CN105134191B - The evaluation method of fine and close oil well reserves - Google Patents
The evaluation method of fine and close oil well reserves Download PDFInfo
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- CN105134191B CN105134191B CN201510526436.9A CN201510526436A CN105134191B CN 105134191 B CN105134191 B CN 105134191B CN 201510526436 A CN201510526436 A CN 201510526436A CN 105134191 B CN105134191 B CN 105134191B
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Abstract
The invention discloses a kind of evaluation method of fine and close oil well reserves, it is related to oil-gas exploration and development technical field, mainly solves the problems, such as that fine and close oil well reserve forecasting precision is low.This method is classified to obtain the abundance of each fine and close oily oil well in fine and close oil wells at different levels using the geologic(al) factor in fine and close oil well region from the mining state of fine and close oil well to different fine and close oil wells, by calculating its abundance plane distribution so as to obtaining the economic coefficient of each fine and close oil well in fine and close oil wells at different levels, fine and close oil wells at different levels are divided into by the economic coefficient again different classes of, the reserves of the not lower fine and close oil well of all types are finally given on the basis of the abundance of fine and close oil well of all categories in the area and fine and close oil oil at different levels of the unique close oil well of all types.The evaluation method of fine and close oil well reserves effectively raises the precision to the prediction of fine and close oilreserves in the present invention.
Description
Technical Field
The invention relates to the technical field of oil-gas exploration and development, in particular to a method for evaluating the reserves of a compact oil well, which is used for evaluating the reserves of the compact oil well.
Background
The dense oil refers to the permeability of the matrix under the pressure of the reservoir, which is less than or equal to 0.1 x 10-3 mu m 2 The compact shale, the compact sandstone or the compact carbonate rock and the like. At present, the compact oil is still in the initial stage of exploration and is an important growth point of future oil yield, the global compact oil yield reaches 2 hundred million tons in 2014, and the recoverable and storable amount of the global compact oil technology can reach 300 to 400 hundred million tons according to the evaluation of domestic and foreign institutions. As the compact oil belongs to one of unconventional oil and gas resources, has the characteristics of large-scale continuous aggregation, source-in or near source accumulation, source-storage integration and the like, has great difference with the underground aggregation mode and development means of the conventional petroleum, and cannot be simply evaluated by using a conventional method. However, according to the progress and results of some compact oil reserves prediction studies which have been carried out at home and abroad, the conventional method for evaluating the compact oil reserves still adopts the conventional method for evaluating the oil and gas reserves, mainly a volumetric method, a similar ratio method and a probability method.
The volume method is a method for drawing the spatial distribution condition of underground compact oil in a region to be evaluated based on well logging and seismic data, calculating the volume of a compact oil layer and estimating the reserve volume of the compact oil through the porosity of the oil layer. The volumetric method is used for evaluating the reserve volume of compact oil based on a conventional oil-gas underground gathering mode, has certain applicability to a homogeneous thick-layer compact oil layer, but has strong heterogeneity to most compact oil layers, the transverse and longitudinal changes are quick, and the geological parameters of the compact oil layer can hardly be calibrated, so that the final evaluation result is extremely low in precision. The probability statistical method comprises the steps of utilizing the finally estimated recoverable reserves in a producing well, establishing a probability distribution diagram of the total recoverable reserves in the producing well, determining the number N of drilled wells in a region to be evaluated, obtaining the finally estimated recoverable reserves of single wells correspondingly on the probability distribution diagram of the total recoverable reserves in the producing well through Monte Carlo random simulation, selecting N times to obtain the finally estimated recoverable reserves of the N single wells, obtaining an average value, inputting the average value, repeating the process for 5000 to 10000 times to obtain 5000-10000 average values, making a new finally estimated recoverable reserves probability statistical distribution diagram according to the values, and obtaining the P1, P2 and P3 grades of reserves of non-drilled regions according to different probabilities. The probability statistics method is a method based on mathematical statistics to calculate the compact oil reserves, wherein the influence of geological factors is not considered, and the difference of the geological factors has great influence on the reserves of the oil and gas reservoirs in any region, in particular hydrocarbon source conditions capable of reflecting the oil production capacity and reservoir conditions capable of reflecting the reservoir capacity. Therefore, a probability statistical method of geological factors is neglected, and accurate compact oil reserves cannot be obtained. The analogy method is that a calibration area is established by utilizing geological conditions and development well characteristics in a dense oil producing area, the existing calibration area is compared through the geological conditions of the area to be evaluated, the development well characteristics of the area to be evaluated are determined, and then reserves with the development area are calculated. The similarity method needs a large amount of comparison data similar to the evaluated area, and when proper data is lacked, the oil gas productivity prediction precision is low; in addition, even if there are many comparison data, the difference in productivity will still be large in areas with the same parameters due to the heterogeneity of the tight oil reservoir, which directly affects the estimation of recoverable reserves, so the tight oil reserves obtained by the analogy method have low precision and cannot meet the production requirements.
