A method for predicting sedimentary sand body thickness based on quantitative calculation of erosion and deposition flux

Abstract

The present invention relates to the technical field of geological exploration, and more specifically, to a method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and deposition flux. By quantitatively calculating the size relationship between the erosion amount and the deposition flux, the distribution law of the sedimentary sand body and the predicted thickness are obtained, and the quantitative characterization of the erosion amount and the deposition flux is realized to comprehensively predict the thickness of the sedimentary sand body. The prediction accuracy is high, and the evaluation of key exploration areas and the optimization of targets are effectively supported, and the drilling of targets in complex areas is promoted, and good oil and gas displays are obtained through drilling, which effectively solves the technical problem that there is no method for predicting the thickness of sedimentary sand bodies based on quantitative calculation of erosion amount and deposition flux in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of geological exploration, and more specifically, to a method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux. Background Art

[0002] The paleo-geomorphology determines the size of the provenance area and the total amount of sedimentation in the sedimentary area. The lithology of the denuded parent rock determines the original material composition of the reservoir and affects the quality of the reservoir. The main paleo-geomorphology restoration methods include backstripping, original slope angle restoration, fault analysis, etc. Previous research methods mainly focus on the restoration of the amount of denudation of sedimentary strata and paleo-geomorphology, without considering the impact of the denudation area, which has certain limitations, and does not consider the impact of the lithology dimension on the reservoir. It is impossible to effectively restore the ancient source during the deposition period, which greatly affects the judgment of high-quality reservoirs.

[0003] The prior art discloses a method for lithological restoration of paleo-geomorphology, which includes: S1: differential settlement correction of residual geomorphology; S2: fault restoration; S3: structural-sedimentary unit division; S4: denudation recovery; S5: correction of differential settlement of residual paleo-geomorphology and restoration of denudation, perfecting the restoration of paleo-geomorphology framework during the sedimentary period, stripping the denudation back to the bulge area, and superimposing the landforms of the differential settlement sedimentary area to complete the restoration of the paleo-geomorphology framework during the sedimentary period; S6: characterization of the bulge parent rock type and the distribution of the residual parent rock; S7: statistical analysis of drilling cuttings components; S8: qualitative restoration of the parent rock type and distribution in the source area during the sedimentary period. This scheme links the denudation amount and the denuded parent rock with the sedimentary material, providing a new basis for the development of favorable reservoirs.

[0004] However, the existing technology only semi-quantitatively describes the amount of erosion by restoring the denuded strata, fails to establish a balanced relationship between the amount of erosion and the sedimentation flux, and cannot quantitatively study the volume of the two. For high-precision exploration with seismic resolution in sand groups, only semi-quantitatively describing the amount of erosion cannot meet the exploration needs, and it is difficult to predict the sedimentation distribution pattern and reservoir thickness. Therefore, the existing technology has a technical problem of not being able to predict the thickness of the sedimentary sand body based on the quantitative calculation of the amount of erosion and the sedimentation flux. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiency in the prior art that there is no method for predicting the thickness of sedimentary sand bodies based on quantitative calculation of erosion amount and deposition flux, and to provide a method for predicting the thickness of sedimentary sand bodies based on quantitative calculation of erosion amount and deposition flux.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux comprises the following steps:

[0008] S1. Determine the scope of the denudation zone; determine the top interface of the target layer through well-seismic calibration, conduct seismic interpretation and tracking of the top interface in the whole area, and determine the area above the superline and fault superline of the top interface as the distribution range of the denudation zone of the target layer during the deposition period, based on the contact relationship between the top interface of the formation and the underlying formation;

[0009] S2. Identify the lithology of the parent rock as sedimentary rock, igneous rock or metamorphic rock;

[0010] 21) When the exploration level of the study area is low and there is no drilling exposure in the target layer and the denuded parent rock area, the lithology of the parent rock area is predicted by analogy with the regional tectonic evolution and the regional basement parent rock distribution;

[0011] 22) When the lithology of the target sedimentary layer is revealed by drilling, but the lithology of the denuded parent rock area is not revealed by drilling, the lithology of the parent rock area is comprehensively judged based on the rock-mineral combination and geochemical characteristics of the target layer stratigraphic layer under the premise of regional tectonic evolution analogy;

