Gas lift reverse circulation sand washover well washing process and equipment for sandstone geothermal well

Abstract

The invention provides a gas lift reverse circulation sand washover well washing process and equipment for a sandstone geothermal well. The process comprises the following steps: in a sand washover process, compressing gas in a gas storage tank by an air compressor to form compressed gas; feeding the compressed gas into a gas injection tube from a high-pressure pipeline through a gas feeding tubevia a cavity between an internal body and an external body; then delivering the compressed gas from a gas injection tubular column and a gas mixing tubular column to a gas mixer and mixing the compressed gas with sand washover liquid to generate a gas lift effect; and raising gas, liquid and solid three-phase liquid flow lifted by gas from a sand washover oil tube and then enabling the gas, liquidand solid three-phase liquid flow to enter the internal body of a double-walled gas injector and a water eye of a lower joint so as to reach a ground liquid storage tank via the high-pressure pipeline. The equipment comprises the double-walled gas injector, the gas injection tubular column, the gas mixing tubular column, a sand washover nib and a sand washover drill bit. By a gas lift reverse circulation sand washover technology, a circular suction ability is high, raising of well bottom or water layer settled sand is facilitated, moreover, the sand washover liquid flow can carry large dirtysand particles, repeated breakage of the dirty sand particles is reduced, and therefore, the sand washover efficiency is improved.

Description

technical field [0001] The invention belongs to geothermal well sand flushing technology, in particular to a sandstone geothermal well gas lift reverse circulation sand flushing technology and equipment. Background technique [0002] Gas-lift reverse circulation sand flushing technology is one of the key technologies for sandstone geothermal wells. After sandstone geothermal wells are completed, it is necessary to circulate and clean the wellbore and wellbore in the production interval (water intake layer). , with the development time of the sandstone geothermal well, the energy of the formation decreases, and the sand production becomes more and more serious, and the sand particles enter the bottom of the well with the liquid flow. Some of the sand deposition wells form sand burial or sand plugging. In severe sand plugging, the height of the sand column in the well can reach more than hundreds of meters, submerging the aquifer. Increased water flow resistance can reduce th...

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Problems solved by technology

[0006] (2) Ground and downhole equipment wear

After the sand is produced from the formation, some smaller particles enter the surface equipment process together with the produced fluid, causing wear and tear on surface pipelines, heat exchange stations and other equipment; some particles are deposited at the bottom of the well, causing wear and tear on submersible pump equipment, resulting in submersible Reduced pump efficiency, shutdown of geothermal wells, necessary repairs and replacement of equipment, rising costs

[0008] (3) The casing is damaged and the geothermal well is scrapped

[0009] There are two main reasons for casing damage due to sand production in the water layer: first, long-term sand production produces friction on the mesh-wrapped water filter pipe, which increases the diameter of the mesh-wrapped wire filter pipe, and the wall thickness of the casing becomes thinner. The strength is reduced, leading to casing damage; the second is the most serious situation, with the continuous increase of formation sand production, the formation cavity outside the production casing is getting larger and larger, and to a certain extent, it often leads to sudden formation collapse , so that the protective effect of the contact surface between the formation and the casing is weakened, causing damage to the casing, and in severe cases, it may lead to scrapping of the geothermal well

[0010] (4) Workover workload increases

[0033] In most cases, due to the leakage of the formation, part of the sand is squeezed into the formation during sand washing, and during production, the sand squeezed into the formation flows back into the well and accumulates to form a sand plug, thus greatly shortening the sand washing cycle; and repeating The frequency of sand washing increases with the degree of leakage, which results in higher sand washing costs and reduced production of geothermal wells

[0034] ③Long recovery period

[0035] With the existing sand cleaning technology, it takes a long time for geothermal wells to resume production after construction operations. Submersible pump sand pumping and sand fishing operations make it take at least 5 days for geothermal wells to resume production, while geothermal wells caused by sand washing operations The time is at least 15 days or more. Therefore, it takes a long time for the resumption of production of geothermal wells after sand cleaning, and the production reduction is serious.

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