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- Title
致密砂岩气藏水平井多学科综合导向新技术--以鄂尔多斯盆地为例.
- Authors
费世祥; 杜玉斌; 王一军; 陈 楠; 高 阳; 王树慧; 何 鎏
- Abstract
The sandstone layers of the Upper Paleozoic tight clastic gas reservoirs in the Ordos Basin are generally distributed in a pattern of nearly NS strip, and the channel branches and intersects frequently. A single sand body is in a multilayered contact mode resulted from lateral accretion, and the sand bodies at the river intersections present a feature of lying in the nearly EW direction, which brings great difficulties to the geosteering of horizontal wells. In order to improve the reservoir drilling rate of horizontal wells, this paper systematically analyzed the geosteering status of horizontal wells and the sedimentary characteristics of reservoirs. Then, the spatial distribution of reservoirs was predicted using 3D geological modeling and 3D seismic. In addition, based on the cognitions on the space distribution of sand bodies from the drilled horizontal wells, the horizontal-well geosteering technology and method were constantly improved and enriched. Thus, an integrated steering technology of "fine sublayer correlation for target entering, geology in small scale, and seismic in large scale" based on in-depth integration of multidisciplinary thinking was newly formed, and it was also applied on site. And the following research results were obtained. First, under the guidance of the sedimentation model, the target entering process is controlled precisely and the success rate of one-trip target entering is improved, so it is one important method for the target steering of deviated hole sections. Second, geological modeling can guide the drilling of horizontal wells, but to some extent, it is deviated from the real underground geologic bodies, so it can be used as an auxiliary horizontal-well steering method. Third, 3D seismic steering can tell the boundary of complex river channel and discriminate the spatial relative location of predominant sand bodies, so it is the primary method for horizontal- well steering to provide excellent judgement and guidance on the steering of horizontal hole sections. Fourth, owing to the application of this new method in 62 horizontal wells drilled in the tight gas demonstration area, the average horizontal section length reaches 1 430 m, the average sandstone drilling rate is 86.2%, the average gas layer drilling rate is 70.2%, and the gas layer drilling rate of horizontal wells is increased by more than 10%.
- Subjects
GAS well drilling; HORIZONTAL wells; GEOLOGICAL modeling; SANDSTONE; GAS reservoirs; RIVER channels; GEOLOGY
- Publication
Natural Gas Industry, 2019, Vol 39, Issue 11, p58
- ISSN
1000-0976
- Publication type
Article
- DOI
10.3787/j.issn.1000-0976.2019.12.007