| Title | Improvement of CMC on the Performance of CGA Drilling Fluids for Geothermal Drilling |
|---|---|
| Authors | Wenxi ZHU, Xiuhua ZHENG, Li ZENG |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | geothermal well drilling, carboxymethyl cellulose, CGA drilling fluid, rheology, filtration loss |
| Abstract | Colloidal Gas Aphron (CGA) drilling fluids have been successfully used in petroleum industry to drill low depleted reservoirs. Recently, it has also been introduced to drill geothermal reservoirs of low-pressure and fractures. The rheological and filtration properties of drilling fluids are closely related to the cuttings carrying ability and the reservoirs invasion. Therefore, improving drilling fluid performance, especially at high temperature, will effectively increase the drilling efficiency and reduce the costs. In this paper, 0.2%-0.6% carboxymethyl cellulose (CMC) was added as viscosifier and fluid loss control agent to improve the performance of CGA drilling fluids at room temperature and 130℃ aged. Results show that:1) Power law model is the optimal model to describe the rheological behaviors of CGA drilling fluid containing CMC; 2) The addition of CMC significantly increased the LSRV and apparent viscosity of the CGA drilling fluid. CGA drilling fluid with or without CMC has significant shear thinning behaviors and the dosage of CMC has an influence on the strength of shear thinning behaviors; 3) The addition of CMC effectively reduces the fluid loss, whether at room temperature or 130℃. Compared with the control group without CMC, the filtration loss of CGA fluid containing 0.6% CMC was reduced by 62.5% and 46.7% at room temperature and 130℃, respectively. |