Quantitative evaluation method for lateral sealing of faults

Abstract

A quantitative evaluation method for lateral sealing of faults. Mainly based on the study of the mechanism of fault sealing and its influencing factors, the fault-reservoir displacement pressure difference method for quantitative evaluation of fault sealing is improved under the condition of considering the fault bearing time, and the quantitative evaluation of fault sealing taking into account the time factor is established. Geological and mathematical models. Using a given step size and gradually approaching algorithm, it is determined that the rocks in the surrounding strata have the same shale content and diagenetic degree as the target fault rock, and then according to the product and row of the rock shale content and burial depth established in the study area Quantitatively calculate the displacement pressure of the target fault rock, and compare it with the displacement pressure of the target wall reservoir to quantitatively evaluate whether the fault is sealed or not and the size of its sealing ability. This method has been verified by actual data, and compared with the shale content (SGR) method of fault rocks and the fault-reservoir displacement pressure difference evaluation method without considering the pressure bearing time, it is proved to be feasible.

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 ...

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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. No matter how small the SGR 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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