Simulation device and simulation method for wellhead subsidence in frozen soil layer drilling process

Abstract

The invention provides a simulation device and simulation method for wellhead subsidence in a frozen soil layer drilling process. The simulation device comprises a low-temperature constant-temperatureexperiment box, a double-layer pipe, a drilling fluid circulation assembly, a drilling driving assembly and a displacement sensor, wherein sandy soil / clay with a preset moisture content is laid inside the low-temperature constant-temperature experiment box, and is used for forming a frozen soil simulation layer; the double-layer pipe comprises an outer pipe and an inner pipe positioned in the outer pipe; the outer pipe is inserted into the low-temperature constant-temperature experiment box; the drilling fluid circulation assembly is connected with the double-layer pipe, and is used for enabling drilling fluid with the preset temperature to circulate in the double-layer pipe; the drilling driving assembly is connected with the inner pipe, and is used for driving the inner pipe to move upand down and / or rotate; and the displacement sensor is used for monitoring the displacement of the outer pipe. The wellhead subsidence process caused by frozen soil layer melting in the polar region frozen soil zone drilling process can be simulated, and the influence caused by different wellhead loads, drilling fluid temperatures and frozen soil property parameters on the wellhead subsidence displacement is measured.

Description

technical field [0001] The invention belongs to the petroleum drilling industry, and in particular relates to a simulation device and a simulation method for wellhead subsidence during drilling in permafrost layers. Background technique [0002] Large areas of permafrost are widely distributed in the shallow strata of the arctic and sub-arctic low-temperature regions. The permafrost covers land and sea, with a thickness ranging from tens of meters to hundreds of meters. However, drilling in permafrost is very difficult. One of the important problems is that during the drilling process, due to the heat exchange between the drilling fluid and other circulating media and the formation and the cutting friction between the drill bit and the formation, the pore ice in the permafrost melts and freezes. The bearing capacity of the soil is greatly reduced. The Geological Survey of the Chinese Academy of Sciences drilled several test wells (DK1-DK4, MK1-MK2) in the Muli of the Qilian...

AI Technical Summary

Problems solved by technology

However, drilling in permafrost is very difficult. One of the important problems is that during the drilling process, due to the heat exchange between the drilling fluid and other circulating media and the formation and the cutting friction between the drill bit and the formation, the pore ice in the permafrost melts and freezes. The load-carrying capacity of the soil is greatly reduced

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