Application of rotary geosteering drilling in deep and thin reservoirs of Tarim Basin, NW China

Abstract

Geological features, such as deep and thin reservoirs and unstable structure margin, occur in an oilfield of the Tarim Basin. To deal with these problems while drilling, a rotary geosteering drilling technique was introduced. The effect of its application was analyzed with an example, the shortcomings were summarized, and suggestions were given for other oilfileds. The feasibility and necessity of using rotary geosteering drilling were presented according to the engineering challenges in the oilfield, then the theory and main tools of it were introduced. Focusing on a double-step horizontal well in field application, the features and effects of this technique were elaborated. With rotary geosteering drilling in this well, the average rate of penetration was high and oil reservoir encountering rate was up to 82% in thin layers less than 1 m. Also, it avoided effortless weight on bit in sliding drilling method and made the wellbore more smooth and clean. The problems met were concluded, for example, the tools build-up rate was affected by several factors, measurement while drilling (MWD) signal was interfered, and the tools working performance was unstable. Suggestions were put forward for applying the rotary geosteering drilling technique in other oilfields. Key words: horizontal well, drilling, rotary geosteering, deep thin reservoir, logging while drilling (LWD)