A fault identification method for tapping the potential of loft oil reservoirs

Abstract

This application provides a fault identification method for tapping into the potential of loft oil reservoirs, relating to the field of oilfield development technology. The method includes the following steps: for the target unit, determining the accuracy of high-position faults from both dynamic and static perspectives; identifying fault points; interpreting and confirming the fault plane and redefining the morphology of high-position faults; and verifying the rationality of new structures and fault identification. Verification shows that the fault identification method provided in this application can systematically and comprehensively identify high-position faults in old oilfields after entering the mid-stage of development, accurately locate the main controlling faults, and improve the accuracy of high-position fault identification. Compared with previous extrapolation methods, it can not only maximize the tapping of this type of remaining oil and achieve high production, but also drive the readjustment of the well network and increase the scale of available reserves, exhibiting characteristics of rapid results and high efficiency.

Description

Technical Field

[0001] This application relates to the field of oilfield development technology, and in particular to a fault identification method for tapping the potential of reservoirs containing attic oil. Background Technology

[0002] Attic oil refers to residual oil in the high structural regions of oil reservoirs. Based on experience from developing older oilfields, even in the later stages of development, tapping into the residual oil near faults in the high structural regions of complex fault-block reservoirs can still yield high production. However, the precise identification and interpretation of faults in the high structural regions of complex fault-block reservoirs faces challenges such as complex geological structures and poor seismic quality, leading to multiple interpretations of fault locations. If the precise identification and interpretation of the main controlling fault locations in older oilfields can be achieved, and even extrapolated from previous understandings, the potential of attic oil in the high structural regions of fault blocks can be maximized. Summary of the Invention

[0003] This application provides a fault identification method for tapping into the potential of oil reservoirs and improving the accuracy of identifying faults in high-position areas.

[0004] In an embodiment of this application, a fault identification method for tapping into the potential of attic oil reservoirs is provided, comprising the following steps:

[0005] For the target unit, determine whether the fault at the high location is accurate;

[0006] Identify breakpoints;

[0007] Explain and confirm the fault plane and redetermine the morphology of the fault in the tectonic high part.

[0008] In some embodiments of this application, determining whether the fault at a high location is accurate includes:

[0009] The accuracy of the fault in the target unit is determined from the first dynamic aspect;

[0010] The accuracy of the fault in the target unit is determined from the first static aspect.

[0011] In some embodiments of this application, determining whether the tomography of the target unit is accurate from a first dynamic perspective includes:

[0012] Perform production analysis on the target order; and / or,

[0013] Perform injection and sampling analysis on the target unit; and / or,

[0014] Energy analysis is performed on the target unit.

[0015] In some embodiments of this application, determining whether the tomography of the target unit is accurate from a first static perspective includes:

[0016] Perform seismic analysis on the target unit; and / or,

[0017] Geological analysis was performed on the target unit.

[0018] In some embodiments of this application, the identification of breakpoints includes:

[0019] Identify breakpoints using geological correlation methods; and / or,

[0020] Identify fault points using seismic data.

[0021] In some embodiments of this application, the interpretation of the fault plane and the redetermination of the morphology of the fault at the structural high point include:

[0022] Forward modeling of the wave equation corrects the interpretation of the phase axis; and / or,

[0023] Improve the interpretation of data through comparison with multiple sources; and / or,

[0024] Combined interpretation of well-seismic activity; and / or,

[0025] 3D visualization modeling explanation.

[0026] In some embodiments of this application, the interpretation of the fault plane and the redetermination of the morphology of the fault in the structural high region includes wave equation forward modeling to correct the phase axis interpretation;

[0027] The correction formula for the forward modeling of the wave equation to correct the interpretation of the phase axis includes formula (1);

[0028] Δh=Δt×1670÷1000 (1);

[0029] In formula (1), Δt is the time difference between before and after the in-phase axis is pulled down, and Δh is the difference between the actual depth and the seismic interpretation depth after the in-phase axis is pulled down;

[0030] The correction formula for the forward modeling of the wave equation to correct the interpretation of the phase axis includes formula (2);

[0031]

[0032] In some embodiments of this application, the fault identification method for tapping attic oil reservoirs further includes the following steps:

[0033] Verify the rationality of the new tectonic structures and fault identification.