[0012] 23) When the target sedimentary strata are revealed by drilling and the lithology of the denuded parent rock area is revealed by drilling, the lithology of the parent rock area is comprehensively judged based on the combination of sedimentary strata and parent rock minerals and geochemical characteristics under the premise of regional tectonic evolution analogy;

[0013] S3. Calculate the amount of erosion in the erosion zone using the stratigraphic correlation method;

[0014] S4. Characterize the sedimentation flux of the target layer in the sedimentary area;

[0015] 41) Characterize the sedimentary bodies of the target layers in the sedimentary area;

[0016] 42) Predict the sand content of the sedimentary body in the target layer of the sedimentary area;

[0017] 43) Predict the sedimentation flux of the target layer in the sedimentation area;

[0018] S5. Predict the sand body thickness of the target layer in the sedimentary area.

[0019] The invention discloses a method for predicting the thickness of sedimentary sand bodies based on quantitative calculation of erosion amount and deposition flux. On the premise of understanding the parent rock strata and lithology of the erosion area, the overall erosion amount is calculated by restoring the eroded strata in the erosion area. Meanwhile, on the basis of well seismic calibration, the top and bottom surfaces of the sedimentary body are tracked to characterize the area and thickness of the sedimentary body. According to the development of the drilled strata and the changes of the sedimentary facies belt, a sand content model is established. The plane distribution of sandstone thickness can be obtained by multiplying the sand content by the thickness of the sedimentary body. Combined with the area of ​​the sedimentary body, the sandstone deposition flux of the sedimentary body is obtained. Finally, the relationship between the erosion amount and the deposition flux is quantitatively calculated to obtain the distribution law of the sand bodies of the sedimentary body in the area and the predicted thickness. The method realizes the transition from quantitative characterization of the erosion amount and the deposition flux to comprehensive prediction of the thickness of the sedimentary sand bodies. The prediction accuracy is high, and the evaluation of key exploration areas and the optimization of targets are effectively supported. The drilling of targets in complex areas is promoted, and good oil and gas displays are obtained through drilling. The technical problem that the thickness of sedimentary sand bodies cannot be predicted based on quantitative calculation of the erosion amount and the deposition flux in the prior art is effectively solved.

[0020] Furthermore, in step S3, if the parent rock is sedimentary rock, based on the structural evolution characteristics of the depression and the distribution of the residual stratum thickness of the sedimentary rock strata in the erosion area, the erosion volume of the sedimentary rock parent rock is obtained by stratigraphic correlation method as V 沉积岩 =S 沉积岩 *(H 地层 -H 残余地层 ), where V 沉积岩 is the amount of erosion in the sedimentary rock area, S 沉积岩 is the denudation area of ​​sedimentary rock area, H 地层 The thickness of sedimentary rocks deposited in the denudation zone estimated by stratigraphic correlation method, H 残余地层 It is the thickness of the residual strata in the sedimentary rock area. The calculation method of the erosion amount is different for different parent rock types in the erosion area. When the parent rock type is only sedimentary rock, the erosion amount is calculated based on the lithology of the sedimentary rock.

[0021] Furthermore, in step S3, if the parent rock is igneous rock or metamorphic rock, the denudation volume of the corresponding igneous rock or metamorphic rock parent rock is V 火成岩(或变质岩) =S 火成岩(或变质岩) *K 火成岩(或变质岩) *T, where V 火成岩(或变质岩) is the amount of erosion in igneous or metamorphic rock areas, K 火成岩(或变质岩) is the erosion rate of igneous or metamorphic rock, S 沉积岩 is the denudation area of ​​the sedimentary rock area, and T is the denudation exposure time. When the parent rock type is only igneous rock or metamorphic rock, the denudation amount is calculated based on the lithology of igneous rock or metamorphic rock.

[0022] Furthermore, in step S3, if the parent rock is a sedimentary rock, an igneous rock or a metamorphic rock, the erosion amount of each type of rock is calculated separately, and then the overall erosion amount V of the erosion area is obtained. 总 =V沉积岩 +V 火成岩或变质岩 When the parent rock types include sedimentary rock, igneous rock or metamorphic rock, it is necessary to calculate the sum of the denudation amount corresponding to different parent rock areas.

