Hydraulic Fracture Geometry Investigation for Successful Optimization of Fracture Modeling and Overall Development of Jurassic Formation in Western Siberia

摘要

The focus of our research is on a remote oilfield in western Siberia, currently in the initial stages of development. There are two producing horizons of Jurassic age with a shale barrier in between them and variable oil/water contact (OWC). Each new well of the field is a candidate for a hydraulic fracturing treatment. Depending on well location, there is an option to perform the fracturing treatment on the lower formation only, the upper formation only, or to conduct two separate fracturing operations. Fracture breakthrough on any of the jobs can lead to significant production underperformance. With a goal to calibrate fracture modeling and identify the most critical parameters for fracture treatments, the decision was made to implement an independent measurement of frac geometry for an ongoing fracturing campaign. A total of 11 fracturing treatments are described in detail where differential cased-hole sonic anisotropy (DCHSA) measurements as well as bottomhole pressure gauges (BHPG) were implemented to enable precise modeling and to determine reliable fracture geometry. DCHSA, using a dipole shear sonic imager tools, allows for direct measurement of propped fracture height and fracture orientation azimuth. Provided with fracture height and using bottomhole pressure data, it was possible to accurately model resulting fracture half-length and propped width. In addition to DCHSA measurements, a study to describe the geomechanical properties of the formations was also undertaken to further enhance the understanding of fracture height growth in the reservoirs. Advanced open-hole logging was performed on four wells, which served as the basis for creating a geomechanical model for other wells in the field. The methodology used to model stress distribution from acoustic logging was developed using a correlation created from density logs run on offset wells. This tool allowed for reliable fracture modeling at the design stage, and enabled optimization of fracture treatments. By coupling the enhanced geological understanding obtained from the fracturing campaign with advanced geometry measurement technology, an effective geomechanical modeling method was successfully applied for future field development and production optimization. This research's technical workflow can be used as a comprehensive guideline in any field where precise placement of hydraulic fracture makes a significant difference in the overall development of a field.