A sand body quantitative prediction method based on source-sink mass conservation

Abstract

The application discloses a sand body quantitative prediction method based on source-sink material conservation, which comprises the following steps: calculating the annual average supply of a source area around a sedimentary basin through a sediment flux calculation model; calculating the product of the stratigraphic deposition time of the source area and the annual average supply to obtain the supply of the source area; calculating the total deposition of a deposition area in each source direction of the sedimentary basin through a deposition amount calculation formula; calculating the difference between the source supply of the source area and the total deposition of the deposition area as a deposition difference; substituting the deposition difference into the deposition amount calculation formula to inversely calculate the possible distribution area of the sand body under the condition that the stratigraphic thickness is the largest, and the possible development thickness of the stratigraphic layer under the condition that the sand body has the largest area; and predicting the development scale of the sand body in a depression area based on the distribution area and the development thickness. The application can quantitatively predict the development scale of the sand body in a low exploration degree and low data quality area, and provide a geological basis for sand body distribution description and exploration and development well site deployment in a coal measure stratum depression area.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sand body prediction technology in low exploration degree area, and particularly relates to a sand body quantitative prediction method based on source-sink material conservation. BACKGROUND

[0002] When a petroliferous basin enters the middle and late exploration period, the exploration object changes from structural oil and gas reservoirs to lithologic oil and gas reservoirs, the exploration field changes from the middle and shallow layers to the deep layers, and changes from the pericratonic positive structural belt to the depression area, and the exploration difficulty is getting greater and greater, so the sand body development scale in the depression area restricts the exploration and development of the petroliferous basin. At the same time, due to the low exploration degree in the depression area, there is a lack of drilling data, and it is difficult to predict the sand body development scale by the geological method. For the coal measure strata, due to the relatively low quality of the seismic data, the seismic method has low reliability in predicting the sand body development scale. SUMMARY

[0003] The present application aims to quantitatively predict the sand body development scale in the depression area of the coal measure strata by the relative conservation law of the source-sink system. To this end, the present application provides a sand body quantitative prediction method based on source-sink material conservation.

[0004] The present application provides a sand body quantitative prediction method based on source-sink material conservation, which comprises the following steps:

[0005] calculating the annual average supply amount of the source area around the sedimentary basin by a sediment flux calculation model;

[0006] calculating the product of the stratum deposition time of the source area and the annual average supply amount to obtain the supply amount of the source area;

[0007] calculating the total deposition amount of the deposition area in each source direction of the sedimentary basin by a deposition amount calculation formula;

[0008] calculating the difference between the source supply amount of the source area and the total deposition amount of the deposition area as a deposition difference;

[0009] substituting the deposition difference into the deposition amount calculation formula to inversely calculate the possible distribution area of the sand body under the condition that the stratum thickness is the largest, and the possible development thickness of the stratum under the condition that the sand body area is the largest;

[0010] predicting the development scale of the sand body in the depression area based on the distribution area and the development thickness.

[0011] Another aspect of the present application provides a computer readable storage medium having a computer program stored thereon, wherein the program is executed by a processor to implement the above method.

[0012] In still another aspect, an embodiment of the present application provides a computer device, comprising a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor implements the method described above when running the program.

[0013] The embodiments of the present application can quantitatively predict the development scale of sand bodies in a low exploration degree and low data quality area, and provide a geological basis for sand body distribution delineation and exploration and development well site deployment in a coal measure stratum depression area.

[0014] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0015] The technical solutions of the present application will be further described in detail below with the help of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate embodiments of the present application and explain the present application, and do not constitute a limitation of the present application. In the drawings:

[0017] Figure 1 A sedimentary facies and sand body distribution characteristic map is shown;

[0018] Figure 2 A comparison chart of source supply amount and sedimentation total amount of different source-sink systems of the Jurassic Sangonghe Formation in the Turpan Depression is shown;

[0019] Figure 3 A flowchart of the sand body quantitative prediction method based on source-sink mass conservation according to the embodiments of the present application is shown. DETAILED DESCRIPTION

[0020] Exemplary embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood, and the scope of the present disclosure can be accurately conveyed to those skilled in the art.

