Experimental study on the controlling factors of frictional coefficient for lost circulation control and formation damage prevention in deep fractured tight reservoir

Working fluids loss is a major contributor to low productivity during production process of fractured tight reservoirs. Lost circulation control effect directly related to the tribological behavior between fracture surface and lost circulation materials(LCMs). In this study, the friction coefficient(FC) was investigated using typical clastic rocks and LCMs by considering multiple effect factors divided into external condition and internal condition. The results show that normal load had a relatively high effect on sliding model. A positive correlation was observed between FC and asperities heights. FC decreased induced by particle size degradation of rigid LCMs. Elastic LCMs manifested higher FC compared with rigid LCMs. Under the lubrication condition by working fluid, FC of rigid LCMs was mainly controlled by their surface wettability. FC of organic LCMs is more sensitive to high temperature aging than inorganic LCMs. Fracture plugging experiments show that LCMs optimized based on the research results can effectively improve the efficiency and strength of fracture plugging.