Evaluating and Implementing a New Pillar Fracturing Technology Using Local Sand for Proppants in the Middle East

摘要

Using local natural silica sand as a proppant can significantly reduce costs as hydraulic fracturing activities increase in the Middle East. Though natural sand resources in the region are abundant, they are mechanically weaker than the typical prop-pants necessary to fracture deep gas reservoirs. Using chemicals to bind sand grains to form competent pillars within a hydraulic fracture can help sustain conductibility at high closure stress and prevent mobilization of the crushed fines. A laboratory study demonstrated that this approach can generate stable and highly conductive channels with a near infinite fracture conductivity. A field trial of such technology was performed. Careful evaluation was performed on many gas wells to select a candidate based on the plain strain modulus and other petrophysical parameters. Before the primary fracturing treatment, a diagnostic fracture injection test and minifrac were conducted to calibrate rock properties used in the fracturing design. The proppant was placed by pulsed pumping to render proppant pillars of resin bonded local sand. Among the pillars are wide channels through which the reservoir fluid can be effectively produced. The post-fracturing treatment flow back sample analysis showed neither proppant nor fines production. The field test results indicated that this technique, which was being performed for the first time in the Middle East, can be a viable means to enhance productivity in low permeability formations. This article describes the experimental study to evaluate the feasibility of using low-cost raw sand in combination with a pillar fracturing technique to fracture high stress formations. The engineering approach for design, implementation, and assessment of such a technique in a gas reservoir is also presented.