New Low-Solids OBM Demonstrates Improved Returns as Perforating Kill Pill

摘要

This paper describes the development of a low-solids oilbasedfluid and its successful application as a kill pill in longhorizontal well perforations in the Norwegian North Sea. Theauthors detail the investigative process that resulted in thedevelopment of the cesium formate-based internal phasefluid system.Simulated perforation formation damage tests with andwithout zinc debris were conducted on conventional brinebasedand oil-based fluid systems. The tests showed thechemical reaction of the brine-based system to zinc debris hadlittle effect on return flow efficiency, but significantlyincreased fluid loss. With the conventional oil-based mud,returns dropped to 10-15% when the zinc debris was added.The newly developed low-solids oil-based kill-pill systemwas engineered with a high content of heavy brine for fluiddensity and minimal solids content. The only solids in thesystem are calcium carbonate, which is used for bridging, andminimal amounts of clay and lime for rheology control andalkalinity, respectively. In perforation tests it exhibited morethan 80% return flow efficiency.