Wellbore Strengthening: Palm Date Seeds for Mitigating Circulation Losses and Effect of Salinity on Clay Swelling

Abstract

Abstract Drilling through depleted and Deepwater formations are often challenging because of various wellbore instabilities such as weak zones, abnormally pressured, and/or highly swelling zones that could trigger severe circulation losses, blowouts, wellbore sloughing, enlargement, and stuck drill pipe. Considering the consequential expenses of non-productive time, it is essential to determine the root cause of wellbore instabilities, to initiate the appropriate mitigation measures. Therefore, this work was structured to review lost circulation and shale swelling challenges, mechanisms, and control strategies. Firstly, this research work has investigated palm date seeds (DS) as loss circulation and a bridging material. Processed palm seeds were sieved into various particle sizes and added in different mass and size ratios to the formulated oil-based mud. Sand-bed and HPHT filtration experiments were conducted to investigate the DS filtrate control potential. The filtrate loss and the mud cake thickness of the DS mud samples ranged between 4.2 ml to 4.8 ml and 1mm to 3mm, respectively. The conducted LCM comparative evaluations have shown that DS had the least filtrate control potential and the least competent mud cake. However, in the sand-bed experiment, DS LCM was able to withhold the mud in the sand column despite the high filtration depth. Secondly, this research work also investigated the effect of salinity on clay hydration. Therefore, using a viscometer to measure the yield point of a sample bentonite slurry, it was observed that (KCl + bentonite) had a 95% yield point reduction compared with (freshwater + bentonite).