Experimental investigation of deformable additives as loss circulation control agent during drilling and well construction

Lost circulation is known as one of the most important challenges during drilling. In addition to high costs due to mud loss and nonproductive time, lost circulation may lead to several consequences, including stuck pipes, wellbore collapse, poor hole cleaning, and well control issues. Different materials and techniques have been tested in the literature and recommended to prevent and control drilling fluid loss. One of the most common solutions is using conventional Lost Circulation Materials (LCMs) that are widely used in the industry. This paper aims to investigate the performance of two deformable LCMs, rubber and synthetic fiber, in order to control fluid loss in fractured formations. This deformability helps the LCM to be compressed and forced into openings of different sizes and shapes. The effect of LCM formulation, Particle Size Distribution (PSD), LCMs combination, fracture width (1000 and 2000 microns), temperature, and fine particles (i.e., smaller than 297 microns) on the ability of LCMs to mitigate lost circulation in water-based drilling fluids was studied. The sealing efficiency of LCMs was investigated through the dynamic sealing tests to optimize the particle size distribution and assess the maximum pressure that the LCMs can withstand in the fractured formations to prevent further fluid loss. The results indicated that the fracture sealing significantly depends on the formulation design of LCMs, so PSD optimization should be considered for better control of fluid loss. Adding fine particles and using a broad PSD increases the sealing pressure and fracture sealing rate. The comparison of the two LCMs showed that rubber has a higher sealing rate and less fluid loss compared to synthetic fiber. Furthermore, the synergistic use of LCMs is a better loss control solution compared to their individual employment.