基于改进蚁群算法的海上稠油热采井钻井顺序优化

Drilling sequence optimization of offshore heavy oil thermal wells based on improved ant colony optimization algorithm

蒸汽吞吐是广泛应用的稠油开采方式之一。海上稠油区块钻井作业成本高,故钻井的同时对邻近已完钻井进行注热,该模式可大幅提高钻采效率,然而存在注热井蒸汽窜至在钻井风险。本文对热采井的汽窜风险进行了研究,并提出了改进蚁群算法,以求解出满足安全距离且钻井总工期最短的钻井顺序。首先,构建了三维储层,模拟向井底注热时井周温度场与压力场分布规律。结果表明,向非均质储层注热时,蒸汽易沿高渗通道突进,9 d时间窜流距离可超90 m。其次,对蚁群算法做出了改进,将归一化的井底最小距离引入位置转移概率,将钻井停工时间引入信息素更新策略,优化求解钻井顺序。结果表明,针对渤海油田典型案例,当设定安全距离为400~460 m时,该算法较人工选取法可节约钻井总工期15~30 d。本文提出的改进蚁群算法可以快速高效求解出钻井总工期最短的钻井顺序,为钻进顺序的优选提供了定量化计算方法,对节约钻井成本、增强海上稠油热采井钻井安全性具有重要意义。

Steam stimulation is widely applied in heavy oil production.The cost of drilling in offshore heavy oil field is high,so that the mode of drilling other wells and injecting heat into the completed wells at the same time can greatly improve the efficiency of drilling and production.However,there is a risk of steam from heat injection well leaking into the drilling well.This paper studies the risk of steam channeling in thermal production wells,and proposes an improved ant colony optimization(IACO)algorithm to solve the drilling sequence that meets the safety distance and has the shortest total drilling period.Firstly,a three-dimensional reser-voir was established to simulate the distribution of temperature and pressure fields around the well when injecting heat into the well.The results show that when injecting heat into heterogeneous reservoirs,steam is prone to break through along the high-permeability channels,and the channeling flow can exceed 90 m in 9 days.The results show that,for typical case of Bohai Oilfield,the algorithm can save 15~30 days of total drilling time compared with the manual selection method when the safety distance is set to 400~460 m.The IACO algorithm proposed in this paper can quickly and efficiently output the drilling sequence with the shortest drilling duration,which provides a quantitative method for the optimization of the drilling sequence.It is of great significance for saving drilling costs and enhancing the drilling safety of offshore heavy oil thermal recovery wells.