SINOPEC has constructed the first commercial and scaled development shale gas field in Fuling of China, the annual productivity of which is 5 billion cubic meter until the end of 2015. And the other 5 billion cubic meter annual productivity construction of this shale gas field is in progress. The problems faced in this location are the complex geological environment, mountainous environment, the shale gas reservoir characteristics and the reservoirs buried so deeply (vertical depth>3000m). Therefore, the mud loss collapsing and gas kick are very common problem encountered while drilling, the ROP decreased greatly and the cost of drilling operation increase rapidly. With falling oil and natural gas prices, greater efficiency and excellence in well construction is called for, the optimal and fast drilling technology and successful application for shale gas horizontal well in Fuling is described.
Firstly, a "mountainous well factory" design method for shale gas horizontal well design was established, in which the terrain and geography condition, the well trajectory control capacity and the limit of horizontal extension were all taken into account, through which the design of batch operation scheme and optimal well patterns can be obtained easily. Secondly, for improving the productivity of single well and reservoir rate of drilling, a borehole trajectory design model was developed based on the natural drift law of the formation, in which the anti-collision was took into account, and through which all of the optimal trajectories for entire horizontal well group can be designed easily. Moreover, an integrated optimal and fast drilling technology that combined bits optimization, trajectory controlling and BHA optimization was developed based on the analysis of formation characteristic, based on which the best drilling optimal plan can be formulated.
The optimal and fast drilling technique has been applied in several mountainous well factory platform in Fuling shale gas field of SINOPEC. And through the novel technology for shale gas horizontal well group, the drilling show that the ROP of these wells were improved about 182%, the drilling cycle were cut down more than 50% and the cost of well construction was decreased more than 30%.
This study will presented the novel optimal and fast drilling technology for shale gas horizontal wells, which includes the mountainous well factory design method, the improved well trajectory design and control method, and the novel technology application in shale gas drilling design and construction. Through the application of the optimal drilling technology, the results show that the ROP in shale gas horizontal well drilling has been improved obviously, the drilling cycle and the cost of well construction was decreased greatly.