[0023] Furthermore, when only the contribution of the denudation area to the denudation amount is considered, the denudation amount received by the target layer is Where V 剥蚀 is the amount of erosion received by the target layer, V 总 is the total amount of erosion in the erosion zone, S 1 is the area of ​​the denudation zone during the deposition period of the target layer, and Si is the area of ​​the denudation zone corresponding to the denudation amount allocated to different deposition periods. The area of ​​the denudation zone is the main factor affecting the amount of denudation, and the amount of denudation is positively correlated with the area of ​​the denudation zone. The proportion of the total denudation amount allocated to the strata in different deposition periods is allocated according to the area of ​​the denudation zone in the corresponding deposition period. On the basis of seismic stratigraphic interpretation and tracking, the scope of the denudation zone in each deposition period is determined.

[0024] Furthermore, the sand content of the strata encountered by the wells in the study area was statistically analyzed, and the average sand content of the wells was calculated by strata, so that the average sand content of the strata in each deposition period that received erosion was P1, P2...Pn. The erosion amount received by the target stratum is Where V 剥蚀 is the amount of erosion received by the target layer, V 总 is the total amount of erosion in the erosion area, P 1 is the average sand content of the target layer during the deposition period, and Si is the average sand content of the formation corresponding to the denudation amount in the denudation area allocated to different deposition periods. The average sand content ratio of the formation encountered by the drilled well objectively reflects the development characteristics of the formation in the study area, and thus can reflect the total amount of sedimentation received by the layer to a certain extent.

[0025] Further, the specific steps of step 41) are: determine the seismic phase, reflection feature tracking and attribute distribution characteristics of the sedimentary area through the well seismic calibration of the drilled well, and respectively implement the top interface H of the sedimentary body tracked in the seismic work area 沉积体顶 and the sediment bottom interface H 沉积体底 The distribution of sediments is determined by the distribution range and distribution area S 沉积体 , and then the volume of the sediment is V 沉积体 =S 沉积体 *(H 沉积体底 -H 沉积体顶 ); At the same time, the plane thickness distribution of the deposited body is obtained as H 沉积体 =H 沉积体底 -H 沉积体顶 .

[0026] Further, the specific steps of step 42) are: according to the sand content of the sedimentary body that has been drilled, combined with the development law of the sedimentary body phase belt, the thickness of the sedimentary body and the distance from the source and the deposition center of the sedimentary body, the plane model of the sand content of the sedimentary body is established by using interpolation software, and the plane distribution of the sand content of the sedimentary body is obtained as P 沉积体 .

[0027] Further, the specific steps of step 43) are: based on the volume of the sediment body and the distribution of the sand content of the sediment body, the sediment flux is predicted to obtain V 沉积通量 =V 沉积体 *P 沉积体 , where V 沉积通量 is the sedimentation flux of the sedimentary sand body in the sedimentary area, V 沉积体 is the volume of the sediment, P 沉积体 is the planar distribution of the sand content of the sediment.

[0028] Furthermore, the specific steps of step S5 are: if V 剥蚀 <V 沉积 , indicating that the amount of erosion in the erosion area does not meet the material supply required by the sedimentary area, and the prediction of the sand body thickness in the sedimentary area is not accurate; if V 剥蚀 >V 沉积通量 , indicating that the erosion amount in the erosion area meets the material supply required by the sedimentary area, and the sand body prediction in the sedimentary area is within a reasonable range; on this basis, according to the thickness of the sedimentary body and the plane distribution of the sand content of the sedimentary body, the plane distribution of the sand body thickness of the sedimentary body is predicted, and H 砂体 =H 沉积体 *P 沉积体 , H 砂体 is the planar distribution of the sedimentary sand body thickness, H 沉积体 is the planar distribution of the thickness of the sediment, P 沉积体 It is the planar distribution of sand content in the sediment.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The method of the present invention is a method for predicting the thickness of sedimentary sand bodies based on quantitative calculation of erosion amount and deposition flux. By quantitatively calculating the size relationship between the erosion amount and the deposition flux, the distribution law of the sedimentary sand body and the predicted thickness are obtained, and the quantitative characterization of the erosion amount and the deposition flux is realized to the comprehensive prediction of the thickness of the sedimentary sand body. The prediction accuracy is high, and it effectively supports the evaluation of key exploration areas and the optimization of targets, promotes the drilling of targets in complex areas, and obtains good oil and gas displays through drilling, which effectively solves the technical problem that there is no method for predicting the thickness of sedimentary sand bodies based on quantitative calculation of erosion amount and deposition flux in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1A flowchart of a method for predicting the thickness of sedimentary sand bodies based on quantitative calculation of erosion and deposition flux;

