Integrated Geophysical Approaches for Assessing Lost Circulation While Drilling in the Shiranish Formation, Saddle Area of the Rumaila Oilfield, Southern Iraq

Abstract

Abstract Loss of circulation while oil well drilling is a major problem and is regarded as the most challenging difficulty during drilling and well construction. A significant circulation loss can result in drilling risks such as sticking, blowout and well collapse. This research focused on Shiranish Formation downhole mud losses while drilling and stuck pipe in the saddle area of the Rumaila super giant oilfield, in southern Iraq. Over 1100 wells were drilled in the Rumaila oilfield and only a few wells within the saddle area experienced downhole formation losses/problems and stuck pipes. Seismic data, petrophysical data and drilling reports were used to investigate Shiranish Formation loss and stuck pipe issues. The seismic interpretation revealed small-scale faults and fractures within the examined area, most likely influenced by the strike-slip deep-seated Al-Hammar fault. Correlation within three wells was performed to understand the effect of these faults within the Shiranish Formation, which demonstrated that the Shiranish Formation top is roughly 40 m different from the neighboring wells within 1.5 km and other formation tops are not affected within these faults. Identifying the location of faults and fractures will aid in avoiding drilling in these particular areas and choosing locations where there are no faults, or at the very least in mitigating and assisting the risk of drilling in such areas, such as controlling the rate of Penetration (ROP) while drilling and preparing extra mud and lost circulation materials (LCM).