[0021] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The following description is made with reference to the accompanying drawings in which like reference numerals designate identical or similar elements in the several views. The implementations described in the following exemplary embodiments are not meant to represent all implementations consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0022] The inventor found in the process of studying the problems in the prior art that the sand body prediction method is relatively mature in relatively high exploration degree areas at home and abroad, including through sand ratio, sand thickness mapping, grain size variation or facies sequence evolution law, sedimentary mode or sand body configuration, water tank experiment or numerical simulation, etc. Even in the case of no well area and relatively high quality seismic data, sedimentary boundaries and sand bodies can be described through various seismic attributes or seismic sedimentology methods. Therefore, for the thickness, area and other scale problems of sand bodies in low exploration degree and low data quality areas, traditional geology and geophysics means are difficult to give quantitative answers.

[0023] The research on source-sink system and theory at home and abroad is in the qualitative-semiquantitative analysis stage. On the one hand, due to the limitation of research data or the influence of post-tectonic evolution, the source-sink system during the deposition period and the mutual influence between them are uncertain. Secondly, the supply amount of different basin source areas is calculated by using empirical formula, which has certain applicable conditions. Finally, the sedimentation amount calculation formula of different sedimentary systems is different, and there are a lot of uncertain factors or subjective adjustments. Therefore, various source-sink system quantitative calculation methods are difficult to popularize and apply.

[0024] Chinese patent CN112051626A discloses a quantitative characterization method of source-sink system, on the basis of qualitative analysis of sedimentary system, a sediment volume calculation formula based on three parameters of terrain height difference, catchment area and valley cross-sectional area is proposed;

[0025] Chinese patent CN112327355A discloses a paleogeomorphology restoration method based on source-sink system, by restoring the source and calculating the denudation amount, the paleogeomorphology and prototype basin during the deposition period are established;

[0026] Chinese patent CN113935153A discloses a paleo-water system quantitative restoration and picking method based on source-sink-ArcGIS system, which uses remote sensing images and digital elevation model to obtain the source boundary and transport channel characteristics;

[0027] A kind of source-sink system quantitative evaluation method is disclosed in Chinese patent CN113960288A, which is used to quantitatively evaluate the relative contribution amount of known sediments from different source areas at different time steps. The above patent is limited to the quantitative study of source supply amount of source area, and has not carried out quantitative study of sediment amount of sedimentary basin, and has not quantitatively predicted unknown sediments from the perspective of source-sink material conservation law.

[0028] In addition, many literatures have been published at home and abroad about the application of BQART calculation model of source area sediment flux and the improvement of the model and a large number of sedimentation rate calculation formula (Syvitski and Milliman, 2007; Nyberg et al., 2021; Wang Xuewen et al., 2022; Chen Xingyu et al., 2023), and there is no corresponding calculation method for sedimentation amount of sedimentary basin with the same dimension as source supply amount of source area, so it is impossible to achieve the purpose of predicting the development scale of sand body in unwell area through source-sink system quantitative calculation.

[0029] The present embodiment provides a sand body quantitative prediction method based on the source-sink material conservation law, as shown in Figure 3 The method comprises the following steps:

[0030] Step 100, the source system of the surrounding source area of the sedimentary basin is determined by a plurality of methods such as heavy mineral combination, cutting composition, parent rock tracking, zircon age comparison, sediment structure characteristics and modern sediment analogy, so as to determine the source area.

[0031] Step 200, the annual supply amount of the source area around the sedimentary basin is calculated by a sediment flux calculation model.

[0032] The sediment flux calculation model is specifically BQART model, as shown in the following formula:

[0033] Q s = ω × B × Q 0.31 × A 0.5 × R × T

[0034] In the formula, Q s is the sediment flux (Mt / a), ω is a constant (Q s is 0.0006 when the unit is Mt / a), B is a geological factor (considering the basement lithology, dimensionless), Q is runoff (km 3 / a), A is the area of the basin (km 2 ), R is the elevation difference (km), and T is the annual average temperature (℃).

