Method and device for mechanically removing sand and draining liquid from pit shaft of oil/gas well in underbalanced state

Abstract

The invention discloses a method and device for mechanically removing sand and draining liquid from a pit shaft of an oil / gas well in an underbalanced state. In the underbalanced state, kinetic energy of working solution is converted into mechanical energy of a spiral drill bit, and a sand body is cut and lifted and then returns to the ground along with the working solution; and after sand is removed, liquid drainage process gas is injected into the pit shaft to drain accumulation liquid in the pit shaft, so that production of the oil / gas well can be restored. According to the method and device for removing sand and draining liquid, the velocity pressure of a working solution column is lower than the formation pressure during the sand removal process, so that the working solution is prevented from leaking effectively, and pollution to the formation can be reduced; kinetic energy of the working solution is converted into mechanical energy of the spiral drill bit, and the sand body depositing in the pit shaft is cut and lifted, so that formation damage caused by hydrodynamic impact can be prevented effectively, and complex circumstance of the formation can be prevented from being induced; and a gas injection auxiliary liquid drainage device is adopted to discharge working solution in the well, so that formation energy can be activated step by step advantageously, steady flow state of gas, liquid and oil can be established, and production of the oil / gas well can be restored quickly.

Description

technical field [0001] The invention belongs to the technical field of oil field development equipment, and relates to a method and device for mechanically removing sand and draining liquid in an oil and gas well shaft under an under-balanced state. Background technique [0002] In the process of oil field development, the sand and dust particles carried by oil and natural gas will gather and deposit in the wellbore; especially for siltstone and argillaceous siltstone, they have the characteristics of undercompaction, poor diagenesis, loose cementation, high clay and high mud. For strata with high salinity, high salinity, and high sensitivity, sand production is more serious during oil and gas production; oil and gas wells using forced drainage and strong recovery techniques and oil and gas wells exploited for long-term water injection or gas injection, due to damage to the stratum structure or reservoir If the skeleton is destroyed, the sand will be aggravated. According t...

AI Technical Summary

Problems solved by technology

The disadvantage of this technology is that sand washing with high pressure and large displacement will damage and pollute the formation. It is more harmful to oil and gas wells with low formation pressure or leakage. For oil and gas wells with fragile geological structures, it will also cause serious downhole complications. situation, and even lead to the collapse of production layers, etc.

[0005] The sand dredging pump developed in recent years is affected by many factors such as well deviation, subsidence, sand surface hardness, and sand density, so its application is limited.

[0006] Field practice shows that quite a lot of wellbore sand deposits of oil and gas wells accumulate into tight sand columns under pressure for a period of time; Become strong and tough sand nodules and sand columns; the above problems make sand washing and sand pumping work more difficult

At the same time, there is no effective drainage process after the current sand washing operation

The geological structure of sand-producing oil and gas fields is inherently very fragile. Using high-pressure gas lift or liquid nitrogen to assist drainage will cause impact and disturbance to the formation, induce complex conditions in the formation, and is not conducive to the establishment of a stable flow state of gas, water, and oil in the formation. lead to production failure

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