Directional wells and cluster wells have become a conventional drilling technique now, which is widely used in various types of oil and gas reservoirs. Each year, more than half of the total drilling are directional wells in China. The main work is not to aim the target area, but to track the reservoirs now. Geosteering drilling is an important technical approach to improve single-well production and recovery ratio, to achieve the “less wells more production” idea.

China Geosteering Drilling System (CGDS), integrated the technology of drilling with logging and reservoir engineering, applies the near-bit geological and engineering parameters as well as controlling method to ensure that the wellhole trajectory can pass through reservoir and get best location while drilling. The wellhole trajectory can be adjusted and controlled timely according to the formation features measured by CGDS. The drilling bit is equipped with “eyes”, which can identify oil/gas layer during drilling.

Since 2011, we have provided CGDS geosteering services in 29 horizontal wells in Songliao Basin. The total footage reached 18255m, and the longest footage in horizontal section was 1325m in single well, while the average sand penetration rate is above 85%. Comparing with the horizontal wells operated by conventional LWD tools in the same block, the results of the field application shows that the CGDS geosteering system can significantly improve sand penetration rate and substantially reduce the drilling duration.

On the basis of introduction to the system, this paper focuses on comparative analysis of significant application effect of CGDS geosteering system for the heterogeneous reservoir in Putaohua Area of Songliao Basin, as well as the lessons learned. Helpful case histories will also be presented.

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