[0035] Among them, parameters B and Q come from empirical factors in geological database, parameters A and R can be obtained according to the method provided in Chinese patent CN113935153A, and parameter T can be obtained by pollen analysis and trace element analysis of ancient temperature.

[0036] Step 300: Calculate the supply of the source area by multiplying the sediment deposition time of the source area by the average annual supply.

[0037] Specifically, as shown in the following formula:

[0038] P t =Q s ×T s

[0039] In the formula: P t Q represents the material supply (Mt) of the material source region. s T represents the deposition flux (Mt / a). s The deposition time is expressed in Ma.

[0040] Wherein, parameter Ts represents the deposition time of the strata.

[0041] Step 400: Determine the deposition zone in each source direction.

[0042] Specifically, the sedimentary system and sand body genetic type of the sedimentary basin are determined by drilling cores, well logging, or seismic data, and the sand body correlation, sandstone thickness, and sand-to-land ratio distribution are determined vertically or along the source direction. Based on the results of the determination, as well as the reconstruction of the prototype basin, paleogeographic features, and seismic attributes, a lithofacies paleogeographic map of the sedimentary period is compiled. Based on the lithofacies paleogeographic map of the sedimentary period, the sedimentary areas in each source direction are determined.

[0043] Step 500: Calculate the total sediment volume of the sedimentary areas in each source direction of the sedimentary basin using the sediment volume calculation formula.

[0044] The formula for calculating the deposition amount is as follows:

[0045] D t = a × b × S × H × ρ ÷ cosα

[0046] In the formula: D t Let Mt be the total sedimentary volume of the sedimentary area, a be the sedimentary factor (dimensionless), b be the tectonic factor (dimensionless), and S be the area of ​​later erosion or residual strata (km²). 2 H is the formation thickness (m), and ρ is the formation density (g / cm³). 3 ), where α is the slope (°).

[0047] Among them, parameter a (sedimentary factor) comes from drilling data, parameter b (tectonic factor) comes from equilibrium profile recovery data, parameters S, H, and ρ are obtained from drilling data, and parameter α can be obtained from the slope of modern sedimentary analogy.

[0048] Step 600, calculate the difference between the source supply amount of the source area and the total amount of deposition of the deposition area as the deposition difference.

[0049] Wherein, the deposition difference is obtained by subtracting the source supply amount from the total amount of deposition according to the conservation of matter.

[0050] Specifically, according to the source-sink conservation law, the total amount of deposition is equal to the source supply amount, S t ≈P t Thus, the difference between the source supply amount of each source area and the total amount of deposition of the deposition area is calculated, that is, the deposition difference, as shown in the following formula:

[0051] D d =P t -D t

[0052] In the formula, D d is the deposition difference (Mt), P t is the source supply amount of the source area (Mt), D t is the total amount of deposition of the deposition area (Mt).

[0053] The size of the deposition difference of different source-sink systems reflects the exploration degree and the remaining exploration potential. The smaller the deposition difference, the higher the exploration degree; the larger the deposition difference, the greater the exploration potential of the sag area of the source-sink system (the size of the undiscovered sand body is large).

[0054] Step 700, substitute the deposition difference into the deposition amount calculation formula to inversely calculate the possible distribution area of the sand body under the condition of the maximum formation thickness, and the possible development thickness of the formation under the condition of the maximum sand body area.

[0055] The deposition amount calculation formula is as shown above in step 500; the inverse calculation process in this step is as shown in the following formula:

[0056] D d =a×b×S′×H′×ρ÷cosα

[0057] S′=(D d ×cosα)÷(a×b×ρ×H max )

[0058] H′=(D d ×cosα)÷(a×b×ρ×S max )

[0059] In the formula, S' is the possible distribution area of the sand body in the sag area (km 2), representing the possible sand body distribution area in the case of the maximum formation thickness; H' is the possible development thickness (m) of the formation in the depression area, representing the possible development thickness of the formation in the case of the maximum sand body area. H max The maximum formation thickness known in the study area is S max The residual maximum area in the depression area is H

[0060] Step 800, predicting the development scale of the sand body in the depression area based on the distribution area and the development thickness.

