Gas extraction bored well and forming method

Abstract

The invention discloses a gas extraction bored well and a forming method. The bored well comprises a casing section and a sieve tube section. The casing section comprises a casing and a casing section well hole, and the sieve tube section comprises a sieve tube and a sieve tube section well hole; and the sieve tube is located in the sieve tube section well hole, the diameter of the sieve tube section well hole is larger than that of the casing section well hole, and a safety distance is reserved between the outer wall of the sieve tube and the hole wall of the sieve tube section well hole. The method includes forming the casing section well hole; placing the casing in the casing section well hole and cementing; drilling a hole right below the casing section well hole, chambering, and expanding the diameter of the drilled hole below the casing section well hole to be larger than that of the casing section well hole so as to form the sieve tube section well hole; and placing the sieve tube into the sieve tube section well hole, and reserving the safety distance between the outer wall of the sieve tube and the hole wall of the sieve tube section well hole. According to the gas extraction bored well and the forming method, a certain gas outlet channel can be reserved after the sieve tube is affected by extraction, and accordingly smooth gas extraction is ensured.

Description

technical field [0001] The invention relates to drilling technology, in particular to a gas drainage drilling and formation method. Background technique [0002] At present, in oil or coalbed gas well drilling projects, most of them adopt the method of drilling and setting casing. The basic process of the formation method of gas drainage drilling is: drilling, running casing, and then cementing, and repeating the above operations until the predetermined depth is reached. After the above process is completed, a gas drainage screen is placed under the casing, and a real gas drainage pipe is placed inside the casing to complete the entire gas drainage drilling structure. [0003] However, in the current gas drainage drilling, since the diameter of the drill bit used in the next stage of drilling needs to be smaller than the diameter of the casing placed in the previous stage, the inner diameter of the next stage of the pipe is smaller than that of the previous stage. , the "t...

AI Technical Summary

Problems solved by technology

For the gas drainage drilling formed by the existing method, according to the bottom hole video detection, it is found that when the hole depth is less than 500m, the screen pipe is seriously deformed due to the impact of mining

This is due to the fact that there are multiple screen holes arranged on the screen wall, the shear strength and compressive strength are low, and the rock strata that are easily moved and deformed after mining will be damaged, resulting in serious blockage of the screen channel, which seriously affects the normal operation of gas drainage. conduct

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