Research And Field Application Of Directional Well Composite Drill Bit Technology

With years of continuous exploration of oil and gas, the resources in shallow reservoirs is decreasing gradually. The use of directional and horizontal wells can effectively improve the exploration efficiency and reduce the drilling cost. As a result, application of directional and horizontal wells is gradually increasing in drilling engineering. There are two methods in building directional wells:rotary steering and slide steering. With the advantages of simple structure and low cost, slide steering has hold the dominant position in building directional wells.A major problem for slide steering is the unstable tool face in the kick-off section. For the existing PDC bits, the large operating torque and high torque response for its working mechanism bring unmanageable tool face and unstable steer performance for it. For a roller cone bit, the steer performance is better, but its penetration rate is too low. For the composite drill bit which combines advantages of PDC and roller cone bits, it works efficiently in both hard and multi-interbedded formation. Moreover, low torque and high ROP enables the composite drill bit to get great performance in directional well. Though a series of studies on the composite bit has been conducted in this field, they are mainly concentrated on drill bits drilling hard formation. Study on the composite bit for directional well is still on the primary stage, especially on directional performance and design theory of the drill bit. Study on composite bit for directional well is conducted in this article, which including:1. Study on the directional performances of the roller cone bit, PDC bit and the composite drill bit, and analysis on the primary causes of the differences in tool face stability between the cone bit and PDC bit. Furtherly, the calculation model of the torque of composite drill bits are established, and the factors influencing the directional performance of the bits, as well as the influencing law, is revealed through indoor experiments.2.Research on the design methods of composite bit applied for directional wells, including cutting?gage and hydraulic structures of the bit.3. In accordance with the well structure and formation features of the directional wells in Jidong Nanpu oil field, two types of composite bits are designed and manufactured to conduct a series of field tests, and the test results proved the advantages of the composite bit.