Technology Focus: Tight Reservoirs (October 2010)

Abstract

Technology Focus Shale-gas reservoirs are becoming an increasingly significant percentage of the global tight-reservoir landscape. Three questions reflect this increasing dominance but are applicable overall to tight formations. Is the long multistage-fractured horizontal well into which millions of gallons of water are pumped downhole with only a third of the contacted reservoir propped open the most efficient way to produce the reservoir? Is the long multistage-fractured horizontal well the endgame solution to Master’s Resource Triangle? If the equations set forth by Darcy and Young/Laplace are valid, does contacting a large amount of the formation with only water constitute stimulation of the reservoir? Capillary pressure is significant in tight reservoirs. Stimulation-fluid invasion into smaller pore diameters and invasion of proppant-free stimulation fluid into both induced fractures and dilated natural fractures will have an effect. Production-decline rates and long-term health of wells (improved fluid flow or degree of formation damage) in tight reservoirs will depend on how capillary forces are managed in the reservoir. Log-normal large volumes of hydrocarbon found in tight reservoirs are difficult to develop because of constrained drainage areas, complicated petrophysics, lithology, and formation heterogeneity. These difficulties, complexities, and heterogeneities dictate planning of drilling, completion, and stimulation specific to the well in question. They also dictate continued advances in knowledge and technology if the majority of the hydrocarbon asset is to be produced effectively. Early production levels will be dependent on the length of propped fracture from the wellbore that has actually cleaned up and this contributing to hydro-carbon flow. Our industry needs to make advances in: real-time measurement; post-fracture monitoring with production analysis; identifying sweet spots, then placing perforations to create complex conductive fractures; innovative proppants and proppant-placement techniques in primary and complex fracture geometries; fluid recovery; formation-damage control and permeability enhancement; proppant transport with less-damaging stimulation fluids; and environmentally responsible drilling, completion, and production services. Tight Reservoirs additional reading available at OnePetro: www.onepetro.org SPE 128191 • “Selecting Drilling Technologies and Methods for Tight Gas Sand Reservoirs,” by Pilisi, N., SPE, Blade Energy Partners, et al. SPE 131778 • “Using Microseisms to Monitor Hydraulic Fractures in the Bakken Formation of North Dakota,” by Gary S. Forrest, Schlumberger, et al. SPE 130043 • “Fracturing Design Aimed at Enhancing Fracture Complexity,” by M.Y. Soliman, Halliburton, et al.