[0032] Figure 2 is the thickness map of the delta envelope;

[0033] Figure 3 This is the prediction map of the sand content in the delta;

[0034] Figure 4 This is the predicted thickness map of deltaic sandstone. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0036] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] Embodiment 1

[0038] like Figure 1 The figure shows the first embodiment of a method for predicting the thickness of a sedimentary sand body based on quantitative calculation of the amount of erosion and the deposition flux according to the present invention.

[0039] A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux comprises the following steps:

[0040] S1. Determine the scope of the denudation zone; determine the top interface of the target layer through well-seismic calibration, conduct seismic interpretation and tracking of the top interface in the whole area, and determine the area above the superline and fault superline of the top interface as the distribution range of the denudation zone of the target layer during the deposition period, based on the contact relationship between the top interface of the formation and the underlying formation;

[0041] S2. Identify the lithology of the parent rock as sedimentary rock, igneous rock or metamorphic rock;

[0042] 21) When the exploration level of the study area is low and there is no drilling exposure in the target layer and the denuded parent rock area, the lithology of the parent rock area is predicted by analogy with the regional tectonic evolution and the regional basement parent rock distribution;

[0043] 22) When the lithology of the target sedimentary layer is revealed by drilling, but the lithology of the denuded parent rock area is not revealed by drilling, the lithology of the parent rock area is comprehensively judged based on the rock-mineral combination and geochemical characteristics of the target layer stratigraphic layer under the premise of regional tectonic evolution analogy;

[0044] 23) When the target sedimentary strata are revealed by drilling and the lithology of the denuded parent rock area is revealed by drilling, the lithology of the parent rock area is comprehensively judged based on the combination of sedimentary strata and parent rock minerals and geochemical characteristics under the premise of regional tectonic evolution analogy;

[0045] S3. Calculate the amount of erosion in the erosion zone using the stratigraphic correlation method;

[0046] S4. Characterize the sedimentation flux of the target layer section in the sedimentation area;

[0047] 41) Characterize the sedimentary bodies of the target layers in the sedimentary area;

[0048] 42) Predict the sand content of the sedimentary body in the target layer of the sedimentary area;

[0049] 43) Predict the sedimentation flux of the target layer in the sedimentation area;

[0050] S5. Predict the sand body thickness of the target layer in the sedimentary area.

[0051] Among them, in step S3, if the parent rock is sedimentary rock, based on the structural evolution characteristics of the depression and the distribution of the residual stratum thickness of the sedimentary rock strata in the erosion area, the erosion volume of the sedimentary rock parent rock is obtained by the stratigraphic correlation method as V 沉积岩 =S 沉积岩 *(H 地层 -H 残余地层 ), where V 沉积岩 is the amount of erosion in the sedimentary rock area, S 沉积岩 is the denudation area of ​​sedimentary rock area, H 地层 The thickness of sedimentary rocks deposited in the denudation zone estimated by stratigraphic correlation method, H 残余地层 is the current residual stratum thickness in the sedimentary rock area. In step S3, if the parent rock is igneous rock or metamorphic rock, the denudation volume of the corresponding igneous rock or metamorphic rock parent rock is V 火成岩(或变质岩) =S 火成岩(或变质岩) *K 火成岩(或变质岩) *T, where V 火成岩(或变质岩) is the amount of erosion in igneous or metamorphic rock areas, K 火成岩(或变质岩) is the erosion rate of igneous or metamorphic rock, S 沉积岩is the denudation area of ​​the sedimentary rock area, and T is the denudation exposure time. In step S3, if the parent rock is a sedimentary rock, an igneous rock, or a metamorphic rock, the denudation amount of each type of rock is calculated separately, and then the total denudation amount V of the denudation area is obtained. 总 =V 沉积岩 +V 火成岩或变质岩 .

