Loss circulation in drilling and well construction: The significance of applications of crosslinked polymers in wellbore strengthening: A review

Loss circulation is one of the major concerns in drilling and well construction. The uncontrolled flow of fluids into formation while drilling or primary cementing lead to substantial non-productive time (NPT). The methods of wellbore strengthening (WS) maximize the pressure that the wellbore can withstand before fractures is initiated or propagated, which is the key parameter in prevention and mitigation of loss circulation. The cross-linkable polymers among various loss circulation materials (LCM) are considered an efficient plugging material that can seal wide range of fracture sizes, strengthen the wellbore and provide solution for lost circulations under extreme drilling conditions. This paper reviews the applications of wellbore strengthening and summarizes various filed practices used for preventive and corrective treatment of loss circulations. The paper highlights the development of crosslinked polymers for wellbore strengthening and the significance of using acrylamide polymer systems as LCM. The review also covers the application of commercially available types of polymers and crosslinkers and their performance in high pressure/high temperature (HPHT) wells. The loss circulation in geothermal drilling, and in challenging HPHT is discussed. The types of formations cause loss circulation, the methods of locating loss zones, and summary of recent literatures on the effect of crosslinking process on gelation time, thermal stability and formation damage is also included.