Laboratory Evaluation of Sealing Wide Fractures using Conventional Lost Circulation Materials

• Published in: All Days
• Main Authors: Al-Saba, Mortadha, Nygaard, Runar, Saasen, Arild, Nes, Olav Magnar
• Format: Text
• Language: unknown
• Published: Scholars' Mine 2014
• Subjects: Efficiency; Laboratories; Oil Well Drilling; Particle Size Analysis; Pelletizing; Petroleum Engineering; Breakdown Pressure; Constant Pressures; Design Treatments; Different Particle Sizes; Experimental Evaluation; Laboratory Evaluation; Laboratory Procedures; Lost Circulation Materials; Fracture; Geology; Barents Sea; Psi
• Online Access: https://scholarsmine.mst.edu/geosci_geo_peteng_facwork/1145; https://doi.org/10.2118/170576-MS

Preventing or mitigating fluid losses caused by the presence of natural fractures is a major challenge faced by operators when drilling exploratory wells in the Barents Sea. Natural fractures widths vary significantly which makes it difficult to design treatments using conventional lost circulation materials (LCM's). Different solutions have been used to overcome this problem, such as chemical sealants, hydratable LCM's pills, rigid-plugs and cement. This study intends to expand the usage of conventional LCM's in sealing wide fractures. Experimental evaluation of LCM's is a crucial step prior to field application. Currently, particle plugging apparatus is often used to evaluate LCM's performance using straight slots or tapered slots by applying a constant pressure and measuring the fluid loss. However, fluid loss values are not a good measure of the formed seal integrity. Therefore, another means of evaluating LCM's performances is required. In this work LCM sealing efficiency was defined as the seal/bridge maximum breakdown pressure. The tests were conducted on a fit-for-purpose apparatus designed to evaluate the performance of LCM's by measuring the sealing efficiency under high pressures (10,000 psi) and temperatures. This paper presents an extensive laboratory evaluation to investigate the feasibility of sealing wide fractures using conventional LCM's. The ability of different LCM's in sealing fractures was evaluated using a set of tapered slot sizes up to 2000 microns fracture width. Four different types of conventional LCM with 13 different particle sizes (D50) and one new foam wedge based LCM were investigated. A total of 200 tests were run to investigate the effect of different parameters on the overall performance of both conventional and unconventional LCM. These parameters include LCM's type, concentration, tapered slot size, particle size distribution (PSD), temperature, and injection rate. Ground walnut shell showed a superior performance in sealing large fractures (sealing pressure up to 2200 psi) ...