the economically recoverable reserves of extra-heavy oil, failing to reflect the actual development of extra-heavy oil reservoirs.

[0082] It should be noted that the components or steps in the above embodiments can be interchanged, substituted, added, or deleted. Therefore, the combinations formed by these reasonable permutations and transformations should also fall within the protection scope of this invention, and the protection scope of this invention should not be limited to the above embodiments.

[0083] The above are exemplary embodiments disclosed in this invention. The order of the disclosed embodiments is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. However, it should be noted that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of this invention (including the claims) is limited to these examples. Various changes and modifications can be made without departing from the scope defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular.

[0084] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs, characterized in that, Establish a recoverable reserves calculation model and obtain the economically recoverable reserves of the target block based on the economically limit annual oil production. The establishment of a recoverable reserves calculation model includes: establishing a two-dimensional rectangular coordinate system, where the horizontal axis is the logarithm of the cumulative oil production value of the target block, and the vertical axis is the annual oil production value / cumulative oil production value of the target block. The relationship curve between the logarithm of the cumulative oil production value and the annual oil production value / cumulative oil production value of the target block is obtained by fitting, and used as the recoverable reserves calculation model. The economically recoverable reserves of a target block are obtained based on the economic limit annual oil production. This involves substituting the economic limit annual oil production of the target block as the annual oil production value into the logarithm of the cumulative oil production value of the target block and the relationship curve between the annual oil production value and the cumulative oil production value, and the corresponding cumulative oil production value is the economically recoverable reserves of the target block. The relationship curve between the logarithm of the cumulative oil production value and the annual oil production value / cumulative oil production value of the target block is as follows: Among them, Q o N represents the annual oil production value. p To accumulate oil production value.

2. The method for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs according to claim 1, characterized in that, The annual oil production value and the cumulative oil production value are obtained from the historical development data of the target block.

3. The method for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs according to claim 1, characterized in that, The economic limit annual oil production of the target block is calculated using the economic limit annual oil production calculation formula.

4. The method for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs according to claim 3, characterized in that, The economic limit annual oil production of the target block is related to the economic parameters of the target block's economic evaluation year.

5. The method for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs according to claim 1, characterized in that, The economic parameters for the target block's economic evaluation year include the price of oil excluding tax, fixed costs, variable costs per ton of oil, taxes and fees per ton of oil, and the oil commodity rate.

6. The method for predicting economically recoverable reserves in the later stages of huff and puff in extra-heavy oil reservoirs according to claim 3, characterized in that, The formula for calculating the economically optimal annual oil production is: in, The economically limited annual oil production capacity, This price is excluding tax. For fixed costs, For oil commodity rate, Taxes and fees per ton of oil, The variable cost per ton of oil.

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