Optimization and Performance Evaluation of Plugging Scheme for Fracture Leakage in Gas Storage Drilling

Abstract

Serious fracture leakage often occurs in the drilling process of gas stor¬age construction in Jidong oilfield. Because of the mismatch between plugging formula and the formation, the plugging effect is not good or even the leakage can¬not be blocked. Well loss not only causes great economic loss, but also seriously affects the construction progress of gas storage. In this paper, the optimization of plugging formula for gas storage in Jidong Oilfield and the evaluation of plugging effect of plugging formula are carried out to solve this problem, and the numerical simulation mathematical model for plugging fracture in Jidong oilfield is estab¬lished. The simulation of loss rate and loss amount under the condition of 0.3 mm, 0. 4 mm, 0.5 mm, 0.6 mm and 0.7 mm particle size of plugging agent was carried out. The simulation of loss rate and loss amount under the condition of different particle size was obtained, and the average particle size of plugging agent was obtained between 0.5 and 0.6 mm. At the same time, three particle size range of 0. 1-0.4mm, 0.4-0.8 mm and 0.8-1.2 mm were carried out to simulate the plugging effect of different composite particle size formulations (five formulations), and the loss rate and cumulative loss of different formulations were obtained. The optimal plugging effect formula was 4% (0.1-0.4 mm) + 2% (0.4-0.8 mm) + 1.8% (0.8¬1.2 mm). In addition, the high temperature and high pressure static and dynamic plugging apparatus of dust-3 is used to carry out high temperature and high pres¬sure dynamic plugging evaluation experiments of two kinds of compound particle size formulas. The cumulative leakage curves of different compound formulas are obtained, and the plugging mechanism of cracks in gas storage is revealed. The plugging effect of scheme 1 with plugging agent is superior to scheme 5 with plugging agent. Through comparative analysis, the simulation results and exper¬imental results are in good agreement, which further proves the accuracy of the simulation method and results.