Analysis of Fracture Fluid Cleanup and Long-term Recovery in Shale Gas Reservoirs

Open Access
Author:
Seales, Maxian Burton
Graduate Program:
Petroleum and Natural Gas Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
April 22, 2015
Committee Members:
  • Yilin Wang, Dissertation Advisor
  • Yilin Wang, Committee Chair
  • Turgay Ertekin, Dissertation Advisor
  • Christopher Gorski, Committee Member
  • Antonio Nieto, Committee Member
Keywords:
  • Shale Gas
  • Fracture Fluid Cleanup
  • Dual Porosity
  • Flowback water composition
Abstract:
Horizontal wells combined with successful multi-stage hydraulic fracture treatments are currently the most widely applied technology for effectively stimulating and enabling economic development of gas bearing, organic-rich shale formations. Fracture fluid cleanup in the stimulated reservoir volume (SRV) is critical to stimulation effectiveness and long-term well performance. However, if the created hydraulic fractures and reinitiated natural fractures are not cleaned up, post-fracture well performance will fall below expectations. Flowback water typically has 10 to 20 times more total dissolved solids (TDS) than the injected fluid. The total dissolved solids in flowback water can be as much 197,000 mg/L; chloride levels alone can be as high as 151,000 mg/L. Effective management of waste water produced from shale gas wells requires a clear understanding of how the volume and composition of this water change over the long term, not only during the flowback period. A systematic study of the factors that hinder fracture cleanup, those that influence the ionic composition of flowback and produced water, and those that enhance gas recovery can help optimize fracture treatments, better quantify long term volumes of produced water and gas, and aid with the management of waste water. To this end, a fully implicit, 3-dimensional, 2-phase, dual-porosity numerical simulator was developed and coupled with a ionic composition model. The research findings have shed light on the factors that substantially affect efficient fracture fluid cleanup and gas recovery in gas shales, and have provided guidelines for improved fracture treatment designs and water management.