Geological evaluation method for fracture network transformation capacity of marine shale gas reservoir

Abstract

The invention discloses a geological evaluation method for the fracture network transformation capacity of a marine facies shale gas reservoir. The geological evaluation method comprises the followingsteps: collecting geological data of the marine facies shale gas reservoir; establishing a geological evaluation index sequence of the reservoir fracture network transformation capability, wherein the geological evaluation index sequence comprises a mineral ductility resistance index, a rock elastoplasticity index, a fracture networking index and a reservoir physical property index; calculating the weight of the reservoir fracture network reconstruction capability geological evaluation index; and a geological evaluation matrix of the fracture network transformation capacity is established, and the larger the result of the geological evaluation matrix is, the more beneficial to reservoir fracture network transformation is. According to the method, characterization parameters among influence factors do not influence each other and do not conflict with each other, the data arrangement and calculation time is saved, the evaluation accuracy is ensured, the method is convenient to master inthe actual application process, the method is suitable for indoor researchers and field technicians to quickly obtain results, the complexity is simplified, and the fracturing parameters can be optimized.

Description

technical field [0001] The invention relates to the technical field of unconventional oil and gas stimulation technology, in particular to a geological evaluation method for the fracture network stimulation ability of marine shale gas reservoirs. Background technique [0002] Reservoir evaluation is an important link in the process of shale gas exploration and development, and it is mainly used to optimize the target window sweet spot. The evaluation indicators of shale gas reservoirs are diversified, including differential structure of mineral components, development characteristics of natural weak planes, mechanical properties of rocks and fractures, ancient and modern burial depths, thermal evolution degree and organic matter abundance, porosity and Geological factors such as pore shape, magnitude and difference of in-situ stress. The conceptual evaluation of shale gas production areas can be realized by superposition of brittle mineral content; the three-dimensional des...

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Problems solved by technology

However, it can be seen from different methods that scholars have different understandings of reservoir evaluation, which also makes the existing evaluation theories and methods still have room for improvement, which is reflected in: ① Invention of CN201610191202.8, CN201510094413.5, CN201410641815.8 For example, the evaluation ideas are not uniform, multi-factor evaluation indicators are complicated, and the interaction between the indicators is not considered. For example, the increase of siliceous mineral content does not completely increase the brittleness, and the increase of porosity and organic matter content increases the storage capacity. , but reduces the mechanical strength of the rock, etc. Too many natural fractures will affect the difficulty of adding sand, etc., resulting in different opinions and conclusions in different evaluation results; ② Some evaluations believe that construction parameters are evaluation indicators, but evaluation indicators are not Engineering parameters, but geological parameters that reflect the adaptability of engineering parameters, currently rarely include geological evaluation indicators that reflect the adaptability of reservoirs to construction parameters; ③ It is not clear whether the final evaluation goal is effective fracturing or stimulation; ④ Invention CN201910688867. 3 as an example, the calculation steps are too complicated, and it is difficult to quickly identify and optimize in mine practice; ⑤Taking the inventions CN201610537793.X and CN110163533A as examples, both failed to consider the weights between various factors, even if the weights are considered, only the influence of each factor is considered the degree is equal

[0003] The southern Sichuan region is the main area for shale gas development in my country. As the gas-producing zone transitions from 2500-3000m to 3000-3500m in the construction-production area, hydraulic fracturing is faced with increased closure stress and horizontal stress differences. Natural fractures and bedding The characteristics of increasing difficulty in characterization, and the average annual single well production has decreased in recent years, indicating that the existing evaluation methods are no longer suitable for geological characteristics and actual needs

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