An Efficient Downhole Oil/Water-Separation System with Sucker-Rod Pump

Abstract

Summary At present, many oil fields in China have entered the high-water-cut production period, and the water cut of oil wells has continued to rise. Therefore, how to reduce the water cut of the produced liquid, reduce the amount of surface water treatment, shorten the ineffective water circulation, and reduce the comprehensive production cost have become the key problems restricting the sustainable economic exploitation of a high-water-cut oil field. To this end, the development model of circular displacement and the oil-recovery technology of a downhole oil/water-separation system with sucker-rod pump (DOWS-SRP) are proposed. The technology system consists of downhole oil/water-separation devices, an injection/production pump-string system, a sealing system, and downhole data-test system, mainly applied to separating the oil and water in the well through the separation device. The separated water is then directly injected into the formation and the separated concentrated liquid is lifted to the ground so the water injection and oil recovery are completed simultaneously in the same wellbore. The field-test data show that after the implementation of injection/production technology in the same well, the surface liquid-production volume decreased by 90%, the water-cut decreased by 27%, and the water/oil ratio decreased by 93%. In addition, the liquid volume of lifting, gathering, and treatment was greatly reduced, as well as the surface infrastructure investment, to achieve the purposes of cost saving, energy saving, and consumption reduction. At the same time, the downhole reinjection replaces surface water injection, transforming ineffective surface water circulation into effective internal displacement power in the reservoir and improving the yield and recovery rate. The successful application of the quaternary-oil-recovery block has made it possible to redevelop a large number of abandoned oil reservoirs, providing a potential basis for quaternary oil production. In addition, the preliminary energy-saving effect and economic-benefit analysis are performed. The data show that the energy-saving effect of this technology is obvious and good economic benefit is obtained.

A comprehensive review of sucker rod pumps’ components, diagnostics, mathematical models, and common failures and mitigations

“…The gravity separator relies on gravity separation based on density difference. This method is slower than the cyclone and has less efficiency (Jiang et al 2020). Figure 17 presents an illustration of both types of separators.…”

Oil–Water Separation using Synthetic Trees

“…Oil spills of up to hundreds of millions of gallons are catastrophic to ocean environments, − mandating regulations and research that could curb antifouling effects, protect marine life forms, and reduce damage to the ecosystem. − The efficient separation of oil from water is crucial for cleaning oil spills, as well as other applications like removing water from oil lubricants or wastewater purification. − Existing oil–water separation techniques employ membranes for the exclusion of either water or oil, with gravity ,,− or a pump − supplying the driving force. Additional mechanisms for oil–water separation include the use of sorbents, − , chemical disintegrators, , applied electric fields, , and membranes that are photoresponsive or thermally responsive. , …”

The Rod String Loads Variation during Short-Term Annular Gas Extraction

“…Numerous studies [6][7][8][9][10][11][12][13][14][15] have addressed the problem of finding technical solutions to reduce gas pressure in the annular space at various methods of well operation. A review Energies 2022, 15, 5045 2 of 13 in [16] illustrates tools to reduce the impact of gas on the operation of downhole sucker-rod pumps and their effectiveness under various operating conditions.…”

“…A large volume of gas at the pump's intake can reduce the overall pump efficiency by up to 60%, which is due to the late opening of the delivery valve during downward movement due to gas compression under the plunger [16]. Raising the level above the pump is one of the ways to control gas production using sucker rod pumps and since the gas has a lower density, it will flow up into the annulus of the well [15].…”