The inventor of the application finds that due to the special pearly nature of the compact oil resource, when the conventional method is adopted for evaluation, the influences of geological factors, engineering factors and economic factors of the compact oil cannot be comprehensively considered, and finally the precision of the evaluation result is low.
Disclosure of Invention
In order to overcome the above defects in the prior art, embodiments of the present invention provide a method for evaluating the reserves of a tight oil well, so as to improve the accuracy of predicting the reserves of the tight oil well.
The embodiment of the invention has the following specific technical scheme:
a method for evaluating the reserves of a compact oil well comprises the following steps: grading different compact oil wells based on geological factors of compact oil well regions and the mining states of the compact oil wells, and further obtaining the abundance of each compact oil well in each stage of compact oil wells; obtaining the abundance plane distribution of the compact oil wells in the compact oil well regions based on the abundance of each compact oil well in each stage of compact oil wells; obtaining the economic coefficient of each compact oil well in each compact oil well based on the abundance of each compact oil well in each compact oil well, thereby dividing each compact oil well into different levels to obtain each class of compact oil wells; obtaining the area of each class of compact oil well based on the abundance plane distribution of the compact oil wells in the compact oil well region and each class of compact oil wells; obtaining the abundance of each type of compact oil well in each stage of compact oil well based on the economic coefficient of each compact oil well in each stage of compact oil well; and obtaining the reserves of the compact oil wells under each grade of compact oil based on the abundance of each grade of compact oil well in each grade of compact oil and the area of each grade of compact oil well, and evaluating the reserve condition of the compact oil well area.
According to the method for evaluating the reserves of the tight oil wells, the abundance distribution characteristics of each type of tight oil wells in each level of tight oil wells in the tight oil production area are determined by using the mode that the capacity of the tight oil is gradually changed under similar geological conditions, the recoverable reserves of the tight oil are evaluated by using the abundance parameter, and the defect that the yield data used in the prior art does not consider engineering factors is overcome. Then, the economic coefficient is used for dividing the abundance boundary of the compact oil well, the compact oil reserves are further classified, the reserves of different categories are determined, the reserve abundance boundary is determined by the economic coefficient, the reserve ranges of different categories can be divided on a plane, the reserve abundance condition can be visually reflected, the defect that the reserve distribution range and the reserve abundance of each category cannot be considered simultaneously in the prior art is overcome, the economic coefficient directly reflecting the current cost and the income is used as the boundary division standard, support is provided for the later economic evaluation of the block, and the defect that the economic feasibility of the compact oil exploitation is not considered in the existing method is overcome. Therefore, the evaluation method of the reserves of the compact oil well comprehensively considers geological factors, engineering factors, reserve distribution range, reserve abundance, economic factors and the like, and compared with the prior art which only considers part of factors influencing the reserve evaluation of the compact oil well, the result is more accurate and reliable, thereby providing reliable basis for the rapid optimization of the subsequent compact oil region.
Drawings
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes, the proportional sizes, and the like of the respective members in the drawings are merely schematic for facilitating the understanding of the present invention, and do not specifically limit the shapes, the proportional sizes, and the like of the respective members of the present invention. Those skilled in the art, having the benefit of the teachings of this invention, may choose from the various possible shapes and proportional sizes to implement the invention as a matter of case.
Fig. 1 is a schematic flow chart of a method for evaluating the reserves of a tight oil well according to an embodiment of the present invention.
FIGS. 2a-2h are schematic diagrams of different conditions of the different states of a plurality of different levels of the compact oil resource zones partitioned in the examples of the present invention.
FIG. 3 is a graph of production from a tight oil well of one type in an embodiment of the present invention.
FIG. 4 is a fitting graph of the primary resource block average EUR according to the embodiment of the present invention.
FIG. 5 is a fitting graph of secondary resource zone average EUR according to the embodiment of the present invention.
FIG. 6 is a plane distribution of EUR abundance of the whole tight oil well region in the example of the present invention.
FIGS. 7a-7c are areas of EUR abundance corresponding to each class of tight oil wells in examples of the present invention.
Detailed Description
The details of the present invention will become more apparent in light of the accompanying drawings and description of specific embodiments thereof. However, the specific embodiments of the present invention described herein are for the purpose of illustration only and should not be construed as limiting the invention in any way. Any possible variations based on the present invention may be conceived by the skilled person in the light of the teachings of the present invention, and these should be considered as falling within the scope of the present invention.
The embodiment of the invention discloses a method for evaluating the reserves of a tight oil well, and fig. 1 is a flow schematic diagram of the method for evaluating the reserves of the tight oil well in the embodiment of the invention, and as shown in fig. 1, the method for evaluating the reserves of the tight oil well comprises the following steps:
s101: grading different compact oil wells based on geological factors of compact oil well regions and the mining states of the compact oil wells, and further obtaining the abundance of each compact oil well in each stage of compact oil wells, wherein the method comprises the following steps:
s201: and grading different tight oil wells based on geological factors of the tight oil well area and the exploitation state of the tight oil well.