[0034] In some embodiments of this application, verifying the rationality of the new structure and fault identification includes:

[0035] Examine the rationality of neotectonics and fault identification from a second dynamic perspective; and / or,

[0036] Examine the rationality of neotectonic and fault identification from a second static perspective; and / or,

[0037] The rationality of the new structure and fault identification was verified by implementing on-site oil exploration measures in the loft.

[0038] In some embodiments of this application, verifying the rationality of new structural and fault identification includes checking the rationality of new structural and fault identification from a second dynamic perspective, which includes reservoir dynamic characteristic feedback verification; and / or,

[0039] The verification of the rationality of new structures and fault identification includes checking the rationality of new structures and fault identification from a second static perspective, which includes the seismic static fault plane superposition method verification.

[0040] This application has the following beneficial effects:

[0041] The fault identification method for tapping into the potential of reservoirs with high-level faults provided in this application has been verified to systematically and comprehensively identify high-level faults in old oilfields that have entered the mid-stage of development. It can accurately locate the main control faults and improve the accuracy of identifying high-level faults. Compared with the extrapolation of previous stages, it can not only maximize the tapping of this type of remaining oil and achieve high production, but also drive the readjustment of the well network and increase the scale of available reserves. It has the characteristics of fast results and good benefits. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating the fault identification method for tapping the potential of reservoirs and identifying loft oil in this application embodiment;

[0044] Figure 2 This is a schematic diagram of the unutilized phenomenon of stratigraphic correlation faults in well Y29-1 in the embodiments of this application;

[0045] Figure 3 This is a schematic diagram comparing the differences in fault interpretation between the reinterpretation and the original fault interpretation in well Y29-1 in this application embodiment;

[0046] Figure 4 This is oil field E1f2 in one of the embodiments of this application. 3 -E1f1 oil-bearing layer fault planar superposition diagram. Detailed Implementation

[0047] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The terminology used in the embodiments section of this application is only used to explain the specific embodiments of this application and is not intended to limit this application.

[0048] like Figure 1 As shown in Embodiment 1 of this application, a fault identification method for tapping into the potential of attic oil reservoirs is provided, comprising the following steps:

[0049] For the target unit, determine whether the fault at the high location is accurate;

[0050] Identify breakpoints;

[0051] Explain and confirm the fault plane and redetermine the morphology of the fault in the tectonic high part.

[0052] In some embodiments of this Example 1, determining whether the fault at a high location is accurate includes:

[0053] The accuracy of the fault in the target unit is determined from the first dynamic aspect;

[0054] The accuracy of the fault in the target unit is determined from the first static aspect.

[0055] In some embodiments of this Example 1, determining whether the tomography of the target unit is accurate from a first dynamic perspective includes:

[0056] Perform production analysis on the target order; and / or,

[0057] Perform injection and sampling analysis on the target unit; and / or,

[0058] Energy analysis is performed on the target unit.

[0059] In some embodiments of this Example 1, determining whether the tomography of the target unit is accurate from a first static perspective includes:

[0060] Perform seismic analysis on the target unit; and / or,

[0061] Geological analysis was performed on the target unit.

[0062] In some embodiments of this Example 1, the identification of breakpoints includes:

[0063] Identify breakpoints using geological correlation methods; and / or,

[0064] Identify fault points using seismic data.

[0065] In some embodiments of this Example 1, the interpretation and determination of the fault plane and the redetermination of the morphology of the fault at the structural high point include:

[0066] Forward modeling of the wave equation corrects the interpretation of the phase axis; and / or,

[0067] Improve the interpretation of data through comparison with multiple sources; and / or,

[0068] Combined interpretation of well-seismic activity; and / or,

[0069] 3D visualization modeling explanation.

