Drilling fluid wall protection technology for loose and fractured strata in the Shenjing exploration area in Zhongwei City， Ningxia

Abstract:

In the initial stage of drilling construction for the coal resource exploration project in the Shenjing Exploration Area of Zhongwei City, Ningxia Hui Autonomous Region, due to complex formation conditions including loose and fractured rocks and formation loss, it was difficult to stabilize the borehole walls. This resulted in substandard core recovery rates, low construction efficiency, and high costs, with the monthly rig efficiency only reaching 353 meters per month.By analyzing the geotechnical engineering geological characteristics and physical and mechanical properties of rocks in the exploration area, the drilling construction technology and drilling parameters were adjusted, and the drilling fluid formula was optimized. The low-solid-phase polymer film-forming wall-protecting drilling fluid system developed by the Beijing Institute of Prospecting Engineering was adopted, which improved the performance of drilling fluid in protecting borehole walls and cores. The filtration loss of drilling fluid decreased from 25ml/30min to 9ml/30min, a reduction of 64%. The average core recovery rate increased from 53% to 84.41%, an increase of 31.41%, and the average monthly rig efficiency rose from 353m/month to 757.87m/month, an increase of 115%.The subsequent construction of 9 boreholes proceeded smoothly, with a total drilling footage of 4774.6 meters completed, providing a reference for drilling construction in similar areas.