The main objective was to improve downhole sand separation to prolong ESP run life, reduce the number and frequency of workovers, and decrease production deferment, improving cash flow.
Shell traditionally used desander tools with six joints of tailpipe and a bull plug in every ESP well as a standard sand mitigation effort. Desanders are installed below the ESP as part of the bottomhole assembly (BHA), and centrifugal action separates solid particles from well fluids and stores them in the tailpipe. When the tailpipe is full, the sand passes through the centrifugal pumps with the well fluid, eroding the ESP pump stages, bearings, and shafts and degrading lift capability. In addition, sand deposition within the pump leads to ESP motor overloading, which damages the electrical integrity of the ESP. When the electrical system fails, Shell must pull the BHA out of the well and replace it with new equipment.
In Shell's experience, the tailpipe fills with sand after about 3 to 6 months of production, causing the ESP to fail soon afterward.
The PumpGuard intake sand control screen and valve assembly comprises a 3D filter capable of filtering out particles of 15–600 um and a valve assembly that creates a secondary flow path. A MeshRite™ stainless steel wool screen catches large quantities of sand and solids, including particle sizes much smaller than those separated by the desander. When the screen is plugged, the PumpGuard assembly valve opens to enable unfiltered flow up the screens and into the ESP. The system can handle more sand compared with a desander tailpipe, thus extending ESP run life.
Shell ran these pump protection systems with SLB and third-party ESPs. The run life of the ESPs improved by an average of 35%, with constant production volumes and slow drawdowns. In addition, the number of ESP shutdowns related to sand and solids was reduced by more than 90%, improving longevity of electrical components. The success rate of ESP startups after planned and unplanned shutdowns also improved—by 32%.
The increased uptime improved Shell's business performance, even considering the cost of the sand control systems.
The field data enables Shell to select the optimal sand control system, based on value, for ESP wells in fields known for downtime caused by severe sand production.
Read technical paper SPE-207926.