[0052] In this embodiment, if Figure 1 As shown in the figure, on the premise of understanding the parent rock strata and lithology of the denuded area, the overall denudation amount is calculated by restoring the denuded strata in the denuded area; at the same time, on the basis of well seismic calibration, the top and bottom surfaces of the sedimentary body are tracked, the area and thickness of the sedimentary body are characterized, and a sand content model is established according to the development of the drilled strata and the changes in the sedimentary facies. The plane distribution of sandstone thickness can be obtained by multiplying the sand content by the thickness of the sedimentary body. Combined with the area of ​​the sedimentary body, the sandstone deposition flux of the sedimentary body is obtained, and finally the relationship between the denudation amount and the deposition flux is quantitatively calculated, and the distribution law and predicted thickness of the sedimentary sand body in the area are obtained, which realizes the transition from quantitative characterization of denudation amount and deposition flux to comprehensive prediction of sedimentary sand body thickness. The prediction accuracy is high, which effectively supports the evaluation of key exploration areas and target optimization, promotes the drilling of targets in complex areas, and obtains good oil and gas displays through drilling, effectively solving the technical problem that there is no method to predict the thickness of sedimentary sand bodies based on quantitative calculation of denudation amount and deposition flux in the prior art.

[0053] In this embodiment, the calculation method of the erosion amount is different for different parent rock types in the erosion area. When the parent rock type is only sedimentary rock, the erosion amount is calculated based on the lithology of the sedimentary rock; when the parent rock type is only igneous rock or metamorphic rock, the erosion amount is calculated based on the lithology of the igneous rock or metamorphic rock; when the parent rock type includes multiple lithologies of sedimentary rock, igneous rock or metamorphic rock, it is necessary to calculate the sum of the erosion amounts corresponding to different parent rock areas separately.

[0054] Embodiment 2

[0055] This embodiment is the second embodiment of the method for predicting the thickness of a sedimentary sand body based on quantitative calculation of the amount of erosion and the deposition flux of the present invention.

[0056] This embodiment is similar to the first embodiment, except that: based on seismic interpretation, through the analysis of stratum contact relationship (fault, overlap, truncation, overlap), the denudation area and stratum development characteristics are comprehensively considered, and two different schemes are used to calculate the denudation amount received by the target layer segment. The first method is to only consider the contribution of the denudation area to the denudation amount. The denudation amount received by the target layer segment is Where V 剥蚀 is the amount of erosion received by the target layer, V 总 is the total amount of erosion in the erosion zone, S 1is the area of ​​the denudation zone during the deposition period of the target layer, and Si is the area of ​​the denudation zone corresponding to different deposition periods. The second method is to count the sand content of the strata encountered by the wells in the study area, and then calculate the average sand content of the wells in the strata, so as to obtain the average sand content of the strata in each deposition period that received the denudation amount, which is P1, P2...Pn. Then the denudation amount received by the target layer is Where V 剥蚀 is the amount of erosion received by the target layer, V 总 is the total amount of erosion in the erosion zone, P 1 is the average sand content of the target layer during the deposition period, and Si is the average sand content of the strata corresponding to the denudation amount in the denudation zone allocated to different deposition periods.

[0057] In this embodiment, the area of ​​the denudation zone is the main factor affecting the amount of denudation, and the amount of denudation is positively correlated with the area of ​​the denudation zone. The proportion of the total amount of denudation allocated to strata in different sedimentary periods is allocated according to the area of ​​the denudation zone in the corresponding sedimentary period. Based on the interpretation and tracking of seismic stratigraphic positions, the scope of the denudation zone in each sedimentary period is determined.

[0058] In this embodiment, the average sand content ratio of the strata encountered by the drilled wells objectively reflects the development characteristics of the strata in the study area, and thus can reflect the total amount of sedimentation received by the stratum to a certain extent.

[0059] Embodiment 3

[0060] like Figures 2 to 4 The third embodiment of the method for predicting the thickness of a sedimentary sand body based on quantitative calculation of the erosion amount and the deposition flux according to the present invention is shown.

