Additively Manufactured Fracture Disk for Testing Shape Memory Polymer Based Lost Circulation Material for Geothermal Applications

Abstract

Lost circulation is the most extensive and expensive operational problem documented in geothermal well-construction. Mud losses have a high impact during drilling geothermal wells, mainly due to their high frequency and the associated high cost. The highly fractured rock environment found in geothermal drilling is one of the most common causes of massive mud loss events. Fractures that measure thousands of microns are complicated to cure. Operational consequences of loss circulation are diverse, but the most critical one is stuck pipe and well-control issues. These events represent a significant impact on NPT in geothermal wells. Despite being widely studied, lost circulation is still the most problematic and expensive issue in geothermal drilling. The most utilized corrective approach to prevent lost circulation is using lost circulation materials (LCM). The intention is to bridge and seal the wellbore fractures. Researchers have studied the bridging and sealing efficiency of different LCMs using slotted disks to recreate geothermal fractures. However, natural fractures are irregular, with randomness in their size and shape. In this case, materials successfully tested in the laboratory cannot replicate the same performance in field operations. This paper presents a novel approach for building a fracture using additive manufacturing to test shape memory polymer-based lost circulation material. Additive manufacturing allows for the production of objects with accurate geometric shapes. In this case, a fracture was designed, which was inspired by a natural fracture shape from a wellbore image log, and printed by a 3D printer. The novel fracture disk was used to test the shape memory polymer-based lost circulation material. Shape memory polymers can be programmed to expand at downhole high temperatures. The results show that shape memory polymers can seal and bridge the complex fracture by adding sealing pressure and supporting a wellbore strengthening strategy.