The present invention relates generally to submersible pumping systems that are used to raise production fluids from a well, and particularly to a system and method for removing solid particulates, such as sand, from the wellbore fluid upstream from the pump. The particulates may then be reinjected into the wellbore fluid stream discharged from the pump.
In producing petroleum and other useful fluids from production wells, a variety of submersible pumping systems are used to raise the fluids collected in a well. Generally, a wellbore is drilled into the earth at a production formation and lined with a wellbore casing. The casing generally includes perforations through which the production fluids may flow from the production formation into the wellbore. The fluids that collect in the wellbore are raised by the submersible pumping system to another zone or to a collection point above the surface of the earth.
One exemplary submersible pumping system is an electric submersible pumping system that utilizes a submersible electric motor and a submersible pump. The system further may include other components, such as sensor equipment, gas separators, and motor protectors for isolating the motor oil from the well fluids.
Also, a connector is used to connect the pumping system to a deployment system. A variety of deployment systems may be used to deploy the pumping system within a wellbore. For example, cable, coil tubing or production tubing may be utilized.
Power is supplied to the submersible electric motor via a power cable that runs along the deployment system. Typically, the power cable is banded or supported along either the outside or the inside of the deployment system. Generally, the power cable is routed to the electric motor to supply electric power thereto, and the motor powers the submersible pump by an appropriate drive shaft.
In many wellbore environments, the production fluids contains particulates, such as sand. These solid particulates are drawn into the submersible pump through a pump intake along with the production fluid. However, the solids can cause detrimental wear to the internal components of the submersible pump. For example, if a centrifugal type pump is used, the solid particulates can create substantial wear on the impellers, the diffusers and other internal pump components.
Submersible pumping systems also are used to inject water from one zone within a well to a second zone within the well, or to dispose of surface water to an existing aquifer. If the geologic formation surrounding the first zone is sandstone, then it is very likely that sand will be injected into the second zone. Forcing sand into an aquifer eventually cause the aquifer to plug and no longer accept fluid.
It would be advantageous to have a system and method for removing at least a portion of the solid particulates from the wellbore fluid upstream from the pump. It would also be advantageous to have a system that could reinject the solid particulates into the fluid stream discharged from the pump, if desired, or produce a fluid stream free of at least a portion of solid particulates.
The present invention features a system for pumping a wellbore fluid while reducing the detrimental effects of solids dispersed in the wellbore fluid. The system includes a submersible pumping system having a plurality of sequentially connected components arranged for deployment in a wellbore. Specifically, the submersible pumping system includes a submersible motor, a submersible pump and a solids separator. The solids separator is disposed to remove solid particulates prior to entrance of the solids into the submersible pump.
According to another aspect of the invention, a submersible pumping system is provided to reduce wear on a submersible pump by routing solid particulates around the pump. The system includes a submersible pump able to intake a fluid and discharge the fluid in a fluid discharge stream. Additionally, a particulate separator is disposed to receive wellbore fluid prior to entrance of the fluid into the submersible pump. The particulate separator has a separator region and a particulate collection region where the solid particulates may be concentrated.
The system further includes a pressure reduction device having a venturi disposed to receive the fluid stream discharged from the submersible pump. This creates a low pressure region proximate the venturi that permits reinjection of the solid particulates into the wellbore fluid discharged by the pump. A bypass is connected between the particulate collection region of the particulate separator and the low pressure region proximate the venturi. The low pressure draws a concentrated mixture of solid particulates and fluid from the particulate collection region through the bypass and into the fluid stream being discharged from the submersible pump. In other words, solid particulates are routed around the submersible pump to reduce wear on internal pump components.
According to another aspect of the present invention, a method is provided for pumping a production fluid. The method includes powering a submersible pump with a submersible motor, and intaking a wellbore fluid intermediate the submersible pump and a fluid intake. The method further includes separating solid particulates from the wellbore fluid to be pumped by the submersible pump. Following separation, the solid particulates may be reinjected into a fluid discharge stream of the submersible pump.