Real-Time Integrated Optimized Drilling Technology for Deep Carbonate Formation

Abstract

Abstract For deep carbonate formation, there are many drilling problems in applications, such as hydrogen sulfide distribution, narrow pressure window, strata complex, objective layer pressure sensitive, which lead to drill ahead and improve the rate of penetration (ROP) very difficultly. And carbonate reservoir comprises many fractures and caves which must be connected as more as possible to form a longer petroleum channel for increasing single well production. In order to solve above problems, an integrated optimized drilling technology is raised to realize these challenges which includes three important points of innovation. Firstly, it is the horizontal well optimized design along top boundary of fracture-vuggy formation to realize the longest horizontal section because of petroleum inside fracture or vuggy. Secondly, it is to increase ROP by minimal mechanical specific energy and micro underbalanced pressure drilling method to optimize drilling parameters. Thirdly, it is to develop managed pressure drilling (MPD) in complex conditions to monitor annular pressure in real-time and keep downhole pressure constant or whole circulation flowrate stable. The new design can help us get more opportunities to increase the production of single well effectively. The real-time integrated control method can realize ROP significantly, such as get about 39% improvement than before in Tarim oilfield. If no harmful gas or a little harmful gas come out from formation, micro underbalanced pressure control drilling technology may be most applicable method to develop deep carbonate formation because it can control well kick at a small rate to find pay zone, keep well wall stable and improve ROP. In sum, after many field applications in deep carbonate formation, it is proven that the integrated optimized drilling technology can break through the traditional drilling technology to extend horizontal section as long as possible (present record of longest horizontal length is 1561m), find more pay zones and overcome the drilling problems in deep carbonate formation to realize safety and fast drilling and gain maximal economic benefits. In contrast to conventional real-time control method, the new technology considers the design about how to extend the horizontal section length along the top of frature-vuggy structures which is safety and effective in reality. At the same time, we adopt new real-time parameters optimization and managed pressure drilling to solve different problems and also improve drilling effect. Therefore, especially for deep carbonate formation development, the new real-time optimized integrated drilling technology should be gotten more and more applications for develop effectively.