Geology-engineering integration solution for tight oil exploration of Chang-7 member, Ordos Basin—focusing on scientific well spacing and efficient drilling
【Abstract】The tight oil reservoirs of the Chang-7 member in the Longdong area, Ordos Basin, are mainly gravity flow sand bodies. The distribution of sand bodies is complex in both vertical and lateral directions, and the thickness of a single sand body is low, which poses a challenge to efficient drilling and production. In this paper, a set of geology-engineering integration methods is proposed, which combines multi-disciplinary knowledge such as near-bit measurement while drilling (MWD) technologies. On the basis of comprehensive geological research, 3D fine geology, reservoir, and geomechanics models are established for selection of well locations, design of factory-like platforms, drilling operations and optimization of geo-steering schemes, so as to design well trajectory scientifically and reasonably, enhance the penetration rate of the sand body during drilling, and ensure higher single well production in later production stage as well as the ultimate long-term accumulative production of the well block. The results show that high-quality reservoirs in the study area are mainly massive clastic-flow sandstones. And the key to improving penetration rate is to use the real-time transmission MWD data, and comprehensively analyze the drilling, well logging and mud logging data to determine the accurate bit location in the sedimentary cycle, so as to determine the geo-steering operation scheme. Under the guidance of this method, two horizontal wells are drilled, whose penetration rates of oil layers are 5%–10% higher than that of the surrounding wells. According to the early-stage numerical simulation based on geology and geomechanics models, combined with scientific well spacing during drilling and production practice, the optimized horizontal well spacing in the study area is finally defined as 400 m.
【Keywords】 Ordos Basin; tight oil; geology-engineering integration; geo-steering; geology modeling;
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