[0061] Specifically, the plan and profile of the sedimentary facies and sand body distribution can be compiled based on the distribution area and the development thickness of the sand body, and the development scale can be predicted according to the plan and profile.

[0062] Step 900, verifying the reliability of the source-sink material conservation sand body quantitative prediction method.

[0063] The first step is to verify the reliability of the calculation results, and whether the size ratio between the supply amount (P t ) of different source areas and the size ratio between the total amount of deposition (D t ) are consistent to verify whether the calculation results of the supply amount calculated in the above step 300 and the total amount of deposition calculated in the above step 500 are relatively reliable.

[0064] The second step is to verify the reliability of the prediction results of the sand body, and the prediction results of the development scale in the above step 800 can be verified according to the sandstone thickness revealed by the later drilling well and the sand body area depicted by the newly deployed three-dimensional data.

[0065] The method described in the embodiment can quantitatively predict the development scale of the sand body in the low exploration degree and low data quality area, and provide a geological basis for the sand body distribution depiction and exploration and development well site deployment in the depression area of the coal measure stratum.

[0066] To verify the above technical effects, the inventors of the present application also take the Jurassic Sangonghe Formation 2 member in the Turpan Depression of the Turpan-Hami Basin as an example to elaborate the present application in detail:

[0067] 1. Four major sources are determined by multiple methods

[0068] Four major source systems of northwest, north, southeast and southwest are determined by five methods of heavy mineral assemblage, detrital composition + parent rock tracing, zircon age comparison, sedimentary structure characteristics and modern sediment analogy.

[0069] The heavy mineral assemblage is mainly analyzed by analogy based on pie charts made from heavy mineral data. The rock fragment composition is mainly analyzed by microscopic identification and statistical analysis of the composition and content of rock fragments from different wells. The parent rock tracing is mainly based on the rock fragment composition and the stratigraphic distribution and lithological characteristics in the current geological map of the basin periphery to determine the parent rock area. The zircon age comparison is mainly verified by comparing the zircon ages and peak values ​​of different wells with the characteristics of samples from the parent rock area. The sedimentary structure characteristics are mainly determined by the lithological assemblage, bedding scale, and the zonal distribution of mud and gravel to determine the source of material in multiple directions. The modern sedimentary analogy is mainly based on the runoff and sedimentary characteristics of the modern intermontane basin, Barkol Basin.

[0070] 2. Quantitatively calculate the material supply of the four major material source areas.

[0071] First, the deposition flux is calculated using the BQART model:

[0072] Q s =ω×B×Q 0.31 ×A 0.5 ×R×T

[0073] In the formula: Q s Let ω be the deposition flux (Mt / a) and ω be a constant (Q). s (Unit: Mt / a, 0.0006), B is a geological factor (considering basement lithology, dimensionless), and Q is runoff (km²). 3 / a), where A is the drainage area (km²) 2 R is the elevation difference (km), and T is the average annual temperature (°C).

[0074] Geological factors, based on the composition of the parent rock, range from 1.5 to 1.8; runoff volume, referencing the runoff characteristics of the modern intermontane basin in Barkol, ranges from 30 to 36 km. 3 / a, the drainage area is estimated based on the exposed old strata on the geological map, the elevation difference is taken as 0.15-0.30 km with reference to the modern elevation and the uplift time of the mountain system, and the annual average temperature is taken as 25℃ with reference to the warm-hot and humid climate (Table 1).

[0075] After obtaining the sediment flux calculation results, the sediment supply of each source region is obtained by multiplying the stratigraphic deposition time by the average annual sediment flux of the source region:

[0076] P t =Q s ×T s

[0077] In the formula: P t Q represents the material supply (Mt) of the material source region. s T represents the deposition flux (Mt / a). s The deposition time is expressed in Ma.

[0078] 3. Compile lithofacies paleogeographic maps of the sedimentary period based on existing data.