[0070] In some embodiments of this Example 1, the interpretation of the fault plane and the redetermination of the morphology of the fault in the structural high part includes wave equation forward modeling to correct the phase axis interpretation;

[0071] The correction formula for the forward modeling of the wave equation to correct the interpretation of the phase axis includes formula (1);

[0072] Δh=Δt×1670÷1000 (1);

[0073] In formula (1), Δt is the time difference between before and after the in-phase axis is pulled down, and Δh is the difference between the actual depth and the seismic interpretation depth after the in-phase axis is pulled down;

[0074] The correction formula for the forward modeling of the wave equation to correct the interpretation of the phase axis includes formula (2);

[0075]

[0076] In some embodiments of this Example 1, the verification of the rationality of the new structure and fault identification includes:

[0077] The rationality of neotectonics and fault identification is examined from a second dynamic perspective.

[0078] The rationality of neotectonic and fault identification is examined from a second static perspective.

[0079] In some embodiments of this Example 1, the checking of the rationality of new structures and fault identification from a second dynamic perspective includes reservoir dynamic characteristic feedback verification; and / or,

[0080] The examination of the rationality of new structures and fault identification from the second static perspective includes the verification of the seismic static fault plane superposition method.

[0081] In some embodiments of this Example 1, the verification of the rationality of the new structure and fault identification includes verification by implementing on-site attic oil potential tapping measures.

[0082] The fault identification method for tapping the potential of loft oil reservoirs provided in Example 1 of this application can systematically and comprehensively sort out the high-position faults in old oilfields after entering the mid-stage of development, realize the precise location of the main control fault, improve the accuracy of identifying high-position faults, and compared with the previous stage of extrapolation, it can not only maximize the tapping of this type of remaining oil and achieve high production, but also drive the readjustment of the well network of the formation, while increasing the scale of available reserves. It has the characteristics of fast results and good benefits.

[0083] In Embodiment 2 of this application, a fault identification method for tapping attic oil in an oil reservoir is provided, comprising the following steps:

[0084] Step 1) Determine if the fault in the high part is accurate; Step 2) Identify the fault elements; Step 3) Interpret and implement the fault plane, and redetermine the morphology of the fault in the high part of the structure; Step 4) Verify the rationality of the new structure and fault identification.

[0085] In some embodiments of Example 2, in step 1), for the target unit, the existence of contradictions in the fault and whether the location is reasonable and accurate are identified and judged from both dynamic and static aspects.

[0086] 1) Dynamically determine whether there is a contradiction.

[0087] Identifying dynamic contradictions mainly involves three aspects: production analysis, injection-production analysis, and energy analysis.

[0088] In analyzing the production of a single well or well group, it is crucial to identify phenomena such as reservoir-production discrepancies, significant production differences, and abnormal production from a single well. Reservoir-production discrepancies typically refer to a single layer's reserves being recovered to over 40%, resulting in a high reserve-production ratio. In such cases, it is necessary to analyze the fault location and the accuracy of the oil-water boundary. Significant production differences refer to substantial variations in well production performance, particularly in the initial or cumulative stages, under the same geological conditions, suggesting the possibility of different fault blocks or fault extension. Abnormal production from a single well indicates a high cumulative oil production compared to the reserves it controls, suggesting the potential for further reassessment of the geological structure and reserve scale.

[0089] Regarding the effectiveness of injection and production, phenomena such as injection-production contradictions and large differences in water cut among single wells should be identified. Injection-production contradictions can manifest in two ways: first, under the same geological conditions, some oil wells in the same water injection well group may not be effective, which may indicate the presence of faults; second, if there are obvious faults separating oil and water wells, but water injection is effective, it indicates that the faults should not exist.

[0090] In terms of energy, attention is focused on phenomena such as large differences in pressure drop across single wells and imbalances in regional energy supply. Large differences in pressure drop across single wells mainly manifest as significant variations in well pressure under the same conditions, such as differences in dynamic fluid levels. Differences in regional energy supply are reflected in large energy disparities within a region under the same conditions, including differences between low and high fluid volumes, or between low and high water cuts.

[0091] 2) Is the determination of fault location based on earthquake data reasonable?

[0092] (1) When the quality of earthquake data is good, there are two main phenomena to determine whether there are false interpretations in earthquake interpretation.

[0093] First, there is the illusion of wave impedance continuity. High-quality seismic data with good wave group continuity and clear fault wave patterns can effectively interpret and locate faults. However, this does not necessarily mean that the fault location is accurate. It is important to pay attention to the illusion of continuity where the phase axes appear continuous but are actually offset by one phase.

