The concept is also expected to provide solutions for cost efficient drilling, especially for sub-sea wells. The concept has special advantages for improved downhole pressure control, and for safe and efficient drilling of reservoirs with challenging pressure zones. The concept is suited for drilling with a liner, which optionally can be expanded in place in the same run. A sliding piston in the annular downhole section of the well, is used for force and pressure control. The patented concept is based on the use of a dual channel drill string, where one of the channels is used for the return flow from the well. Therefore, this method can afford an effective approach to improve ROP in deep well.Ībstract The feasibility of a new concept for drilling and lining of a well has been investigated. Through the application of the proposed method, the results show that the ROP in deep and ultra-deep well has been improved obviously, and which have decreased the cost of drilling operation greatly. The results show that the ROP of these wells were improved about 10.5%~80%. Based on the novel and systematic method, the optimal drill assembly, flow rate, pump pressure, nozzle combination and others drilling parameters were all obtained. The technology has been applied in several wells in Tarim basin of China and the test formations are about 3535m-6935m depth. Moreover, for maximizing the ROP, the size of drill pipe size was considered during the process of hydraulics optimization. For improving the design precision, the flow channel both in pipe and annuli was divided into several sections and the flow regime change of each section was considered.
Second, according to the problem that no single rheology model can describe exactly the rheological properties of all types drilling fluids, a systemic hydraulic optimization approach was established, which is applicable for all common rheological models. In order to eliminate the influence caused by the difference of the other drilling data, all of them were normalized in this process. It can conduct the integrated hydraulics design to improve ROP not only during making the drilling design, but also can generate recommendations of hydraulic optimization for improving ROP in the process of drilling based on the real-time drilling situation.įirst, this paper presents a mathematical analysis of the hydraulics (Bit pressure drop, bit specific hydraulic horsepower, et al.) influence on the ROP based on the drilling engineering data of several wells of Tarim basin in west China. A comprehensive procedure of optimization hydraulic design for improving ROP was formulated. Abstract With the oil and gas exploration and development in deep formation and the number of deep wells grow continually, the ROP decreases greatly and the cost of drilling operation increases rapidly.
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