According to key geological factors influencing the tight oil recovery such as the thickness of the hydrocarbon source rock in the block, the organic matter abundance TOC, the organic matter maturity Ro, the thickness of the reservoir, the porosity of the reservoir and the oil saturation, the resource classification partition can be carried out on the tight oil resource in the block by combining the characteristics of the drilled initial yield, the produced oil-water ratio, the oil saturation and the like, the geological factors at least comprise one of the thickness of the hydrocarbon source rock in the block, the organic matter abundance TOC, the organic matter maturity Ro, the thickness of the reservoir, the porosity of the reservoir and the oil saturation, and the mining state of the tight oil well at least comprises one of the drilled initial yield, the produced oil-water ratio and the oil saturation.
The method is characterized in that the geological parameters are utilized to grade the compact oil resources, and the compact oil well area is divided into a plurality of compact oil production areas with different grades. The method has the advantages that the dense oil resources are classified and partitioned according to key geological factors influencing the yield of the dense oil, the maturity of the source rock, the abundance of organic matters, the thickness of a reservoir stratum and the like, and the defect that the geological factors are not comprehensively considered in the prior art is overcome; the average yield decreasing model is independently established in different levels, and the defect that the total reserve of the compact oil can not be obtained by using the decreasing model simulation in a part of wells with shorter production time is overcome.
The following are specific embodiments of the present invention: aiming at the geological condition of a certain block in North America, determining a main interval, a rock type and a rock combination type of dense oil production; determining geological factor characteristics of the block oil-producing hydrocarbon source rock by using geochemical data, wherein the geological factor characteristics comprise the plane distribution conditions of the thickness of the hydrocarbon source rock, the abundance (TOC) of organic matters, the type of the organic matters and the maturity (Ro) of the organic matters, and respectively reflecting the oil-producing capacity, the oil-producing quantity and the type of oil gas of the block oil-producing hydrocarbon source rock; determining block reservoir characteristics by using the well-drilled well logging information, wherein the block reservoir characteristics comprise planar distribution characteristics of thickness (part of area is equal to the thickness of the hydrocarbon source rock), porosity, pressure coefficient, oil saturation, burial depth and fracture; preliminarily determining the plane distribution characteristics of the dense oil productivity in the block by using the drilled test data or the production data; the geological parameter planes such as hydrocarbon source rocks and reservoirs are mainly considered, the division is performed according to resource region division standards in blocks by combining with the capacity distribution situation, the table 1 is the resource region division standards in the blocks, a plurality of non-level compact oil resource regions are comprehensively divided, and fig. 2a-2h are schematic diagrams of different state conditions of the divided plurality of different-level compact oil resource regions in the embodiment of the invention, as shown in fig. 2a-2 h.
TABLE 1 compact oil resource grading parameter Table
S202: and respectively determining yield decreasing models of all stages of compact oil wells based on the yield decreasing curves of all stages of compact oil wells.
Respectively establishing typical curves based on the yield decreasing curves of all levels of compact oil wells in the resource area, and determining the most appropriate yield decreasing model for simulating the yield decreasing curves of all levels of compact oil wells, wherein the yield decreasing model at least comprises one of an exponential decreasing model, a hyperbolic decreasing model, a tuning decreasing model, a hyperbolic-exponential decreasing model and the like.
In this embodiment, a hyperbolic-exponential decreasing model is selected for the research area, because the single hyperbolic decreasing model is easy to overestimate the recoverable reserves of the single well, the hyperbolic-exponential decreasing model is used to perform reasonable simulation prediction on the recoverable reserves of the single well. As the production time increases, the rate of decrease in yield gradually decreases, i.e., the rate of decrease per month D m When the value is 0.83 percent, the hyperbolic decreasing model is converted into an exponential decreasing model to prevent the decreasing model from generating obvious high errors in the prediction of the late production stage, wherein 0.83 percent is an exponential decreasing rate D e . FIG. 3 is a production curve diagram of a type of tight oil well in an embodiment of the present invention, and as shown in FIG. 3, the yield of each level of tight oil well decreases in a decreasing curve including a monthly decrease rate D m The current month decrement rate D m Greater than the exponential decrease rate D e When the model is determined to be hyperbolic decreasing model, the monthly decreasing rate D m Equal to the exponential decrement rate D e Then, determining the moment as a hyperbolic decreasing model and converting the hyperbolic decreasing model into an exponential decreasing model, wherein the monthly decreasing rate D m Less than exponential decay rate D e Then, the stage is determined to be an exponential decreasing model.