[0094] Second, there may be excessive fault offset. Some seismic data may appear to be of good quality, but in reality, there may be excessive fault offset, which could mislead the interpretation of faults and result in the actual strata encountered during drilling being significantly different from what was expected.

[0095] (2) The quality of the seismic data is poor. Determine whether the positions of the seismic interpretation cross-sectional waves and phase axes are reasonable.

[0096] Poor quality seismic data, especially with limited well data, makes accurate fault interpretation difficult and conversely suggests a higher likelihood of fault extrapolation and reconstruction. Therefore, it is necessary to assess the interpretation of seismic transect waves and phase axes.

[0097] When the transect waves are unclear, especially wide transect waves, they are often easily interpreted as a "reclining chair" type fault with a steep upper section and a gentle lower section. In reality, there may be multiple adjacent faults, and their seismic waves interfere with each other, resulting in unclear transect waves and discontinuous phase axes.

[0098] When the phase axis is unclear and the termination points are chaotic, inaccurate interpretation mainly manifests in two typical ways: First, the fault interpretation location is located at the termination point of the most continuous phase axis in the uplift disk. In early development, to avoid the risk of missing faults, most fault interpretation locations were placed at the termination points of the phase axis in the uplift disk. However, practice shows that the actual fault location is often not the termination point of the phase axis. Second, there are errors in phase axis calibration and identification. Identifying the phase axis of the target layer as being one phase above or one phase below can lead to inaccurate fault interpretation.

[0099] 3) Geologically determine whether the fault is reasonable.

[0100] Geologically, determining whether a fault is reasonable mainly involves analyzing whether there are any abnormal phenomena in the structural planes and fault planes.

[0101] (1) Abnormal distortion of structural lines may indicate the presence of faults. In the process of structural mapping, there are often distortions of contour lines on the structural map. Some of these distortions are covered by smoothing, but they are preserved due to differences in well depth and contrast. If this phenomenon differs from the overall trend of the surrounding structures, there may be faults that have not been identified.

[0102] (2) Abnormal fault dip angle and unreasonable fault elements. In structural maps and other geological maps, if the fault line is too smooth or extremely twisted, the dip angle of the upper and lower parts of the same fault is large, the fault line strike changes suddenly or does not conform to the overall fault pattern (for example, there is an arc-shaped fault in a combination of multiple parallel faults), then the fault line position elements may be unreasonable.

[0103] In some embodiments of Example 2, in step 2), based on the target unit in step 1), the various elements of the fault are identified using a fine geological-seismic comparison description method.

[0104] The method mainly uses geological comparison and well-seismic combination to conduct detailed comparative identification of fault locations, depths, fault distances, and numbers for actual drilled wells.

[0105] (1) Geological comparison method for identifying breakpoints

[0106] In actual stratigraphic correlation, it is common to encounter situations where the existence of faults and their precise locations cannot be accurately determined. For the interpretation of faults in high-altitude areas, accurately identifying the location, depth, displacement, and number of faults in actual drilled wells is particularly crucial.

[0107] Conventional methods involve comparing stratigraphic faults through isochronous correlation, isothickness correlation, and cyclic classification. In fact, most stratigraphic and fault correlations use the above-mentioned correlation methods, but inaccurate fault identification is still frequently found, leading to the failure to identify potential faults.

[0108] In this method, to further improve the accuracy of correlation, short-distance feature marking, vertical depth difference method, and lithological combination analysis are proposed to identify whether there are faults in the actual drilled wells, and to accurately identify the location, depth, displacement, fault strata, and number of faults. Short-distance feature marking involves marking auxiliary marker layers within a 25-50m range in both the correlation well and the standard well. These marker layers must be locally isochronous deposits, typically mudstone or special lithological bodies. Vertical depth difference method identifies faults based on the vertical depth differences of the same strata in adjacent wells on the hanging wall and footwall. Lithological combination correlation means that in stratigraphic correlation, the influence of sedimentary thickness should be considered, and adjacent lithological strata should be combined for overall correlation under the principle of overall similarity.

