Application of New Drilling Speed-increasing Technology in Paleogene Strata in Eastern South China Sea

The deep Paleogene strata such as the Enping Formation and Wenchang Formation in the eastern South China Sea are highly compacted, with high rock compressive strength, more hard interlayers, and poor drillability. A series of problems such as bit entry difficulty, low speed, serious drilling bit wear, and high frequency of tripping have restricted drilling efficiency and drilling cost. Taking a block in the eastern South China Sea as an example, through summarizing the effect of conventional drilling bits in the past and analyzing the drillability of formations comprehensively, this paper optimizes a set of high-speed drilling technology with a composite impactor and a special PDC bit combination, and carries out field application and verification in difficult-to-drill formations of deep Paleogene. Compared with the drilling speed-up technology of adjacent wells at the same vertical depth and at the same horizon, the ROP and the drilling efficiency has significantly been improved. The successful application of this drilling speed-up technology can provide technical reference for the subsequent speed-up and efficiency improvement of similar difficult-to-drill formations.