A Completions Roadmap to Shale-Play Development: A Review of Successful Approaches toward Shale-Play Stimulation in the Last Two Decades

Abstract

Almost three decades have passed since the early exploration of the north Texas, Barnett Shale. The Barnett serves as an example study for the shale lifecycle. Operators in North America have used the Barnett-shale development as a roadmap for the exploration of new shale plays like the Marcellus, Haynesville, and Eagleford. Each new shale play is unique in nature with respect to geologic setting, lithology, and production mechanism. It is useful to have a defined strategy for the discovery, development, and decline phases of each individual shale play. The roadmap to shale well-completion designs should include the following key factors: Fracability: capability of the reservoir to be fracture stimulated effectivelyProducibility: capability of the completion plan to sustain commercial productionSustainability: capability of the field development to meet both economic and environmental constraints This paper reviews the evolution and development of completion practices of the major USA shale reservoirs in the last two decades and presents a roadmap for effective completion practices for shale stimulation. The completion roadmap uses the history of 16,000 shale frac stages in the Barnett, Woodford, Haynesville, Antrim, and Marcellus shales. Following the map through specific decision points will alter the path for individual shales. These decision points will be influenced by geologic, geochemical, and geomechanical information gathered along the way. The path toward a commercially viable shale play from the early asset-evaluation phase to late asset maintenance-and-remediation phase evolves from a series of decision trees throughout the process. Information presented in this paper provides a completion engineer with better understanding of the factors involved in shale-play stimulation and provides a methodical approach to select appropriate and optimum solutions that have evolved during the last two decades.

Numerical Investigation of Fracture Compressibility and Uncertainty on Water-Loss and Production Performance in Tight Oil Reservoirs

“…The following empirical exponential formulas Equations 5and 6are used to describe the variation of porosity and permeability with the pressure in fracture system to realize the actual pumping rate and time [36,53]: In Equations (5) and 6, φf is current fracture porosity; φf0 is original fracture porosity; Cfi is the fracture compressibility during injection, KPa −1 ; Pnet is net pressure within fractures (difference between original pressure and current pressure), KPa; kf is current fracture permeability, md; kf0 is original fracture permeability, md; mi is the permeability changing factor, KPa −1 (exponent empirically determined). Tiab et al [54] reported that the fracture compressibility was as much as two orders of magnitude higher than the matrix compressibility.…”

“…In the process of stimulation, hydraulic fractures may connect and reactivate the already existing natural fractures or generate new induced fractures near the wellbore. Well productivity could be substantially increased if complex fracture networks are created by hydraulic fracturing [4,5].…”

“…Different from conventional fracturing, slickwater is the most commonly used fracturing fluid in unconventional reservoirs. Slickwater has a relatively low cost and low viscosity, which may help to create complex fracture networks [5][6][7]. Horizontal wells that undergo multi-stage fracturing operations often require a large amount of water injected into the formation to create a large stimulated reservoir volume.…”

Pore‐scale modeling of hydromechanical coupled mechanics in hydrofracturing process

“…Consequently, it is of great necessary to explore the relationship between rock mass properties and the hydraulic fracture geometry, so that we can predict what kind of fracture geometry tends to be generated in a specific reservoir. Recently, some rock properties such as brittleness [Chong et al, 2010] and geologic discontinuities [Warpinski and Teufel, 1987] have been studied, but the effect of the strength heterogeneity, a common but essential feature in rock, on the fracture geometry has not been fully investigated especially quantitatively. Thus, we attempt to bridge this gap with current simulation.…”

Using water‐miscible nonionic hydrophobic monomer associating HPAM as drag reducing agent

“…In the reservoir renovation process, slick‐water, which contains a small amount of modified polyacrylamide (drag reducing agent, DRA), is a preferred candidate for shale gas fracturing due to its cheap price and highest suitability . In particular, drag reduction (DR) performance is one of the basic features of slick‐water, so it is important to choose or synthesize a DRA with good DR performance in field applications.…”