S203: the method comprises the following steps of obtaining the total recoverable reserve of each compact oil well in each stage of compact oil wells based on a yield decrement model of each stage of compact oil wells, wherein the method comprises the following steps:
in this example, production data for all the commissioned tight wells in the study area are selected and the final recoverable reserves are estimated in two stages as shown in FIG. 3.
S301: when the stage is a hyperbolic decreasing model, a decreasing exponential constant of the hyperbolic decreasing model is obtained based on the characteristics of the hyperbolic decreasing model and existing production data. The calculation formula of the decreasing exponential constant of the hyperbolic decreasing model is as follows:
q mt ＝q mi (1+bD mi t m ) -1/b (2)
wherein D is mi Represents the initial monthly decrement rate, q mi Denotes initial monthly yield, q mt Denotes the monthly yield at month t, t m Representing production time, b representing decreasing exponential constant of hyperbolic decreasing model, and existing production data including q mi And q is mt 。
Calculating to obtain an initial monthly decrement rate D by the formula 1 mi . In particular, where b =0 is an exponential decreasing model and b =1 is a harmonic decreasing model, b is generally less than 1 in the conventional decreasing hydrocarbon model, and b tends to be greater than 1 for unconventional hydrocarbons. Will D mi And stable production data q of 6-12 months or more mt Substituting into formula 2 to calculate the parameter b.
S302: rate of decline in the month D m Equal to the exponential decrement rate D e When the hyperbolic decreasing model is converted into the exponential decreasing model, the time is based on the exponential decreasing rate D e And obtaining the production time of the hyperbolic decreasing model stage.
When D is m ＝D e The hyperbolic decreasing model is converted into an exponential decreasing model, and the production time is t 1 The expression is:
wherein, t 1 Representing the production time of the hyperbolic decreasing model phase, i.e. from the beginning of production to the end of productionRate of decrease D e Production time of (D) e Representing the critical decreasing rate, b representing the decreasing exponential constant of the hyperbolic decreasing model, D mi Indicating the initial monthly decrement rate.
Calculating t by equation 3 1 。
S303: and obtaining the accumulated yield of the hyperbolic decreasing model stage based on the decreasing exponential constant of the hyperbolic decreasing model and the production time of the hyperbolic decreasing model stage.
Hyperbolic decreasing model phase cut-off to t 1 The monthly cumulative yield formula is:
wherein b represents a decreasing exponential constant of the hyperbolic decreasing model, q mi Denotes initial monthly yield, D mi Represents the initial monthly decrement rate, Q 1 Representing the cumulative yield of the hyperbolic decreasing model phase.
When t is m ＝t 1 Then, the q is calculated by substituting the equation into the formula 2 mt At this time, q mt I.e. the critical decrement rate D e Hourly capacity q e . Cumulative yield Q of hyperbolic decreasing model stage 1 Obtained by integrating equation 4:
wherein q is e Represents the critical decrement rate D e The productivity in time, b represents the decreasing exponential constant of the hyperbolic decreasing model, q mi Denotes initial monthly yield, D mi Represents the initial monthly decrement rate, Q 1 Representing the cumulative yield of the hyperbolic decreasing model phase.
Calculating the cumulative yield Q of the hyperbolic decreasing model stage according to the formula 5 1 。
S304: and obtaining the production time of the exponential decrement model stage based on the economic limit capacity.
In the same monthRate of decrease D m Less than exponential decay rate D e Then, the stage is an exponential decreasing model, and the monthly yield formula in the exponential decreasing model is as follows:
wherein, t m ＞t 1 ，q e Represents the critical decrement rate D e Hourly capacity, D e Represents the critical rate of decrease, t m Denotes the production time, q mt Represents the monthly yield at month t.
When q is mt ＝q z That is to say the monthly yield reaches the economic limit yield q z When it is time to stop mining, t 2 The expression is as follows:
wherein q is z Represents the economic limit capacity, t 2 Representing the production time of the exponential decay model phase, i.e. from the critical capacity q e Production time down to the limit of energy production in the economic world, D e Represents the critical rate of decrease, q e Represents the critical decrement rate D e The productivity is improved.
S305: and obtaining the accumulated yield of the exponential decreasing model stage based on the production time of the exponential decreasing model stage and the exponential decreasing model.
Integrating the formula 6 to obtain the cumulative yield Q of the exponential decreasing model stage 2 ：
Wherein Q is 2 To representCumulative yield of the exponential decreasing model phase, q e Represents the critical decrement rate D e Capacity of hour, D e Represents the critical rate of decrease, D m Represents the monthly decrement rate, t 2 Represents the critical capacity q e And reducing the production time of the decreasing model stage of the economic limit capacity index.
S306: and obtaining the total recoverable reserve of each compact oil well in each stage of compact oil wells based on the accumulated yield of the hyperbolic descending model stage and the accumulated yield of the exponential descending model stage.