[0109] (2) Identifying breakpoints using seismic data

[0110] Identifying faults using seismic data involves recognizing faults on seismic profiles. Faults can be identified through six basic characteristics on seismic profiles: poor continuity of phase axes, local distortion or subsidence of phase axes, angular contact between phase axes, variations in the strength of phase axes, changes in wave group characteristics, and fault-plane waves. ① Discontinuity of reflected wave phase axes. This method is mainly applicable to seismic data of good quality, where the wave group relationship on both sides of the fault is relatively stable, and the characteristics of the reflecting layers are clear and can be compared laterally. This generally reflects medium and small-sized faults. ② Bifurcation, merging, distortion, and strong phase transitions of standard reflected phase axes. This generally reflects small faults. ③ Sudden increases, decreases, or disappearances of reflected phase axes, and sudden changes in wave group intervals. This often reflects large faults. Especially in extensional tectonic models, the uplifted block of a fault has few or no sedimentary strata, resulting in fewer, shallower, or even absent reflected phase axes on the seismic profile. Conversely, in the downthrown block of a fault, due to the continuous and significant subsidence of the basin, subsidence centers often form, resulting in thicker and more complete strata. Consequently, the number of reflection phase axes on the seismic profile increases significantly, and the reflection layers are complete. These types of faults are geologically early-formed, have a long period of activity, large displacement, and wide fracture bands, often playing a controlling role in the formation and development of strata thickness and structures. Examples include the Wubu and Zhenwu faults. ④ Abrupt changes in the attitude of reflection phase axes, resulting in scattered reflections or blank zones. This is due to fault displacement causing abrupt changes in the attitude of strata on both sides, and the shielding effect of the fault causing distortion of reflected wave rays below the fault plane. ⑤ The appearance of special waves is an important indicator for fault identification. At the point of fault displacement, fault-plane waves and diffracted waves often appear.

[0111] In some embodiments of Example 2, in step 3), based on the target unit in step 1), by re-identifying the various elements of the fault, and through multiple methods such as the wave equation, the morphology of the fault in the structural high part is re-determined.

[0112] (1) Interpretation of the wave equation by forward modeling and correction of the phase axis.

[0113] In seismic data, there are often mismatches between the phase axis and the actual drilled stratigraphic level, creating the illusion of a downward pull on the phase axis. An observation system is established based on actual data, and field blasting is simulated using wave equations to simulate seismic data and processing. Through denoising, deconvolution, and static correction, interference phenomena such as diffraction and multiples are eliminated, further improving data quality. Then, a migration velocity field is established, and the final forward modeling profile is obtained through Koschkhov pre-stack time migration.

[0114] Forward modeling analysis revealed that, with a fixed horizontal distance, a steeper fault, a thicker intermediate layer, and a greater pull-down amplitude are associated with a greater fault displacement and a greater velocity difference between the two fault plates, resulting in a greater pull-down amplitude. Any factor that increases the velocity difference between the two fault plates will enhance the fault's influence on the footwall structure. The correction formula is as follows:

[0115] Δt=161×(1 / 1260-1 / 1400)×1000=12.8(ms)

[0116] Δh=12.8×1670÷1000=21.4(m)

[0117] Δt — the time difference between when the in-phase shaft is not pulled down and when it is pulled down;

[0118] Δh — the difference between the actual depth and the seismic interpretation depth after the phase axis is pulled down.

[0119] (2) Improved interpretation of data and comparison with multiple data

[0120] Due to the influence of different data acquisition instruments, acquisition methods, and processing techniques used in different years, the overall appearance, signal-to-noise ratio, and resolution of the data vary greatly. Utilizing these differences, aspects with clear reflections from different data sources are selected for interpretation, and cross-referencing is performed to determine the fault location.

[0121] Post-stack filtering techniques can be used to remove various types of noise detrimental to seismic imaging, improve the identification of fault edges, and retain seismic reflection signals that are beneficial for tectonic interpretation. The principle is to perform spectral analysis on time-domain seismic data through Fourier transform, setting it as a finite-length sequence of N points. Its forward transform (DFT) is then:

[0122]

[0123] In the formula, k = 0, 1, 2, ..., N-1; W N =e -j2*π / N

[0124] x(n) — discrete signal, x(k) — spectrum of discrete signal;

[0125] n—the sequence number of the discrete signal, k—the sequence number of the discrete signal spectrum, N—the total length of the discrete sequence.