[0079] By analyzing well core, logging, and seismic data, the sedimentary system and sand body genetic types were determined. Vertical and longitudinal sand body correlation, sandstone thickness, and sand-to-land ratio distributions were analyzed. Combined with prototype basin reconstruction, paleogeographic features, and seismic attributes, a lithofacies paleogeographic map of the sedimentary period was compiled. The study area is primarily a braided river delta-lacustrine sedimentary system, mainly developing five subfacies: upper plain, lower plain, frontal, and prodelta-shallow lacustrine. Figure 1 The Taipei Depression contains eight braided river deltaic clusters: Pubei, Qialekan, Keqia-Shanle, Zhaobishan, Xiaocaohu, Hongtai-Gedatai, Wenjisang, and Shengbei. Figure 1 As shown, the Sangonghe Formation has developed eight braided river delta bodies with four major sources of sediment. The sand bodies at the front edge are rich in the depression. Wells Qintan 1 and Ji 7 have confirmed the development of large-scale thick sand bodies in the depression area.

[0080] 4. Quantitatively calculate the sediment volume of 8 large bodies from 4 major sediment sources.

[0081] The sedimentary amounts of different subfacies from various sources in the study area were calculated using the sedimentary amount calculation formula:

[0082] D t = a × b × S × H × ρ ÷ cosα

[0083] In the formula: D t Let Mt be the total sedimentary volume of the sedimentary area, a be the sedimentary factor (dimensionless), b be the tectonic factor (dimensionless), and S be the area of ​​later erosion or residual strata (km²). 2 H is the formation thickness (m), and ρ is the formation density (g / cm³). 3 ), where α is the slope (°).

[0084] The sedimentary factor, derived from well data, represents the proportion of terrigenous supply in sediments to the total strata. Taking the lower plain subfacies of the study area as an example, this subfacies contains coal-bearing strata. The coal seams are primarily in-situ deposits, and their thickness accounts for 40% of the total strata thickness. Therefore, the terrigenous supply is 60%, and the sedimentary factor for the lower plain subfacies is set to 0.6. The sedimentary factors for the upper plain, lower plain, foreland, and prodelta subfacies of the study area are 1.0, 0.6, 0.9, and 0.3, respectively.

[0085] The tectonic factors are derived from data reconstructed from balanced profiles to eliminate stratigraphic duplication caused by tectonic thrust. Taking the northern piedmont zone of the study area as an example, the Bogda Mountains in the north thrust southward for approximately 12 km, resulting in a current north-south width of about 60 km for the study area. Based on the ratio between the original and current width of the study area, the tectonic factor for the northern piedmont zone is set to 1.2. The tectonic factors for the northern piedmont zone, the southern thrust zone, and the east-west trending tectonic zone are 1.2, 1.1, and 1.0, respectively.

[0086] The area of each subfacies in the study area is estimated from the prototype basin boundary and the present residual strata boundary. The slope data of each subfacies in the study area are obtained from the modern intermontane basin survey, mainly referring to the Barkol Basin (similar to the Tuha Basin, also an intermontane basin), the upper plain, the lower plain and the front slope are 6.0°, 1.5° and 4.5° respectively. The strata thickness and strata density data are obtained from drilling and logging.

[0087] The total sedimentary amount in each source direction is shown in Table 2.

[0088] 5、Based on the source-sink mass conservation law to predict the sand body development scale

[0089] According to the source-sink mass conservation law (D t ≈P t ), the difference between the source supply amount in different source directions and the sedimentary amount of the sedimentary area (i.e. the sedimentary difference) is calculated:

[0090] D d =P t -D t

[0091] In the formula: D d is the sedimentary difference (Mt), P t is the source supply amount of the source area (Mt), and D t is the total sedimentary amount of the sedimentary area (Mt).

[0092] After obtaining the sedimentary difference, the possible distribution area of the sand body under the condition of the maximum strata thickness and the possible development thickness of the strata under the condition of the maximum sand body area are calculated according to the sedimentary amount calculation formula:

[0093] D d =a×b×S′×H′×ρ÷cosα

[0094] In the formula: S′ is the possible distribution area of the sand body in the depression area (km 2 ), and H′ is the possible development thickness of the strata in the depression area (m).