[0061] This embodiment is similar to the first embodiment or the second embodiment, except that: the target layer section in the sedimentary area can deposit fan delta, delta, submarine fan and other types of sedimentary bodies. Taking the delta as an example, the sedimentary flux characterization of the target layer section in the sedimentary area starts from two aspects: the characterization of the delta area, volume and thickness of the target layer section and the calculation of the thickness of the delta sand body. The corresponding reference methods are applied to other sedimentary systems.

[0062] 41) Characterize the sedimentary body of the target layer in the sedimentary area:

[0063] The seismic phase, reflection feature tracking and attribute distribution characteristics of the sedimentary area are determined by the well seismic calibration of the drilled wells, and the delta top interface H 三角洲顶 and delta bottom interface H 三角洲底 The distribution of the delta is determined by the distribution range and area S 三角洲 , and then the volume of the delta is V 三角洲 =S 三角洲 *(H 三角洲底 -H 三角洲顶); meanwhile, the planar thickness distribution of the delta is obtained as H 三角洲 = H 三角洲底 - H 三角洲顶 . The typical seismic facies and reflection characteristics of the delta show a feature of being thick in the middle and thin on both sides perpendicular to the direction of the provenance, with an obvious erosion effect on the underlying strata; along the direction of the provenance, it is controlled by multiple stepped faults and advances far into the concave. The sand body in the downthrown block of the main fault thickens, and the progradation phenomenon is obvious, etc.

[0064] 42) Predict the sand content rate of the sediment body in the target layer of the sedimentation area:

[0065] Based on the sand content rate of the drilled wells in the delta, combined with the development law of the delta facies belt, the thickness of the delta, the distance from the provenance, and the distance from the delta sedimentation center, use interpolation software to establish a planar model of the sand content rate of the delta, and obtain the planar distribution of the sand content rate of the delta as P 三角洲 . In the delta sedimentation system, the development of sand bodies has a general rule. The grain size of the delta plain near the provenance is coarser and the sand content rate is higher; the sandstone thickness at the position of the delta front in the sedimentation center is larger, and the sand content rate is higher than that in the area far from the provenance; the grain size of the delta front in the area far from the provenance is finer, the thickness is smaller, and the sand content rate is lower.

[0066] 43) Predict the sedimentation flux of the target layer in the sedimentation area:

[0067] Based on the comprehensive prediction of the sedimentation flux by combining the volume of the delta and the distribution of the sand content rate of the delta, obtain V 沉积通量 = V 三角洲 * P 三角洲 , where V 沉积通量 is the sedimentation flux of the sedimented sand body in the sedimentation area, V 三角洲 is the volume of the delta, and P 三角洲 is the planar distribution of the sand content rate of the delta.

[0068] S5. Predict the sand body thickness of the target layer in the sedimentation area:

[0069] Through the above calculations, obtain the erosion amount V 剥蚀 accepted by the target layer section and the sedimentation flux V 沉积 in the sedimentation area. If V 剥蚀 < V 沉积 , it indicates that the erosion amount in the erosion area does not meet the material supply required by the sedimentation area, and the prediction of the sand body thickness in the sedimentation area is inaccurate; if V 剥蚀 > V 沉积通量 , it indicates that the erosion amount in the erosion area meets the material supply required by the sedimentation area, and the prediction of the sand body in the sedimentation area is within a reasonable range; on this basis, according to the thickness of the delta and the planar distribution of the sand content rate of the delta, predict the planar distribution of the sand body thickness of the delta, and obtain H 砂体 = H 三角洲 * P 三角洲 , H砂体 is the planar distribution of the sedimentary sand body thickness of the delta, H 三角洲 is the plane distribution of delta thickness, P 三角洲 This is the planar distribution of the sand content in the delta.

