Research and Application of Speed-up Technology of Screw Motor Combined with Composite Impactor in Block L of East China Sea

The drillability of Block L in East China Sea of CNOOC is poor. There are large sections of pebbly medium sandstone and sandy conglomerate in Oujiang Formation, and the footage of a single bit is short. Lingfeng Formation is dominated by mudstone and silty mudstone, which makes it difficult for bits to eat and causes low rate of penetration (ROP) and long borehole immersion time. It is prone to complex situations such as drilling tool obstruction and sticking. In order to improve the drilling efficiency, shorten the drilling cycle and accelerate the exploration and development process of oil and gas fields in Block L, the practical exploration of drilling speed was carried out. After summarizing and analyzing the current situation of drilling speed-up in Block L, this paper comprehensively considers the working principles of two different types of speed-up tools: screw motor and composite impactor, innovatively explores the matching use of screw motor and composite impactor, and strengthens bit aggressiveness and tooth arrangement technology. It is applied to the gravel layer of Oujiang Formation and mudstone section of Lingfeng Formation in Block L direct exploration well, with remarkable speed-up effect. The problems such as short footage of a single bit, serious wear and tear, low mechanical penetration rate and difficult to control well deviation in this block have been well solved, the record of the longest footage of a single bit in this block has been set, and the one-time drilling project of 12-1/4″ borehole has been realized. It can be popularized and applied in direct exploration wells in similar areas.