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Drilling oil-producing lateral wells often requires the use of an efficient drill-in fluid (DIF). A properly designed reservoir DIF with precise control of its properties is essential to help prevent formation damage that can impede production. This paper discusses the custom use of a DIF to reduce damage while drilling a lateral well to help maximize productivity during later stages.
Oil-based mud (OBM) with density of approximately 67 lbf/ft3 was formulated based on reservoir data by optimizing the particle size distribution (PSD) of the bridging materials used to effectively bridge against the average pore throat sizes. It was tested in the laboratory at simulated reservoir conditions and applied in the field at the target well. The fluid was continuously monitored at the rig for PSD and fluid loss control using the particle plugging test (PPT). The hole cleaning and equivalent circulating density (ECD) were simulated with proprietary hydraulics software.
Using nondamaging specialty products that reduce fines and fluids invasion is an essential prerequisite for a reservoir DIF. This paper describes the case history of drilling a horizontal well in a sandstone formation in Saudi Arabia and also shows the successful use of a reservoir DIF on lateral wells. It presents an approach that helps minimize formation damage, mitigate differential sticking, and drill a hole without having any hole problems. Implementation of this optimized fluid in the field while using specially designed practices to maintain the quality of the DIF during drilling led to a higher level of production rates.
This paper concludes that close monitoring of mud properties, optimization of PSD design, and the use of nondamaging specialty products helps minimize fluid invasion and deliver maximized production.