Quantitative evaluation method for lateral sealing of fault

Abstract

The invention discloses a quantitative evaluation method for lateral sealing of a fault.The method is mainly based on the research about the fault sealing mechanism and influence factors thereof, under the circumstance that pressure bearing time of the fault is considered, a fault-reservoir displacement pressure difference method for quantitative evaluation of fault sealing is improved, and a fault sealing quantitative evaluation geological and teaching model taking the time factors into consideration is established.The gradual-approximation algorithm with the given step length is adopted, it is determined that rocks of a surrounding rock stratum have the same shale content as a target spot stratum and the burial depth at the diagenetic degree, then according to the relation between the product of the shale content of the rocks built in a research area and the burial depth and the displacement pressure, the displacement pressure of target spot stratum rocks is calculated quantitatively and compared with the displacement pressure of a target disc reservoir stratum, and whether the fault is sealed or not as well as the magnitude of the sealing capability are evaluated quantitatively.It is verified through actual data that when compared with a fault rock shale content (SGR) method and the fault-reservoir displacement pressure difference fault sealing evaluation method which does not consider pressure bearing time, the method has feasibility.

Description

technical field [0001] The invention relates to a quantitative evaluation method for lateral sealing of faults applied in the field of geophysical exploration. Background technique [0002] The permeability of fault rocks determines the vertical and lateral sealing capabilities of faults. Even if the opposite face of the target reservoir is an impermeable formation, if the fault rocks are permeable, oil and gas will flow upward along the fault through the fault rocks. Therefore, the vertical and lateral sealing capabilities of faults mainly depend on the permeability of fault rocks. When studying fault sealing, at present, most researchers focus on the permeability of fault rocks, and quantitatively evaluate the vertical and lateral sealing capabilities of faults by studying the structure, shale content, diagenetic degree and other factors of fault rocks. There are mainly three existing methods for quantitative research on fault sealing based on fault rocks: (1) Indirect ev...

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Problems solved by technology

The disadvantages of this method are: ①It is only statistically significant, not based on the sealing mechanism; ②The dip angle of the fault is not considered, and the burial depth of the breakpoint is estimated according to the depth interval, so the evaluation accuracy is low; ③The data are all from the existing oil and gas reservoirs, and the established The evaluation formula can only evaluate the height of the oil and gas column that can be sealed by fault traps, and it will inevitably lead to misjudgment of faults that are not actually sealed. SGR how small the value is, H o Both are positive values, that is to say, even if the shale content of the fault rock is zero, the fault still has the sealing ability, which is obviously inconsistent with the reality

However, this method does not consider the influence of diagenetic time, and for rock formations with the same buried depth, the longer the pressure-bearing time, the higher the degree of compaction and diagenesis of the rock formation, and the worse the physical properties

Therefore, the calculation results of displacement pressure of fault rocks without considering the influence of time factors must have deviations from the actual situation

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