A device and method for sand removal in marine natural gas hydrate production wells

Abstract

The invention provides a device and method for desanding of a submarine natural gas hydrate exploitation well. The device comprises a gravel filling set, a centrifugal desander, a submerged pump and a connecting flange. The gravel filling set is arranged at the bottom of the exploitation well, the centrifugal desander and the submerged pump are connected through the connecting flange and wholly descend to the bottom of the exploitation well, and the outer wall of a flow guide chamber is attached to the inner wall of the gravel filling set. By the adoption of the device, in the centrifugal desanding process, gas-water sand is firstly decomposed and flows to a shaft, large settled layer sand is blocked by the gravel filling set, and gas and water containing fine sand enters the shaft; gas and water containing the fine sand enter an upper collection box through the flow guide chamber and an inflow port, and cyclones are generated; under the effect of centrifugal force, the fine sand is gathered on the inner wall of a settling chamber and descends into a sand collection box. By the adoption of a secondary desanding method, desanding efficiency is improved, and permeability of a hydrate settled layer cannot be remarkably affected; by the adoption of a cyclone centrifugal mode, the fine sand and decomposed gas and water can be effectively separated, the fine sand is prevented from entering the submerged pump, and equipment wear is reduced.

Description

technical field [0001] The invention relates to a device and method for sand removal in marine natural gas hydrate production wells, and belongs to the technical field of exploitation of marine oil and gas reservoirs (including new oil and gas reservoir resources such as natural gas hydrates). Background technique [0002] Sand production in oil and gas wells is due to the destruction of the rock formation structure near the bottom of the production well, which causes sand particles to move to the wellbore with the fluid. In severe cases, it will cause a decrease in permeability, blockage of tubing, and a decline in production. The natural gas hydrate production process is accompanied by the decomposition of the hydrate layer, and the original cementation state changes. A large number of sediment particles that can flow with the decomposed gas and water are produced near the production well, and the problem of sand production is more serious than that of conventional oil and ...

AI Technical Summary

Problems solved by technology

However, in order not to affect the production efficiency, the filter pore size of the sand filter tube should not be too small, so it is still impossible to prevent the sand with a smaller particle size from entering the wellbore, and the impact of the fine particle size silt on the wear of the wellbore and the pump cannot be ignored, so It is necessary to further isolate the movement of fine silt to the wellbore

Most of the traditional mechanical desanding devices adopt the filtering method (such as ZL99254473.4), however, the filtering effect is limited by the mesh size of the filter mesh, if it is too large, it will not be able to filter fine sand; if it is too small, it will easily cause blockage

Unable to meet sand removal requirements

In addition, there are methods of sand removal using cyclone (ZL00215037.9, ZL200820122916.4, CN203214037), but due to structural limitations, most of these devices can only be arranged at the exit of wells on the ground, and do not fundamentally solve the problem of sand removal before wells. question

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