[0126] Fourier transform can be used to determine the bandwidth and dominant frequency information of seismic data. By analyzing the spectrum of seismic data before and after filtering, the quality of seismic data processing can be determined, and the frequency bands that improve fault imaging can be identified.

[0127] (3) Interpretation of well-seismic combination

[0128] In seismic tectonic interpretation, the stratigraphic level follows the isochronous closure interpretation based on the same phase axis. Generally, no faults are opened if there is no obvious faulting. However, actual drilling has confirmed the existence of the phenomenon of "continuous fault wave in the stratigraphic level". In this case, the interpretation should be combined with geological understanding and well-seismic analysis.

[0129] The presence of fault sectional waves (or differences in in-phase axial wave groups) in the actual drilling trajectory can assist in the determination. Generally, the above two methods can solve the determination of the existence of fault points in most cases. However, there are also situations where the seismic data is unclear or stratigraphic correlation is difficult to effectively determine whether a fault point exists. If the fault point cannot be confirmed by conventional methods, it is assumed that there is no fault and structural interpretation continues.

[0130] (4) Three-dimensional visualization modeling interpretation to determine fault morphology

[0131] Three-dimensional geological visualization and structural modeling are used to determine the morphology of faults in three-dimensional space. The essence of reservoir geological modeling is to analyze various reliable raw data and use three-dimensional graphics methods to establish a stratigraphic framework model and layered solid model of the oil and gas reservoir, providing a basis for development decisions. Structural modeling consists of fault modeling and bedding plane modeling.

[0132] Firstly, cross-section modeling aims to realize the morphology of fault points and cross sections in a 3D model. This requires preparing seismic interpretation layer data and wellbore fault point data for geological correlation. Wellbore fault points are considered source data; the cross sections formed in 3D space must pass through these fault points. Seismic interpretation data is used as soft data to constrain the macroscopic morphology of the cross sections. Combining these two methods, a reliable cross-section model is formed in 3D space.

[0133] Secondly, the goal of layer modeling is to realize the morphology of the strata in a three-dimensional model. Using detailed and verified surface layer depth data as source data and seismically interpreted stratigraphic data as soft data to constrain the macroscopic morphology, geostatistical methods are used to simulate and establish the depth distribution, strike, dip, and dip angle of each sub-layer in three-dimensional space.

[0134] Finally, by using the intersection of fault models and structural layer models in three-dimensional space, the extent of each layer is determined, and the intersection of faults at each layer is depicted; thus, the morphology of faults in structural high areas is finally determined.

[0135] In some embodiments of Example 2, in step 4), based on the target unit in step 1), the morphology of the fault in the high structural part is redefined, and the rationality of the new structure and fault understanding is checked by multiple means such as dynamic and static methods, and verified by the on-site implementation of "attic oil" potential tapping measures.

[0136] (1) Feedback verification of reservoir dynamic characteristics

[0137] When seismic data quality is poor, fault interpretation can be ambiguous. Later, the rationality of the structural interpretation is assessed based on feedback from the production dynamics of drilled wells. After a period of extraction, it is crucial to determine whether the water cut matches initial expectations and whether the cumulative production aligns with geological reserves.

[0138] (2) Seismic static fault plane superposition test

[0139] The interpretation scheme of a fault on a seismic profile is ultimately reflected in its planar combination characteristics. By superimposing fault lines at different layers of the same fault, the variation pattern of the fault from deep to shallow can be found, thereby judging the correctness of the fault interpretation and verifying the rationality of the fault scheme.

[0140] (3) Actual drilling measures verification

[0141] Based on the understanding of the new faults, "attic oil" potential is tapped through on-site drilling to verify the rationality of the new fault scheme. Actual drilling is the most direct way to verify the rationality of the new structure and fault.

