Solutions for Better Production in Tight Gas Reservoirs Through Hydraulic Fracturing

Abstract

The challenge to make best producers for the least investment in tight gas reservoirs has always been with the oil and gas industry since production in many tight gas reservoirs is oftentimes marginal, at best. This paper presents solutions for better production in tight gas reservoirs through hydraulic fracturing. Properly engineered hydraulic fracture treatments are enablers to achieve overall economies of scale with development of tight gas reservoirs. These treatments are conducted to bypass completion damage and stimulate production from low permeability reservoirs. They are designed using simulators with a range of capabilities in an effort to maximize the economic benefit of the treatment, effective fracture length, and number of zones producing, fracture conductivity, acceleration of recovery, addition of reserves, and minimize job failures and treatment costs. To accomplish these goals, substantial amount of information is required to describe reservoir flow capacity and provide the data needed to predict treatment pressure response as well as fracture geometry and conductivity. These data will determine the optimum size of the treatment, the maximum proppant concentration that can be pumped, and the expected production response to the stimulation. When sufficient input data are available to characterize the reservoir, the fracture geometry can be accurately modeled with a capable simulator, the treatment goals listed above can be realized and an optimum design can be reached. The design process, including selection of proppants and fluids, pumping schedule, injected proppant concentrations, total job size, pump rate, and other parameters requires an idea of the desired outcome of the job: required fracture length, possible pack concentration and clean-up time. Critical measurements from testing of actual cores has allowed to sift through the chaff to find those "gems" in hydraulic fracturing that materially improve the completion efficiency in tight gas reservoirs. Introduction A definition of tight gas reservoir is "a reservoir that cannot be produced at economic flow rates or recover economic volumes of natural gas unless the well is stimulated by a large hydraulic fracture treatment or produced by use of a horizontal well bore or multilateral well bores."4 The major unconventional gas reservoir types include tight reservoirs, CBM, shales, and hydrates. Tight reservoirs are most important in terms of production (15.6 Bcf/D in U.S., 4 Bcf/D in Canada representing some 25% of Canadian Production)1. To some degree, there has always been production from unconventional reservoirs in virtually all North American basins in the United States such as Rocky Mountains, South and East TX, north LA, Mid-continent, Appalachia, Jonah/Pinedale, Natural Buttes, Wilcox Lobo, Cotton Valley/Travis Peak, and Clinton/Medina.

Simulating Hydraulic Fracturing in Real Fractured Rocks - Overcjavascript:iterm()oming the Limits of Pseudo3D Models

“…They found that high flow rate or high viscosity created fluid-driven fractures while low rates tended to open the existing NFR. These findings were echoed by Arukhe et al, (2009) who found that many mechanisms contributed to the final created fracture geometry during a hydraulic fracture stimulation including pump rate, viscosity, and proppant scheduling. Damjanac et al, 2010 presented the results of hydraulic fracture modeling in an NFR with a discrete element model (DEM) in which they highlighted the impact of fluid compressibility on hydraulic fracture geometry (a very compressible fluid created a more complex fracture geometry).…”

Integrating Solid Expandables, Swellables, and Hydra Jet Perforating for Optimized Multizone Fractured Wellbores

“…Critical measurements from testing the actual cores has allowed to sift through the chaff to find those "gems" in hydraulic fracturing that materially improve the completion efficiency in tight gas reservoirs. (Arukhe 2009) Develop the Wellbore to Match the Reservoir Potential -"Rightsizing" Solid expandable technology provides the means to establish the largest possible reservoir wellbore to support any type of perforating/fracturing technique without sacrificing maximum stimulation programs, production pathway or future re-entry requirements. The real value added is from the overall wellbore construction.…”

“…To some degree, there has always been production from unconventional reservoirs in virtually all North American basins in the United States such as Rocky Mountains, South and East Texas, north Louisiana, Mid continent, Appalachia, Jonah/Pinedale, Natural Buttes, Wilcox Lobo, Cotton Valley/Travis Peak, and Clinton/Medina. (Arukhe 2009) Estimates of shale gas in the US range from 500 to 1,000 Tcf, while the Gas Technology Institute calculates ~780 Tcf. The US Energy Information Administration estimates that US shale's contain 55.42 Tcf in recoverable gas.…”

Verification of Coupled Hydraulic Fracturing Simulators Using Laboratory-Scale Experiments

“…Over the past few decades, the technique of hydraulic stimulation has received considerable attention in both renewable and fossil energy sector. Advancements in hydraulic stimulation technology have not only elevated the estimates of energy production from tight gas reservoirs (Arukhe et al 2009) or Enhanced Geothermal Systems (EGS) (Brown et al 2012), but also has important implications for managing CO 2 storage performance (Fu et al 2017). In the field of geothermal energy, hydraulic stimulation is employed for permeability enhancement, in otherwise low porous and low permeable rocks, whereby, fluid is injected at high pressure into the deep-seated, hot and dry rocks activating the natural fracture network or creating new fractures.…”