Browsing by Author "Verma, Rahul"
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Item Hydraulic fracturing sand resource development in the Llano uplift region, central Texas : resource calculation, favorability analysis, and transportation economics(2016-05) Verma, Rahul; Elliott, Brent Alan; Kyle, James Richard; Gutierrez, GenaroUse of naturally occurring sand, one of the most commonly used proppants for hydraulic fracturing, has grown tremendously as a commodity in the past decade as hydraulically wells for petroleum production from unconventional reservoirs increased significantly. USGS estimates that the United States produced more than 94 million metric tons of industrial sand in 2015, almost 52 percent of the global production. About 71 percent the total industrial sand was used for hydraulic fracturing and well packing in 2015. With the recent decline in oil and gas price and exploration drilling, it becomes all the more relevant to develop low cost, locally extracted sand for hydraulic fracturing. The Hickory sandstone unit of the Riley formation in central Texas is one such resource. The region is already one of the largest sand producers in the US and is conveniently located within 200–300 miles of major shale basins in Texas. Barnes and Schofield (1964), and Kyle and McBride (2014) present geological studies of the region and its potential for hydraulic fracturing sand. This study builds on this experience, to calculate for the first time, the total resource volume in the region. Benson et al. (2015) considers high friability, near surface access and proximity to transportation facilities as the three most important qualities of sand resource. As the sand in the Llano uplift region was never buried more than 1,500 feet, it remains friable (Kyle and McBride, 2014). This study estimates the sand resource in the Llano Uplift region to be more than 24 billion metric tons, of which, 20 billion metric tons is characterized by near surface access and proximity to transportation facilities. Several favorable sites for extraction are identified in Mason County, McCulloch County, San Saba County, Barnet County, and Llano County. Several hydraulic fracturing sites in the Barnett, Eagle Ford, and Permian basin, with fracture closure stress less than 6,000 psi, are identified as potential markets for the sand extracted in the Llano Uplift. A transportation cost optimization between using railways and highways, to transport sand from favorable extraction sites to hydraulic fracturing sites, finds that using highways is most cost effective means for transporting to all the sites in the Permian basin, most sites in the Barnett basin, and a few in the Eagle Ford basin. A combination of railways and highways is found to be more cost effective on a few routes to the Barnett and Eagle Ford basin.Item Validation of level set contact angle method for multiphase flow in porous media(2014-12) Verma, Rahul; Prodanović, MašaPore-scale simulation has become increasingly important in recent years as a tool to understand multiphase flow behavior. Wettability affects aspects of flow such as capillary-pressure saturation curves, residual saturation of each phase, and relative permeability. Simulation of wettability at the pore-scale is still a non-trivial problem, and many different approaches exist to model it. In this work, we implement a variational level set formulation to impose different contact angles at the solid-fluid-fluid contact line for two-phase flow in simple rhomboidal pore geometries, and calculate the maximum mean curvature (equivalently capillary pressure) for each case. We compare our results with a detailed set of analytical and experimental results in a range of pore geometries of varying wettability from Mason and Morrow (1994), and demonstrate the accuracy of this method. While the simulations shown are for relatively simple geometries, the method has the ability to handle arbitrarily complex geometry (such as input from X-ray microtomography imaging).