Improvement of casing centering calculation model

Author of the article:YU Hao1, WU Lang2, JI Mengjia1

Author's Workplace：1. School of Petroleum Engineering, Yangtze University, Wuhan, Hubei, 430100, China; 2. Downhole Company, CNPC Chuanqing Drilling Engineering Co., Ltd., Chengdu, Sichuan, 610500, China

Key Words：Casing centering degree; Casing floating weight; Casing deflection; Casing eccentricity

Abstract：Cementing quality is an important factor affecting the integrity of oil and gas wells and casing centering degree is closely related to cementing quality. At present, the calculation model of casing centering degree does not consider the influence of liquid density difference inside and outside the casing, which is inconsistent with the field conditions, and the formula for calculating casing stress and deformation is not accurate enough, which affects the calculation accuracy of casing centering degree. Based on SY/T 5334—1996 model, the casing floating weight formula, casing deflection formula and casing eccentricity calculation method are modified, and an improved casing centering calculation model is formed. The comparison of improved model calculation resalts with the centering degree imaging logging data of Well Xiangchu 3 shows that the accuracy of the improved model is 3.214%higher than the original one, with the average error of 11.094%, which meets engineering requirements. So, the improved model is more accurate than the original one, and is of guiding significance for casing centering calculation.