Casing program optimization of deep wells in the central Bohai area

In the drilling process of deep wells, it is necessary to isolate the formations with different pressure systems and the complex formations. And casing program is an important influential factor to ensure the drilling of target layer fast and optimally. In this paper, the optimized design process of casing program was analyzed by taking the deep well in the central Bohai Block as an example. The predrilling pressure prediction model was updated continuously in real time by means of multi-source data fusion technology, based on geological analysis and real-time data of logging while drilling of the deep layers in the central Bohai area, so that the obtained predrilling pore pressure is more accurate. Then, the casing program was optimally designed according to geological characteristics, well control and three-pressure profile, and the original six-section hole structure was optimized into the five-section by reducing the number of technical casing layers and optimizing the casing setting depth. Thus, a set of casing program suitable for this area was developed. This technology can effectively avoid the complex accidents that may occur in the process of operation under the premise of ensuring the drilling safety, so as to reach the target of shortening the drilling cycle and improving the rate of penetration (ROP). And it can also provide references for the casing program design of offshore deep drilling operation in the following step.