Al-Ansari, Adel (Saudi Aramco) | Parra, Carlos (Saudi Aramco) | Abahussain, Abdullah (Saudi Aramco) | Abuhamed, Amr M. (Saudi Aramco) | Pino, Rafael (Saudi Aramco) | El Bialy, Moustafa (Halliburton) | Mohamed, HadjSadok (Halliburton) | Lopez, Carlos (Halliburton)
A properly designed reservoir drilling fluid and precise control of its properties are essential to prevent formation damage issues that hamper production. An essential prerequisite for a reservoir drilling fluid are nondamaging specialty products and reduced fines and fluids invasion. This paper describes the case history of two deep gas wells in Saudi Arabia, one well showed impaired production due to screens plugging and was put on workover drilling operations whereas the other well was a regular development well. The offset data showed differential sticking, partial losses and tight spots while drilling the 8⅜ and 5⅞ in. hole sections.
The well reservoir data including the bottom hole-temperature – 300°F, permeability – roughly 10 to 20 micron pore throats and lithology – sandstone intercalated with shale, for the reservoir section were determined from offset analysis. Extensive lab testing was performed with nondamaging specialty and optimized PSD for minimized fine and fluids invasion. This engineered fluid was used to drill a 5⅞ in. vertical side track of ± 300 ft for the workover well whereas on the regular development well about ± 400 ft of the 5⅞ in. section was drilled. The fluid was continuously monitored for PSD at the rig along with the particle plugging test for fluid loss control. The hole cleaning and equivalent circulating density was monitored and programmed with a proprietary hydraulics software. All the fluid properties were determined to be within planned range. The wells were drilled without any of the offset problems as discussed above followed by running the 41/2 in. conventional sand screens to the bottom without any issue. Initial flowback production testing was performed on the workover well, which took 8 hours as compared to the usual 48 hours in the offset wells. The BS&W (basic sediment and water) from day 1 of production was 9% as compared to the 25% observed in the offset wells. The gas production rate was 200% more than was expected as per the offset information.
This paper shows the successful use of reservoir drill-in fluid on two gas wells: one was a workover well and another a regular well. The abstract presents a mutual approach between Halliburton and Saudi Aramco to address the issue of minimizing formation damage and mitigating differential sticking. Offset well data learnings, optimized PSD design, monitoring at the rig site, and the use of nondamaging specialty products delivered production optimization.
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.