Separate injection string

Abstract

The invention relates to a separate injection string. The separate injection string comprises an outer pipe and an inner pipe located in the outer pipe, a ring cavity used for conducting water injection on the upper formation is formed between the inner pipe and the outer pipe, a bottom injection channel is arranged on the outer pipe, a seal structure separating the bottom injection channel from the ring cavity is arranged between the inner pipe and the outer pipe, a movable valve element used for controlling on and off of the bottom injection channel is movably assembled on the portion, at the bottom injection channel, of the outer pipe, an actuator used for driving the movable valve element to act so as to control the bottom injection channel to be opened when going down into the outer pipe is arranged on the inner pipe, and the inner pipe is provided with an inner injection channel making an inner cavity of the inner pipe communicated with the bottom injection channel when the bottom injection channel is opened. The separate injection string controls on-off of the bottom injection channel on the outer pipe through the actuator arranged on the lower portion of the inner pipe, thephenomenon that well killing operation is conducted by means of well killing fluid is avoided, and the construction cost is greatly lowered.

Description

technical field [0001] The invention relates to the field of oil and gas field exploitation, in particular to a split injection pipe string. Background technique [0002] As the oilfield enters the later stage of development, the water injection pressure continues to increase. In order to ensure safe production, it is necessary to release the pressure or kill the well before operating the pipe string. The use of pressure relief means increases the construction period, wastes injection energy, and easily damages the casing due to the large change in pressure difference. On the one hand, the use of high-density well killing fluid increases the operation and construction costs. On the other hand, well killing is easy to cause pollution to the formation, and the formation is crushed to death, resulting in a sharp drop in the permeability of the reservoir near the wellbore, and the oil, gas and water in the formation cannot flow into the wellbore. . [0003] The utility model p...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a separate injection pipe string to solve the technical problems in the prior art that the pipe string cannot be tripped without snubbing and the construction cost is high

Images