[0070] In this embodiment, if Figures 2 to 4 As shown, the present invention can be applied to the Y area, a key exploration area of ​​the Baodao Sag in the Qiongdongnan Basin in the northern South China Sea, to address the problem of "small sources can develop large reservoirs" faced by medium and deep exploration in the northern South China Sea: the Ling III section of the Y area of ​​the Baodao Sag in the Qiongdongnan Basin in the northern South China Sea develops small uplift sources. By calculating the amount of erosion in the erosion area and the sedimentation flux in the sedimentation area, it is believed that the small uplift area has the possibility of developing a large delta. Through the characterization of the delta by seismic, combined with the distribution of sand content in the drilled wells and the distribution characteristics of the sand content in the delta, a sand content prediction model is established to predict the thickness distribution of the delta sand body and identify favorable exploration areas. Using the above method, it is calculated that the amount of erosion received by the Ling III section during the high period is about 22km 3 , the sedimentation flux is 20km 3 The average thickness of the sand body is 54m, which meets the debris supply required by the sedimentary sandstone in the area. The sand content of the W1 design well area is predicted to be 50%, and the sandstone thickness is 52.5m. The deployment of the exploration well W1 was promoted. The actual drilling sand body thickness is 59.5m, which is close to the pre-drilling prediction, and thick gas layers are discovered, achieving a breakthrough in new areas of deepwater and deep-layer exploration, and also showing good exploration prospects. The present invention realizes the quantitative characterization of erosion amount and deposition flux to the comprehensive prediction of sedimentary sand body thickness, with high prediction accuracy, effectively supporting the evaluation of key exploration areas and target optimization, promoting the drilling of targets in complex areas, and obtaining good oil and gas displays through drilling.

[0071] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for predicting the thickness of sedimentary sand bodies based on quantitative calculation of erosion and deposition flux, It is characterized in that The following steps are involved: S1. Determine the scope of the denudation zone; determine the top interface of the target layer through well-seismic calibration, conduct seismic interpretation and tracking of the top interface in the whole area, and determine the area above the superline and fault superline of the top interface as the distribution range of the denudation zone of the target layer during the deposition period, based on the contact relationship between the top interface of the formation and the underlying formation; S2. Identify the lithology of the parent rock as sedimentary rock, igneous rock or metamorphic rock; 21) When the exploration level of the study area is low and there is no drilling exposure in the target layer and the denuded parent rock area, the lithology of the parent rock area is predicted by analogy with the regional tectonic evolution and the regional basement parent rock distribution; 22) When the lithology of the target sedimentary layer is revealed by drilling, but the lithology of the denuded parent rock area is not revealed by drilling, the lithology of the parent rock area is comprehensively judged based on the rock-mineral combination and geochemical characteristics of the target layer stratigraphic layer under the premise of regional tectonic evolution analogy; 23) When the target sedimentary strata are revealed by drilling and the lithology of the denuded parent rock area is revealed by drilling, the lithology of the parent rock area is comprehensively judged based on the combination of sedimentary strata and parent rock minerals and geochemical characteristics under the premise of regional tectonic evolution analogy; S3. Calculate the amount of erosion in the erosion zone using the stratigraphic correlation method; S4. Characterize the sedimentation flux of the target layer in the sedimentary area; 41) Characterize the sedimentary bodies of the target layers in the sedimentary area; 42) Predict the sand content of the sedimentary body in the target layer of the sedimentary area; 43) Predict the sedimentation flux of the target layer in the sedimentation area; S5. Predict the sand body thickness of the target layer in the sedimentary area.

2. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux according to claim 1, Features: In step S3, if the parent rock is sedimentary rock, based on the structural evolution characteristics of the depression and the distribution of the residual stratum thickness of the sedimentary rock strata in the erosion area, the erosion volume of the sedimentary rock parent rock is obtained by stratigraphic correlation method as V 沉积岩 =S 沉积岩 *(H 地层 -H 残余地层 ), where V 沉积岩 is the amount of erosion in the sedimentary rock area, S 沉积岩 is the denudation area of ​​sedimentary rock area, H 地层 The thickness of sedimentary rocks deposited in the denudation zone estimated by stratigraphic correlation method, H 残余地层 It is the current residual stratum thickness in the sedimentary rock area.

3. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and deposition flux according to claim 2, Features: In step S3, if the parent rock is igneous rock or metamorphic rock, the denudation volume of the corresponding igneous rock or metamorphic rock parent rock is V 火成岩或变质岩 =S 火成岩或变质岩 *K 火成岩或变质岩 *T, Where V 火成岩或变质岩 is the amount of erosion in igneous or metamorphic rock areas, K 火成岩或变质岩 is the erosion rate of igneous or metamorphic rock, S 沉积岩 is the denudation area of ​​sedimentary rock area, and T is the denudation exposure time.

4. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and deposition flux according to claim 3, Features: In step S3, if the parent rock is a sedimentary rock, an igneous rock or a metamorphic rock, the erosion amount of each type of rock is calculated separately, and then the total erosion amount V of the erosion area is obtained. 总 =V 沉积岩 +V 火成岩或变质岩 .

5. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux according to claim 4, Features: When only the contribution of the denudation area to the denudation amount is considered, the denudation amount received by the target layer is Where V 剥蚀 is the amount of erosion received by the target layer, V 总 is the total amount of erosion in the erosion zone, S 1 is the area of ​​the denudation zone during the deposition period of the target layer, and Si is the denudation amount of the denudation zone allocated to the area of ​​the denudation zone corresponding to different deposition periods.

6. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and deposition flux according to claim 4, Features: The sand content of the strata encountered by the wells in the study area is statistically analyzed, and the average sand content of the wells is calculated by segment, so that the average sand content of the strata in each deposition period that receives the erosion amount is P1, P2...Pn. The erosion amount received by the target layer is Where V 剥蚀 is the amount of erosion received by the target layer, V 总 is the total amount of erosion in the erosion zone, P 1 is the average sand content of the target layer during the deposition period, and Pi is the average sand content of the strata corresponding to the denudation amount in the denudation zone allocated to different deposition periods.

7. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux according to claim 6, It is characterized in that The specific steps of step 41) are: determine the seismic phase, reflection feature tracking and attribute distribution characteristics of the sedimentary area through the well seismic calibration of the drilled well, and respectively implement the top interface H of the sedimentary body tracked in the seismic work area 沉积体顶 and the sediment bottom interface H 沉积体底 The distribution of sediments is determined by the distribution range and distribution area S 沉积体 , and then the volume of the sediment is V 沉积体 =S 沉积体 *(H 沉积体底 -H 沉积体顶 ); At the same time, the plane thickness distribution of the deposited body is obtained as H 沉积体 =H 沉积体底 -H 沉积体顶 .

8. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux according to claim 7, It is characterized in that The specific steps of step 42) are as follows: according to the sand content of the sedimentary body that has been drilled, combined with the development law of the sedimentary body phase belt, the thickness of the sedimentary body and the distance from the source and the deposition center of the sedimentary body, the plane model of the sand content of the sedimentary body is established by using interpolation software, and the plane distribution of the sand content of the sedimentary body is obtained as P 沉积体 .

9. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux according to claim 8, It is characterized in that The specific steps of step 43) are: based on the volume of the sediment body and the distribution of the sand content of the sediment body, the sediment flux is predicted to obtain V 沉积通量 =V 沉积体 *P 沉积体 , where V 沉积通量 is the sedimentation flux of the sedimentary sand body in the sedimentary area, V 沉积体 is the volume of the sediment, P 沉积体 is the planar distribution of the sand content of the sediment.

10. A method for predicting the thickness of a sedimentary sand body based on quantitative calculation of erosion amount and sedimentation flux according to claim 9, It is characterized in that The specific steps of step S5 are: if V 剥蚀 <V 沉积通量 , indicating that the erosion volume in the erosion area does not meet the material supply required by the sedimentary area, and the prediction of the sand body thickness in the sedimentary area is not accurate; if V 剥蚀 >V 沉积通量 , indicating that the erosion amount in the erosion area meets the material supply required by the sedimentary area, and the sand body prediction in the sedimentary area is within a reasonable range; on this basis, according to the thickness of the sedimentary body and the plane distribution of the sand content of the sedimentary body, the plane distribution of the sand body thickness of the sedimentary body is predicted, and H 砂体 =H 沉积体 *P 沉积体 , H 砂体 is the planar distribution of the thickness of the sedimentary sand body, H 沉积体 is the planar distribution of the thickness of the sediment, P 沉积体 It is the planar distribution of sand content in the sediment.

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