A segmented horizontal well thermal co 2 Huff and puff mining method of heterogeneous gas hydrate reservoir

Abstract

The invention discloses a method for mining a heterogeneous hydrate reservoir through heat CO2 injection of a sectioned horizontal well. The method mainly comprises the steps that the horizontal production well is dug, the number and specific positions of sections are determined through conventional heat CO2 injection, then tubing columns of the horizontal production well is replaced, and the injection speeds of the tubing columns of the sections are controlled cooperatively, specifically, the horizontal production well is dug in the heterogeneous hydrate reservoir, heat CO2 is injected for injection production by two to four cycles, the temperature distributions of the horizontal well sections after the cycles are ended are recorded, the number and specific positions of the horizontal well sections are determined through an optimal partition algorithm for ordered samples, redesign is performed according to a calculation result, the tubing columns of the horizontal production well are replaced, reasonable input of the heat CO2 is ensured by adjusting the injection-production parameters of the tubing columns of the sections, and the heterogeneous hydrate reservoir is mined in an throughput mode. The method is simple in equipment, convenient to implement and capable of providing a guidance for implementation of production increase measures of the heterogeneous hydrate reservoir.

Description

technical field [0001] The invention relates to a method for mining natural gas hydrate, in particular to drilling a segmented horizontal well in a heterogeneous gas hydrate reservoir to cooperatively control the thermal CO of each segmented string. 2 The method of increasing the recovery rate of gas hydrates by using the injection rate and performing huff and puff production. Background technique [0002] Natural gas hydrate exists stably in the high temperature and low pressure environment in solid form. It has large reserves and high energy density, and is an important new energy source. With the development of society and economy, gas hydrate has attracted widespread attention, and the study of effective extraction methods is of great significance for the commercial development of gas hydrate. [0003] At present, natural gas hydrates are exploited mainly by destroying their phase equilibrium conditions, so that solid natural gas hydrates are decomposed into gaseous nat...

AI Technical Summary

Problems solved by technology

However, the use of a single mining method for development and utilization has limited effects and has many disadvantages, such as the decompression method is likely to cause the secondary formation of hydrates to block the flow channel; the thermal excitation method has a large heat loss; CO 2 The utilization efficiency of the replacement method is low

On the other hand, heterogeneity is ubiquitous in hydrate reservoirs. For hydrate reservoirs with strong heterogeneity, the degree of hydrate acceptance in high-permeability areas and low-permeability areas is significantly different, which significantly affects the development of hydrate reservoirs. Effect

[0004] At present, there are not many studies on the combination of multiple methods to develop hydrate reservoirs, and there is no effective mining method for heterogeneous hydrate reservoirs, which largely restricts the development and utilization of hydrate reservoirs

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