[0142] The fault identification method for tapping the potential of loft oil reservoirs provided in Example 2 of this application can systematically and comprehensively sort out the high-position faults in old oilfields after entering the mid-stage of development, realize the precise location of the main control fault, improve the accuracy of identifying high-position faults, and compared with the previous stage of extrapolation, it can not only maximize the tapping of this type of remaining oil and achieve high production, but also drive the readjustment of the well network of the formation, while increasing the scale of available reserves. It has the characteristics of fast results and good benefits.

[0143] In Embodiment 3 of this application, a fault identification method for tapping attic oil in an oil reservoir is provided, comprising the following steps:

[0144] Step 1): For the target unit, determine the accuracy of the fault location at the high position based on both dynamic and static analysis. Y Oilfield was discovered and developed in the 1990s, with proven reserves of 5.99 million tons. It has multiple oil-bearing strata, long oil-bearing sections, and a relatively simple geological structure. In 2018, dynamic analysis, seismic and geological re-examinations were conducted on Y Oilfield, which had entered the later stages of development. Several anomalies were found near the high position of the fault. First, some wells at the high position had high production, indicating abnormal reserves and production. Second, the vertical distance between the fault point of nearby wells and the main oil-bearing target strata was large, and the fault point above the well was close to the underlying main oil-bearing strata E1f1. 3 The vertical distance exceeds 100m; thirdly, the seismic waves exhibit a continuity illusion, Y29-1 well E1f1 3 The interpretation of the phase axis of the stratigraphy exhibits phenomena such as back dip and pull-down, and the interpretation of faults involves shearing the strong axis. Figure 2 ).

[0145] Step 2), based on the target unit in Step 1), accurately identify the location, depth, displacement, and number of faults in the drilled wells at high locations. Regarding the anomalies found near the high locations of faults in the Y oilfield, the seismic geological comparison identification method is used, mainly including: First, using the short-distance feature marking method to conduct detailed stratigraphic comparison of the entire well at high locations, re-examine and re-divide faults, and review old well trajectories, focusing on confirming the accurate depth and number of well faults, and unifying the isochronous lines of small layers to correct sand body comparison misalignments; Second, identifying the E1f1 fault in well Y29-1 through seismic combined with geological stratification analysis. 3 The distortion of the seismic phase axis at different strata is not due to fault influence but rather a downward pull illusion.

[0146] In step 3), based on the re-identification of fault elements in step 2), the structural layer and fault plane are comprehensively interpreted and determined through various methods such as the wave equation, and the morphology of the fault in the structural high part is re-determined.

[0147] First, forward modeling of the wave equation corrects the interpretation of the phase axis, determining E1f1 in well Y29-1. 3 The interpretation of the layer as it ascends creates an angle with the phase axis. Therefore, the layer should extend at the same angle from the lower to the higher layers, not downwards through the middle of the phase axis, thus resolving the illusion problem. Figure 3 Second, a comparison of old and new data was conducted to fully examine the differences in interpretation between different data, and a comprehensive well-seismic analysis was performed to match and interpret the data. Third, fault models and structural models were determined using three-dimensional modeling, and their positions in three-dimensional space were determined. Through intersection and combination, the morphology of faults in structurally high areas was determined. After reinterpretation, the main controlling fault of this block was extrapolated, with the main stratigraphic system E1f1... 3 The fault is extrapolated by an average of 50m. The location of the main controlling fault in the Y29-1 well area is extrapolated by 100m from the original interpretation fault location. Figure 3 ).

[0148] In step 4), based on the morphology of the fault in the high structural part determined in step 3), the rationality of the new structure and fault understanding is verified, thereby implementing the "attic oil" potential tapping.

[0149] First, the production dynamics of drilled wells are dynamically matched with the reservoir and production interpretation of new structures. Second, using the fault plane superposition method, the fault interpretation is smooth and consistent across the upper and lower oil-bearing strata, indicating a reasonable interpretation. Figure 4 ),exist Figure 4 In the equation, curve a is E1f2. 3 Curve b is E1f1 1 Curve c is E1f1 2 The curve d is E1f1 3 Curve e is E1f1 4 The curve f is E1f1 5 .

