Multi-branch-hole finite sand control exploitation method for marine silty reservoir gas hydrates

Abstract

The invention belongs to the technical field of marine gas hydrate resource development engineering, and particularly relates to a multi-branch-hole finite sand control exploitation method for marine silty reservoir gas hydrates. The method comprises the following steps that (1) a main borehole is drilled, and a casing pipe with reserved branch holes is adopted for well completion; (2), multi-branch holes are drilled, wherein the multi-branch holes are distributed around the main borehole evenly and arranged directionally and have a certain included angle with the main borehole; (3), the periphery of the casing pipe of the main borehole and the multi-branch holes are filled with gravel layers for finite sand control; 4, well back-flushing is carried out, the well is put into production, and a step-by-step pressure reducing state starts. By means of the method, the inherent defect that a shallow hydrate reservoir is not suitable for fracturing reformation is overcome, and the problems that the permeability of a natural gas hydrate reservoir in the South China Sea is low, the comprehensive strength of the formation is low, and sand outflow is serious are solved; the method has great reference significance for increasing the duration of hydrate trial exploitation, and can promote the development of the hydrate commercial exploitation technology.

Description

technical field [0001] The invention belongs to the technical field of development engineering of marine natural gas hydrate resources, and in particular relates to a method for limited sand control mining of natural gas hydrate in marine silty reservoirs with multi-branch holes. Background technique [0002] Natural gas hydrate resource is a kind of potential energy, which has the characteristics of wide distribution and high energy density. The research on the exploitation of hydrate resource has become an international hot issue. However, the development of global hydrate resources is still in the trial mining stage in some areas, and there is still a long way to go before industrialized mining. [0003] At present, my country has accelerated the pace of research and accelerated the exploration and development of marine natural gas hydrate resources. According to the previous international trial mining experience, the depressurization method is the most effective mining ...

AI Technical Summary

Problems solved by technology

The in-situ test permeability and water flow pressure coefficient are extremely low, so only when the bottom hole pressure decreases greatly, it is possible to accelerate the expansion of the hydrate decomposition zone and increase the gas production rate; however, due to the low comprehensive strength of the reservoir, Blindly increasing the production pressure difference will not only fail to increase productivity, but may also lead to the overall collapse of the wellbore wall or the formation of a large amount of destructive sand, resulting in sand buried in the wellbore.

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