Let t in equation 7 2 And substituting the formula 9, and further calculating the total recoverable reserve EUR of each compact oil well in each stage of compact oil wells:
EUR＝Q 1 +Q 2 (10)
wherein Q 1 Representing cumulative yield, Q, of hyperbolic decreasing model stages 2 The cumulative yield of the exponential decreasing model stage is shown, and the EUR represents the total recoverable reserves of each compact oil well in each stage of compact oil wells.
For tight wells that have been produced for more than 1 year, the capacity has reached a plateau and its EUR is calculated separately using step S103. For the part of wells which are produced for less than one year and cannot reach the stable production stage, b cannot be accurately calculated, and the prediction of EUR is further influenced. FIG. 4 is a graph of the average EUR of the primary resource area in the neighboring region according to the embodiment of the present invention, FIG. 5 is a graph of the average EUR of the secondary resource area in the neighboring region according to the embodiment of the present invention, as shown in FIGS. 4 and 5, a decreasing model is established by using the average production curve of the tight oil wells in the neighboring region, and parameters b and D are determined mi As b and D in a decreasing model of a non-steady-producing well mi A default value. Then, the initial yield of the well is combined, and the EUR of the well can be reasonably predicted by using the step S103.
S204: and obtaining the abundance of each compact oil well in each stage of compact oil wells based on the horizontal section length of each compact oil well, the discharge radius of each compact oil well and the total recoverable reserve of each compact oil well in each stage of compact oil wells.
Abundance EUR of each compact oil well in each compact oil well I The calculation formula of (c) is as follows:
S＝2Lr (12)
wherein, EUR I The abundance of each compact oil well in each stage of compact oil wells is shown, the EUR shows the total recoverable reserve of each compact oil well in each stage of compact oil wells, L shows the horizontal section length of each compact oil well, r shows the drainage radius of each compact oil well, and S shows the well control area. In this embodiment, the horizontal section length can be obtained from the drilling data of the horizontal well, and the average leakage radius of the tight oil well area is approximately half of the average well spacing of the production wells of the developed block in the neighboring area, which is about 400 m.
And determining the distribution characteristic of the total recoverable reserve abundance of the tight oil well region by using a model with gradually changed tight oil productivity under similar geological conditions. The method for evaluating the recoverable reserves abundance of the compact oil by utilizing the total recoverable reserves abundance parameter can overcome the defect that the yield data used in the prior art does not consider engineering factors.
S102: and obtaining the abundance plane distribution of the dense oil wells in the dense oil well region based on the abundance of each dense oil well in each level of dense oil wells.
FIG. 6 is a plane distribution of EUR abundance of the whole tight oil well region in the embodiment of the invention, and as shown in FIG. 6, software with an interpolation function is used for carrying out spatial interpolation on EUR abundance of different levels of single wells in the tight oil well region, so as to obtain the plane distribution of EUR abundance of the whole tight oil well region. In order to ensure the reliability of the interpolation of the block edge area, the production data of the compact oil well in the surrounding area outside the compact oil well area is collected as much as possible and is also used as a data point for interpolation. By utilizing the EUR abundance spatial interpolation method in the compact oil-well region, the defect that the reserves of the whole block can be evaluated only by mass production of wells in the prior art is overcome.
S103: and obtaining the economic coefficient of each compact oil well in each compact oil well based on the abundance of each compact oil well in each compact oil well, thereby dividing each compact oil well into different categories to obtain each compact oil well in each category.
Calculating the economic coefficient of each compact oil well in each compact oil well based on the abundance of each compact oil well in each compact oil well:
wherein k represents the economic coefficient of each compact oil well in each stage of compact oil well, p represents the current oil price, C represents the total drilling cost, EUR I And representing the abundance of each compact oil well in each stage of compact oil wells.
And dividing each stage of compact oil well into different categories according to the obtained economic coefficient, thereby obtaining compact oil wells of each category of each stage.
In the embodiment, the compact oil well is divided into 1P, 2P and 3P reserves according to an economic coefficient k, and the EUR abundance evaluation standard is adopted. The economic coefficient k is an economic index for measuring a single compact oil well, and the larger k represents the larger ratio of the corresponding benefit to the cost. In the compact oil-well area, the oil well is considered as a distant view resource when the economic coefficient k is less than or equal to 1, and the oil well is considered as a 3P recoverable reserve when k is greater than 1; k >1.5 the well is considered to be a 2P recoverable reserve; k >2 the well is considered to be 1P recoverable.
And (4) dividing the EUR abundance boundary by using the economic coefficient, further classifying the compact oil reserves, and determining the reserves of different types of 1P, 2P and 3P. The EUR abundance boundary is determined by using the economic coefficient, and the reserves ranges of different types of 1P, 2P and 3P can be divided on a plane, so that the calculation is carried out in the subsequent steps, the reserve abundance condition can be directly reflected, and the defect that the reserve distribution range and the reserve abundance of each level in the prior art can not be considered at the same time is overcome; economic coefficients directly reflecting current cost and income are used as the standard of boundary division, support is provided for economic evaluation of blocks in the later period, and the defect that the economic feasibility of the dense oil exploitation is not considered in the existing method is overcome.
