Jia Ying, Zhang Juntao, Shen Nan, Xu Feng, Li Junjian, Zhang Pengyi, Zhang Chuanying
Development Dept, CNPC International (Chad) Co., Ltd, BP2519 N'Djamena, Chad.
College of Petroleum Engineering, China University of Petroleum, 102249 Beijing, China.
ACS Omega. 2024 Nov 14;9(47):47213-47221. doi: 10.1021/acsomega.4c08166. eCollection 2024 Nov 26.
The application of thermal recovery methods in Chad's heavy oil fields has proven to be challenging, necessitating the development of chemical cold production technologies. The mechanisms causing heavy oil viscosity remain unclear, and the effects of adding viscosity reducers in wells with varying water contents are not well understood. In this study, the composition and structure of Chad's heavy oil samples were experimentally analyzed, revealing that the viscosity is primarily due to the accumulation of isoprenoid-like components and the high concentration of side-chain naphthenes in the oil's saturated fraction. Based on this mechanism, viscosity reducers were screened, with DG, a high-molecular-weight water-soluble viscosity reducer, demonstrating the most effective results. Numerical simulation was then employed to characterize the mechanism of viscosity reducers and to model the impact of adjusting daily production rates and introducing viscosity reducers in wells with different water contents on the cumulative oil recovery. The field numerical model was used to simulate for 10 years, and the results showed that for high water content wells, the injection of viscosity reducer reduced the daily fluid volume by 10%, and the cumulative recovery rate increased by 6.75%; for low water content wells, the injection of viscosity reducer increased the daily fluid volume by 20%, and the cumulative recovery rate increased by 3.08%. This research aims to provide new insights into the development of heavy oil reservoirs.
热采方法在乍得稠油油田的应用已被证明具有挑战性，因此需要开发化学冷采技术。导致稠油粘度的机理尚不清楚，在不同含水量的油井中添加降粘剂的效果也未得到充分理解。在本研究中，对乍得稠油样品的组成和结构进行了实验分析，结果表明，粘度主要是由于类异戊二烯类组分的积累以及油的饱和馏分中侧链环烷烃的高浓度所致。基于这一机理，筛选了降粘剂，其中高分子量水溶性降粘剂DG表现出最有效的结果。然后采用数值模拟来表征降粘剂的作用机理，并模拟调整日产量以及在不同含水量油井中引入降粘剂对累积采油量的影响。利用油藏数值模型进行了10年的模拟，结果表明，对于高含水油井，注入降粘剂可使日产液量降低10%，累积采收率提高6.75%；对于低含水油井，注入降粘剂可使日产液量提高20%，累积采收率提高3.08%。本研究旨在为稠油油藏开发提供新的见解。