[0095] The total sedimentary amount calculated from the northwest and southeast sources is consistent with the source supply amount calculated by the BQART model. The source supply amount of the north and southwest directions is greater than the total sedimentary amount, and the sedimentary difference is 0.2×10 6 Mt and 0.43×10 6 Mt respectively (Table 3). After obtaining the sedimentary difference in these two source directions, the sand body distribution scale in the depression area can be predicted. Taking the north source of Xiaocaohu depression as an example, the maximum possible newly added sand body area is 400 km 2 , and the maximum thickness of the sedimentary strata can reach 156 m. According to the average sand-to-ground ratio of 50%, the cumulative thickness of the sand body can reach 78 m.

[0096] 6. Revision of the depositional facies and sand body distribution map

[0097] According to the predicted new sand body area in the sag area, the depositional facies and sand body distribution map of the target layer is revised. The study area develops 4 major sources and 8 major braided river delta lobes. The Taibei sag, including the Qiudong, Shengbei and Xiaocaohu sub-sags, has the characteristics of full-sag and rich sand. It is predicted that the favorable exploration area of the front without drilling is up to 1200km 2 , mainly including the Qiudong sag southeast source, Shengbei sag northwest source, north source and Xiaocaohu sag north source sand body. At the same time, it is predicted that the Shengbei sag, Xiaocaohu sag and Tuokexun sag still have a certain scale of sand body development area.

[0098] 7. Reliability verification of source-sink material conservation sand body quantitative prediction method

[0099] According to the calculation results of source supply and total sedimentation Figure 2 , the source supply of the north source (northwest source + north source) in the Taibei sag is about 2 times that of the south source (southeast source + southwest source), and the total sedimentation is also about 2 times, which indicates the relative reliability of the calculation results. Secondly, the sedimentary difference of each source-sink system is small in general, which is consistent with the geological understanding of full-sag and rich sand in the Taibei sag, among which the sedimentary difference of the southeast source is the smallest and the southwest source is the largest, which is consistent with the high exploration degree of the Qiudong sag and the low exploration degree of the Xiaocaohu sag, which further indicates the reliability of the calculation results Figure 2 . Through the prediction of the development scale of sand body in the Qiudong sag by this method, the newly drilled 6 exploration wells in the J7 block of the Qiudong sag confirmed the development of sand body with a thickness of 50-80m and an area of 270km 2 , which indicates that the source-sink material conservation sand body quantitative prediction method is reliable. As shown in Figure 2 , the source supply and total sedimentation of the north source (northwest source, north source) are larger, and those of the south source (southeast source, southwest source) are smaller; secondly, the sedimentary difference of each source-sink system is small in general, among which the sedimentary difference of the southeast source is the smallest and the southwest source is the largest.

[0100] Through the above experimental examples, it is concluded that in the prediction of the Jurassic Sangonghe Formation sand body in the Tuha Basin, the coal measure strata braided river delta "full-sag and rich sand" is concluded, and it is confirmed after the completion of drilling of 6 wells in the J7 block of the Qiudong sag. It is predicted that the north source of the Xiaocaohu sag and the southwest source of the Shengbei sag may each add 400km 2 of sand body area, which provides a basis for the next well deployment.

[0101] The relevant data is shown in Tables 1 to 3 as follows:

[0102] Table 1 Source supply statistics table of four major source areas of the Jurassic Sangonghe Formation in the Turpan Depression

[0103]

[0104] Table 1 shows the calculated results of the material supply in the source areas. The northwest and northern source areas are roughly equivalent, as are the southeast and southwestern source areas. The northern area (northwest and northern source areas) is about twice that of the southern area (southeast and southwestern source areas), which is consistent with actual drilling data.

[0105] Table 2. Statistical table of Jurassic Sangonghe Formation sediments in the Turpan Depression

[0106]

[0107]

[0108] Table 2 shows the calculation results of the total sediments in the sedimentary basin. The total sediments from the northwest and southeast source areas are basically consistent with the source supply calculated in Table 1, and the proportion of total sediments is also consistent with the proportion of source supply.

