Limited sand control mining method of multi-branched holes for natural gas hydrate in marine silty reservoirs

Abstract

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. It includes the following steps: (1) drilling the main wellbore and completing the well with reserved branch hole casing; (2) drilling multi-branch holes, which are evenly distributed around the main wellbore and form a certain angle with the main wellbore and directional arrangement; (3) Packing gravel layers around the casing of the main wellbore and in the multi-branch holes for limited sand control; (4) Backwash the well, put it into production, and enter the step-by-step depressurization stage. This method overcomes the "congenital" weakness that shallow hydrate reservoirs are not suitable for fracturing, and effectively solves the gap between the extremely low permeability of gas hydrate reservoirs in the South my country Sea, low comprehensive strength of formations, and serious sand production tendency. It has important reference significance for increasing the duration of hydrate trial production and promoting the development of hydrate commercial production 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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