Case Study at CNOOC SES Ltd: Screen-Less Sand Control with Polymer Based in Low Reservoir Pressure to Improve ESP Run Life in Well X and Y in the Wanda Field
Year: 2018
Proceedings Title : Proc. Indon. Petrol. Assoc., 42nd Ann. Conv., 2018
The Wanda Field is one of the fields operated by CNOOC SES Ltd which is located in the South-East Sumatra Block. The field has channelized sandstone reservoirs and is located near a major fault with many minor faults extended perpendicular to the major fault across the field. The fault compartmentalization has created limitations on reservoir pressure which leads to fast production decline and there are also sand problems. This field started producing oil in 1984 from well X with a production rate of 2882 BOPD and trace water cut and reservoir pressure of 1700 psi. Currently the reservoir pressure has been depleted to 989 psi and the well has experienced sand problems. Another well with different sand in the Wanda field (Well Y) also experienced sand problems due to lower current reservoir pressure of 226 psi. Sand production creates short period run life of ESP due to sand production. Pump stages are eroded by sand and shaft rotation becomes stuck since pump stages are full of sand. The shaft was broken due to higher torque while dealing with sand production and sand control is required to overcome this problem. The technology options for sand control to be chosen in this field are very limited due to low reservoir pressure. Mechanical sand control such as gravel pack, standalone screen and expandable sand screen are less preferable because of lowering productivity index. Screen-less sand control with polymer based is appropriate because it has lower risk in reducing productivity index. It is injected under the form of aqueous solution and forms a polymer film which coats the surface of the rock, thus preventing rock cement erosion around the wellbore instead of filling pore with gel/resin. It is also environmentally friendly. This technology has been applied successfully in two wells in the Wanda Field. In summary, this technology successfully improves the run life of ESP and delivers optimum production.
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