Feasibility Analysis on Optimization and Expansion of Ultra-Deep Well Casing Program in Fuman Oilfield

With the continuous deepening of exploration and development for Fuman oilfield, the existing casing program fails to effectively deal with downhole problems such as “overflow, leakage and collapse” caused by local high-pressure brine developed layer, leading to longer drilling time and higher drilling safety risk. Therefore, it is urgent to optimize the existing casing program according to the characteristics of geology and engineering to meet the requirements of safe drilling. For this purpose, the three types of pressure profiles in the Fuman oilfield are firstly established by using the drilling, logging, mud logging, and testing data, and the necessary setting points and risk points of geology and engineering are determined. Then, considering the level of drilling technology and the requirements of drilling and completion, the optimization and expansion scheme of casing program is formed. Finally, combined with the drilling parameters, the feasibility analysis of casing program in terms of casing string design, drilling tool strength verification, hydraulic simulation, well control risk assessment, drilling time and drilling cost is discussed. The analysis results show that the optimized casing program can effectively seal the local high-pressure brine developed layer, solve the problem of “overflow, lost circulation and collapse”, reduce the downhole problems, and shorten the drilling time by 20 ~ 25 days and save 2 ~ 3 million per well. The investigates indicate that the optimization of the casing program not only effectively makes up for the shortcomings of the current casing program, reduces the drilling risk, and improves the drilling efficiency, but also provides an important reference for the drilling engineering design of the Fuman oilfield.