S104: and obtaining the area of each class of compact oil well based on the abundance plane distribution of the compact oil well in the compact oil well region and each class of the compact oil well.
7a-7c show the areas of the EUR abundances corresponding to the tight oil wells in each class in the embodiment of the present disclosure, as shown in fig. 7a-7c, according to the abundance plane distribution of the tight oil wells in the tight oil well region and each class to which each tight oil well belongs on the abundance plane distribution of the tight oil wells in the tight oil well region, the abundance plane distribution may be gridded, and the area of each class of tight oil wells may be calculated by calculating the number of grids occupied by each tight oil well. The smaller the grid number division is, the more accurate the value obtained by final calculation is correspondingly.
S105: and obtaining the abundance of each type of compact oil well in each stage of compact oil well based on the economic coefficient of each compact oil well in each stage of compact oil well.
According to the known current oil price, well control area and total drilling cost, the abundance of each type of compact oil well in each stage of compact oil well is calculated based on the economic coefficient of each compact oil well in each stage of compact oil well, and the specific formula is as follows:
wherein, EUR ΙΙ The method comprises the steps of representing the abundance of each type of compact oil well in each stage of compact oil well, C being the total drilling cost, S representing the well control area, p representing the current oil price, and k representing the economic coefficient of each compact oil well in each stage of compact oil well.
In this example, the current oil price is $ 50/barrel, and the average cost of drilling a single well is 1.2X 10 7 US dollar, the average length of the horizontal section of a single well is 3000m, the discharge radius is 400m, namely the average well control area is 2.4 multiplied by 10 6 m 2 . And calculating the abundance of each type of compact oil well in each stage of compact oil wells according to the formula 14. When k =1 and k =15, k =2, the abundance ratio of the dense oil well corresponding to each category is 100 multiplied by 10 -3 bbl/m 2 、150×10 -3 bbl/m 2 、200×10 -3 bbl/m 2 。
S106: and obtaining the reserves of the compact oil wells under each grade of compact oil based on the abundance of each grade of compact oil well in each grade of compact oil and the area of each grade of compact oil well.
Obtaining the areas of all levels of compact oil wells on the abundance plane distribution of the compact oil wells in the compact oil well region, and calculating the reserves of the compact oil wells under all levels of various categories according to the abundance of all levels of compact oil wells in each type of compact oil and the areas of all levels of compact oil wells, wherein the calculation formula is as follows:
P＝ΣEUR ΙΙ ×S i (15)
wherein P represents the reserves of the tight oil wells under each class, EUR ΙΙ Representing the abundance of each type of compact oil well in each stage of compact oil well under a certain grid after gridding, S i The unit area of each grid after gridding is shown.
In this embodiment, the spatial interpolation software is used to perform gridding processing on the abundance plane distribution of the tight oil wells in the tight oil well region, and the reserves of the tight oil wells in each class are obtained through calculation in sequence. Table 2 shows the reserves of the tight oil wells in each category, and the calculation results of the above process are shown in table 2.
TABLE 2 reserves of tight oil wells at various levels and categories
Thus, the total dense oil-well area has 1.879 million barrels of 1P, 3.463 million barrels of 2P, and 4.503 million barrels of 3P. Additionally, 1589.7 million barrels of crude oil have been produced in the primary resource zone and 564.4 million barrels have been produced in the secondary resource zone based on the current cumulative production of the existing wells. Therefore, the residual available resources in the primary resource area are 3.534 hundred million barrels, and the residual available resources in the secondary resource area are 0.753 million barrels. Respectively calculating reserves of the compact oil wells under each grade according to the EUR abundance and the area of the 1P, 2P and 3P reserves; and calculating the residual recoverable reserve of the research area by combining the accumulated yield of the compact oil well area in the production well. According to the evaluation method for the reserves of the compact oil well, geological factors, engineering factors, reserve distribution range, reserve abundance, economic factors and the like are comprehensively considered, and compared with the prior art in which only one factor influencing the reserve evaluation of the compact oil well is considered, the result is more accurate and reliable, so that a reliable basis is provided for quick optimization of a subsequent compact oil area.
The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered in the protection scope of the present invention.
Claims (10)
1. The method for evaluating the reserves of the compact oil well is characterized by comprising the following steps of:
grading different compact oil wells based on geological factors of compact oil well regions and the mining states of the compact oil wells, and further obtaining the abundance of each compact oil well in each stage of compact oil wells;
obtaining the abundance plane distribution of the compact oil wells in the compact oil well regions based on the abundance of each compact oil well in each stage of compact oil wells;
obtaining the economic coefficient of each compact oil well in each compact oil well based on the abundance of each compact oil well in each compact oil well, thereby dividing each compact oil well into different categories to obtain each category of compact oil wells;
obtaining the area of each type of compact oil well based on the abundance plane distribution of the compact oil well in the compact oil well region and each type of each level of the compact oil well;
obtaining the abundance of each type of compact oil well in each stage of compact oil well based on the economic coefficient of each compact oil well in each stage of compact oil well;
and obtaining the reserves of the compact oil wells under each grade based on the abundance of each type of compact oil well in each grade of compact oil and the area of each type of compact oil well.