[0109] Table 3. Sedimentation of the Sangonghe Formation of the Jurassic System in the Turpan Depression and Prediction of Sand Bodies in Well-Free Areas

[0110]

[0111] Table 3 shows the differences in total sediment volume and sediment supply between the northern and southwestern source regions. Based on the law of conservation of source and sink materials, taking the northern source region of the Xiaocaohu Depression as an example, the maximum possible newly added sand body area is 400 km². 2 The maximum thickness of the sedimentary strata may reach 156m. Based on a sand-to-soil ratio of 50%, the cumulative thickness of the sand body is estimated to be 78m, consistent with the sand body thickness of the newly completed wells in the Ji 7 blocks of the Qiudong Depression.

[0112] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0113] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0114] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0115] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for quantitatively predicting a sand body based on source-sink mass conservation, characterized in that, The method comprises the following steps: calculating the annual average supply of a source area around a sedimentary basin by a sediment flux calculation model; calculating the product of the stratigraphic deposition time of the source area and the annual average supply to obtain the supply of the source area; calculating the total deposition of a deposition area in each source direction of the sedimentary basin by a deposition amount calculation formula; calculating the difference between the source supply of the source area and the total deposition of the deposition area as a deposition difference; substituting the deposition difference into the deposition amount calculation formula to inversely calculate the possible distribution area of the sand body under the condition of the maximum stratigraphic thickness and the possible development thickness of the stratigraphic layer under the condition of the maximum sand body area; predicting the development scale of the sand body in the depression area based on the distribution area and the development thickness; the sediment flux calculation model is as follows: Q s = ω x B x Q 0.31 x A 0.5 x R x T where: Q s is the sediment flux, ω is a constant, B is a geological factor, Q is the runoff, A is the basin area, R is the elevation difference, and T is the average annual temperature. the annual average temperature is obtained by pollen analysis and trace element analysis of paleo-temperature; the deposition amount calculation formula is as follows: D t = a x b x S x H x p ÷ cos a where: D t is the total amount of deposition in the depositional area, a is the depositional factor, b is the structural factor, S is the area of post-depositional erosion or remaining strata, H is the strata thickness, p is the strata density, and a is the slope, obtained from modern sedimentary analogs. the inverse calculation comprises the following steps: D d = a x b x S' x H' x p ÷ cos a S' = (D d × cos α) ÷ (a × b × p × H max ) H' = (D d × cos α) ÷ (a × b × p × S max ) wherein: S' is the possible distribution area of the sand body in the depression area, H' is the possible development thickness of the stratum in the depression area, H max is the known maximum stratum thickness in the study area, S max is the residual maximum area of the depression area.

2. The method of claim 1, wherein, before calculating the total deposition, the following steps are further included: judging the sedimentary system and the sand body genetic type of the sedimentary basin by drilling core, logging or seismic data, and comparing the sand body, sandstone thickness and sandstone ratio distribution vertically or along the source direction; compiling a sedimentary facies paleogeographic map based on the results of the judgment and the prototype basin restoration, paleogeomorphologic features and seismic attributes; determining the deposition area in each source direction based on the sedimentary facies paleogeographic map.

3. The method of claim 1, wherein, before calculating the annual average supply of the source area, the following steps are further included:

4. The method of claim 1, wherein, determining the source area by heavy mineral assemblage, detrital composition, parent rock tracing, zircon age comparison, sedimentary structure features and modern sediment analogy.

5. The method of claim 1, wherein, predicting the development scale of the sand body in the depression area based on the distribution area and the development thickness of the sand body comprises the following steps: based on the distribution area and the development thickness of the sand body, revising the planar and profile maps of the sedimentary facies and sand body distribution, and predicting the development scale according to the planar and profile maps.

6. The method of claim 1, wherein, further comprising the following steps: verifying the reliability of the calculation results of the supply and the total deposition according to whether the size ratio between the supplies of different source areas is consistent with the size ratio between the total depositions.

7. A computer readable storage medium having stored thereon a computer program, characterized in that, further comprising the following steps:

8. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that, verifying the reliability of the prediction results of the development scale according to the sandstone thickness revealed by later drilled wells and the sand body area depicted by newly deployed three-dimensional data. The program is executed by a processor to implement the method according to any one of claims 1-6. The processor executes the program to implement the method according to any one of claims 1-6.

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