Evaluation Method of Shale Oil Reservoirs Fracability—A Case from Seventh Member of Triassic Yanchang Formation in Ordos Basin 2018 IFEDC

Abstract

Fracability is the capability of the shale that can be fractured effectively during hydraulic fracturing. Now, the fracability evaluation mainly focuses on shale gas reservoirs, and there are few researches on shale oil reservoirs. Taking the seventh member of Triassic Yanchang formation shale oil reservoirs in the Ordos basin as an example, the geological sweet point of shale oil reservoirs is given in the quantitative evaluation of physical property and geological characteristics of shale oil reservoirs. An evaluation method of shale oil reservoirs fracability is developed combining with the fracture index and fracture toughness based on petrophysical experiments and existing well logging data. The evaluation method is applied to more than 10 wells of Chang 7 reservoirs in which fracability profile is established. The results show that the shale oil reservoirs fracability can be accurately evaluated by the developed model which can be used to screen the fracturing engineering sweet spot. The fracture distribution and fracturing effect of each well were evaluated by combining with the fractured profiles and anisotropic production diagrams of pre-frac and post-frac, and the results were compared with the actual fracturing effect of each well. Compared with the adjacent sandstone section, the Chang 7 shale oil reservoir has a lower level of natural fracture development, higher crustal stress and lower brittleness. The study provides a more accurate and effective method for shale oil reservoirs fracability evaluation and engineering sweet spot screening, which will contribute to increase the success rate of fracturing treatments and reduce the blindness of pre-fracture wells selection.

Copyright 2018, Shaanxi Petroleum Society.

This paper was prepared for presentation at the 2018 International Field Exploration and Development Conference in Xi’an, China, 18–20 September, 2018.

This paper was selected for presentation by the IFEDC Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the IFEDC Committee and are subject to correction by the author(s). The material does not necessarily reflect any position of the IFEDC Committee, its members. Papers presented at the Conference are subject to publication review by Professional Committee of Petroleum Engineering of Shaanxi Petroleum Society. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of Shaanxi Petroleum Society is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of IFEDC. Contact email: paper@ifedc.org.