2. The method of evaluating tight oil well reserves according to claim 1, characterized by: in the step, different tight oil wells are classified based on geological factors of tight oil well regions and the mining states of the tight oil wells, and further the abundance of each tight oil well in each level of tight oil wells is obtained, the method comprises the following steps:
grading different compact oil wells based on geological factors of compact oil well regions and the mining states of the compact oil wells to further obtain the total recoverable reserve of each compact oil well in each stage of compact oil wells;
obtaining the abundance of each compact oil well in each stage of compact oil wells based on the horizontal section length of each compact oil well, the discharge radius of each compact oil well and the total recoverable reserve of each compact oil well in each stage of compact oil wells;
wherein the geological factors comprise at least one of source rock thickness, organic matter abundance TOC, organic matter maturity Ro, reservoir thickness, reservoir porosity and oil saturation within the block.
3. The method for evaluating the reserves of the tight oil well according to claim 2, wherein in the step of grading different tight oil wells based on the geological factors of the tight oil well region and the production state of the tight oil well to obtain the total recoverable reserves of each tight oil well in each stage of the tight oil wells, the method comprises the following steps:
grading different compact oil wells based on geological factors of the compact oil well region and the mining state of the compact oil well;
respectively determining yield decreasing models of all stages of compact oil wells based on the yield decreasing curves of all stages of compact oil wells;
and obtaining the total recoverable reserve of each compact oil well in each stage of compact oil wells based on the yield decreasing model of each stage of compact oil well.
4. The method of evaluating tight oil well reserves according to claim 3, characterized by: respectively determining yield decreasing models of all levels of compact oil wells based on the yield decreasing curves of all levels of compact oil wells, wherein the yield decreasing models at least comprise one of exponential decreasing models, hyperbolic decreasing models, tuning decreasing models and hyperbolic-exponential decreasing models; the yield of each stage of compact oil well comprises a monthly decrement rate D m The current month decrement rate D m Greater than the exponential rate of decrease D e When the period is determined to be a hyperbolic decreasing model, the monthly decreasing rate D m Equal to the exponential decrement rate D e Then, determining the moment as a hyperbolic decreasing model and converting the hyperbolic decreasing model into an exponential decreasing model, wherein the monthly decreasing rate D m Less than exponential decay rate D e Determining the stage as an exponential decreasing model;
in the step of obtaining the total recoverable reserve of each compact oil well in each compact oil well based on the yield decrement model of each compact oil well, the method specifically comprises the following steps:
when the stage is a hyperbolic decreasing model, a decreasing exponential constant of the hyperbolic decreasing model is obtained based on the hyperbolic decreasing model characteristic and existing production data;
rate of decline in the month D m Equal to the exponential decrement rate D e When the hyperbolic decreasing model is converted into the exponential decreasing model, the moment is based on the exponential decreasing rate D e Obtaining the production time of the hyperbolic decreasing model stage;
obtaining the accumulated yield of the hyperbolic decreasing model stage based on the decreasing exponential constant of the hyperbolic decreasing model and the production time of the hyperbolic decreasing model stage;
obtaining the production time of an index decreasing model stage based on the economic limit productivity;
obtaining the accumulated yield of the exponential decreasing model stage based on the production time of the exponential decreasing model stage and the exponential decreasing model;
and obtaining the total recoverable reserve of each compact oil well in each stage of compact oil wells based on the accumulated yield of the hyperbolic descending model stage and the accumulated yield of the exponential descending model stage.
5. The method of evaluating tight oil well reserves according to claim 4, characterized in that: when the stage is a hyperbolic decreasing model, a decreasing exponential constant of the hyperbolic decreasing model is obtained based on the hyperbolic decreasing model characteristic and the existing production data, and the specific formula is as follows:
q mt ＝q mi (1+bD mi t m ) -1/b
wherein D is mi Represents the initial monthly decrement rate, q mi Denotes initial monthly yield, q mt Denotes the monthly yield at month t, t m Representing production time, b representing decreasing exponential constant of hyperbolic decreasing model, and existing production data including D mi And q is mt 。
6. The method of evaluating tight oil well reserves according to claim 4, characterized by: decreasing rate D in the current month of step m Equal to the exponential decrement rate D e When the hyperbolic decreasing model is converted into the exponential decreasing model, the time is based on the exponential decreasing rate D e In the process of obtaining the production time of the hyperbolic decreasing model stage, a specific formula is as follows:
wherein, t 1 Representing the production time of the hyperbolic decreasing model phase, i.e. the critical decreasing rate D is reached from the beginning of production e Production time of (D) e Representing the critical decreasing rate, b representing the decreasing exponential constant of the hyperbolic decreasing model, D mi The initial monthly decrement rate is indicated.
