A novel material evaluation method for lost circulation control and formation damage prevention in deep fractured tight reservoir

Abstract

Lost circulation induced by working fluid loss into formation fractures often leads to safety, environmental and economic issues, which has hindered the exploitation of oil, gas and geothermal resources for years. Fracture plugging with loss control materials is the most commonly used method for lost circulation control. However, traditional material selection is mainly guided by trial-and-error method. This paper proposes a novel material evaluation method for the systematic and scientific selection of loss control material. The new method consists of four steps: key material parameters determination, parameter weight calculation, parameter experimental evaluation, and material quantitative scoring. Fracture plugging strength model is analyzed to determine the key material parameters accounting for fracture plugging strength and the requirement of plugging removal before production. Analytic hierarchy process is adopted to calculate the material parameter weight. Experiments are designed to evaluate the material parameter levels. Quantitative scoring model is proposed to finally determine the material integrated score for the quantitative evaluation and scientific selection of loss control material. The reliability of the proposed evaluation method is validated by fracture plugging experiments. High-score materials are selected to form loss control formula based on the proposed evaluation method and successfully applied to gas field in Tarim Basin, China.