[0150] Based on the re-determination of the fault morphology in the high-position area of ​​the Y oilfield, the successful drilling of well Y56 in the eastern high-position area verified the understanding of the E1f1 high-position fault extrapolation. Subsequently, a study on local adjustment schemes was conducted. From 2019 to 2021, a total of 13 high-position expansion wells were drilled, all of which were successful. On average, each well encountered 5.7 oil-bearing layers (22.6m) and 6 water-flooded layers (28.5m). After commissioning, production capacity was high, with an initial average daily oil production of 4.9t / d, and a cumulative increase in utilized geological reserves of 64.7 × 10⁻⁶. 4 t, the cumulative oil increase of new wells is 1.4×10 4 This is expected to increase the recovery rate by 3%.

[0151] In this application, "new construction" refers to the redefined construction.

[0152] In the description of the embodiments of this application, it should be noted that the terms "the above embodiments," "some embodiments," "the above implementation methods," "some implementation methods," "possible embodiments," or "possible implementation methods," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0153] In the description of the embodiments of this application, it should be noted that "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship. Terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0154] In the description of the embodiments of this application, it should be noted that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. Unless otherwise stated, "multiple" means two or more.

[0155] The above embodiments are merely explanations of this application and are not intended to limit it. After reading this specification, those skilled in the art can make modifications to the implementation methods of this application without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for fault identification in tapping the potential of attic oil reservoirs, characterized in that, Includes the following steps: For the target unit, determine whether the fault at the high location is accurate; Identify breakpoints; Explain and confirm the fault plane and redetermine the morphology of faults in the tectonic high region; The determination of whether a fault in a high location is accurate includes: The accuracy of the fault in the target unit is determined from the first dynamic aspect; The accuracy of the tortuosity of the target unit is determined from a first static perspective; The determination of whether the fault of the target unit is accurate from the first dynamic aspect includes: Perform production analysis on the target order; and / or, Perform injection and sampling analysis on the target unit; and / or, Perform energy analysis on the target unit; The determination of whether the tomography of the target unit is accurate from the first static aspect includes: Perform seismic analysis on the target unit; and / or, Geological analysis was performed on the target unit; The identified breakpoints include: Identify breakpoints using geological correlation methods; and / or, Identifying breakpoints using seismic data; The interpretation of the fault plane and the redetering of the morphology of the fault in the structural high region include: Forward modeling of the wave equation corrects the interpretation of the phase axis; and / or, Improve the interpretation of data and comparative analysis with multiple data sources; and / or, Combined interpretation of well and seismic activity; and / or, 3D visualization modeling explanation.

2. The fault identification method for tapping attic oil reservoir potential according to claim 1, characterized in that, The interpretation of the fault plane and the redetering of the morphology of the fault in the high structural region include wave equation forward modeling and correction of the phase axis interpretation. The correction formulas for the forward modeling of the wave equation to correct the interpretation of the phase axis include formula (1) and formula (2). （2）； （1）； In formula (1), ∆t is the time difference between before and after the in-phase axis is pulled down, and ∆h is the difference between the actual depth and the seismic interpretation depth after the in-phase axis is pulled down.

3. The fault identification method for tapping the potential of attic oil reservoirs according to claim 1, characterized in that, The fault identification method for tapping the potential of attic oil reservoirs also includes the following steps: Verify the rationality of the new tectonic structures and fault identification.

4. The fault identification method for tapping attic oil reservoirs according to claim 3, characterized in that, The verification of the rationality of the new structure and fault identification includes: Examine the rationality of neotectonics and fault identification from a second dynamic perspective; and / or, Examine the rationality of neotectonic and fault identification from a second static perspective; and / or, The rationality of the new structure and fault identification was verified by implementing on-site oil exploration measures in the loft.

5. The fault identification method for tapping the potential of attic oil reservoirs according to claim 3, characterized in that, The verification of the rationality of new structures and fault identification includes checking the rationality of new structures and fault identification from a second dynamic perspective, which includes reservoir dynamic characteristic feedback verification. And / or, The verification of the rationality of new structures and fault identification includes checking the rationality of new structures and fault identification from a second static perspective, which includes the seismic static fault plane superposition method verification.

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