7. The method of evaluating tight oil well reserves according to claim 4, characterized in that: in the step of obtaining the cumulative yield of the hyperbolic decreasing model stage based on the decreasing exponential constant of the hyperbolic decreasing model and the production time of the hyperbolic decreasing model stage, the concrete formula is as follows:
wherein q is e Represents the critical decrement rate D e Capacity in time, b represents the decreasing exponential constant of the hyperbolic decreasing model, q mi Denotes initial monthly yield, D mi Represents the initial monthly decrement rate, Q 1 Representing the cumulative yield of the hyperbolic decreasing model stage;
in the step of obtaining the production time of the exponential decreasing model stage based on the economic limit capacity, the specific formula is as follows:
wherein q is z Represents the economic limit capacity, t 2 Representing the production time of the exponential decay model phase, i.e. from the critical capacity q e Production time down to the limit of energy production in the economic world, D e Represents the critical rate of decrease, q e Represents the critical decrement rate D e Capacity per hour;
in the step of obtaining the accumulated yield of the exponential decreasing model stage based on the production time of the exponential decreasing model stage and the exponential decreasing model, the specific formula is as follows:
wherein Q is 2 Representing the cumulative yield of the exponential decay model stage, q e Represents the critical decrement rate D e Capacity of hour, D e Represents the critical rate of decrease, D m Denotes the monthly decrement rate, t 2 Represents the critical capacity q e Reducing the production time to the economic limit productivity index decreasing model stage;
in the step of obtaining the total recoverable reserve of each compact oil well in each stage of compact oil wells based on the accumulated yield of the hyperbolic decreasing model stage and the accumulated yield of the exponential decreasing model stage, the specific formula is as follows:
EUR＝Q 1 +Q 2
wherein Q 1 Representing cumulative yield, Q, of hyperbolic decreasing model stages 2 The cumulative yield of the exponential decreasing model stage is shown, and the EUR represents the total recoverable reserves of each compact oil well in each stage of compact oil wells.
8. The method of evaluating tight oil well reserves according to claim 2, characterized in that: in the step of obtaining the abundance of each compact oil well in each stage of compact oil wells based on the horizontal section length of each compact oil well, the discharge radius of each compact oil well and the total recoverable reserve of each compact oil well in each stage of compact oil wells, the specific formula is as follows:
S＝2Lr
wherein, EUR I The abundance of each compact oil well in each compact oil well is shown, the EUR represents the total recoverable reserve of each compact oil well in each compact oil well, the L represents the horizontal section length of each compact oil well, the r represents the discharge radius of each compact oil well, and the S represents the well control area.
9. The method of evaluating tight oil well reserves according to claim 1, characterized in that: in the step, the economic coefficient of each compact oil well in each compact oil well is obtained based on the abundance of each compact oil well in each compact oil well, so that each compact oil well is divided into different categories to obtain each compact oil well in each category, and the specific formula of the economic coefficient of each compact oil well in each compact oil well is as follows:
wherein k represents the economic coefficient of each compact oil well in each stage of compact oil wells, p represents the current oil price, C represents the total drilling cost, and EUR I Representing the abundance of each compact oil well in each stage of compact oil wells;
in the step of obtaining the abundance of each type of compact oil well in each stage of compact oil well based on the economic coefficient of each compact oil well in each stage of compact oil well, the concrete formula is as follows:
wherein, EUR ΙΙ The method comprises the steps of representing the abundance of various types of compact oil wells in various stages of compact oil wells, C representing the total drilling cost, S representing the well control area, p representing the current oil price, and k representing the economic coefficient of each compact oil well in various stages of compact oil wells.
10. The method of evaluating tight oil well reserves according to claim 1, characterized in that: in the step of obtaining the reserves of the compact oil wells under each class based on the abundance of each class of compact oil wells in each class of compact oil and the area of each class of compact oil wells, the specific formula is as follows:
P＝∑EUR ΙΙ ×S i
wherein P represents the reserves of the tight oil wells under each class, EUR ΙΙ Representing classes in tight oil wells at all levelsAbundance of tight oil wells, S i The unit area of each grid after gridding is shown.
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| CN107423844B (en) * | 2017-06-06 | 2018-06-26 | 西南石油大学 | A kind of new method for predicting shale gas/tight gas wells recoverable reserves |
| CN107152277B (en) * | 2017-06-07 | 2020-11-10 | 长江大学 | Method and system for calculating residual oil saturation degree through carbon-oxygen ratio logging |
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| CN109555517A (en) * | 2018-10-30 | 2019-04-02 | 中国石油大学胜利学院 | For the coal bed gas proved reserves property employed quantitative evaluation method |
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