Summary The application of horizontal-well drilling and multistage fracturing has become a norm in the industry to develop unconventional resources from ultratight formations. A complex fracture network generated in the presence of stress isotropy and pre-existing natural fractures immensely extends reservoir contact and improves hydrocarbon production. A semianalytical method is presented in this paper to simulate the production from such a complex fracture network. This method combines an analytical reservoir solution with a numerical solution on discretized fracture panels. The mathematics is briefly introduced. Numerous case studies are presented, from a simple planar fracture to a real-field example from the Barnett shale. Production behavior and the key flow regimes are discussed. With its simplicity, yet capturing the physics of the transient-production performance, this approach provides an accessible tool for people from multiple disciplines in unconventional-resource development to rapidly evaluate treated-well productivity and stimulation effectiveness.

In this paper, we develop a simple, closed form approximation for the Laplace transform solution for the case of a well with a finite cond!Jctivity .ve~cal fracture in an inf~te-acting reservoir. Our hybnd solution IS based on a coupling of the solution for a trilinear finite conductivity vertical fracture model (which does not model radial flow) and the solution for a uniform flux/infinite conductivity vertical fracture (which does model pseudoradial flow). These solutions are readily obtained from the literature. Overall, we considc:r ou~solution to be valid for CjD~0.5 and we show that our solution gIves less than 1 percent error in both PD an~PD' for CfD..>2. We suggest that our hybrid solution is not valid for CfD

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractNew analysis procedures are presented for analyzing the production data of fractured wells in low permeability reservoirs to quantify estimates of the reservoir effective permeability, effective fracture halflength, and average fracture conductivity. The rate-transient based analyses reported in this paper have been used to analyze the production performance of over 200 wells in low permeability reservoirs in North America.Direct comparisons of the fracture properties resulting from conventional crosslinked fluid fractures and low viscosity base fluid ("Water-Frac") treatments in direct offset wells clearly demonstrates that more effective fractures are created in low-permeability reservoirs using the higher viscosity fracturing fluids and large proppant volumes to achieve higher conductivity fractures with greater effective halflengths than are achieved with "Water-Fracs" with little or no proppant.

The application of horizontal well drilling and multi-stage fracturing has become a norm in the industry to develop unconventional resources from ultra-tight formations. A complex fracture network generated in the presence of stress isotropy and pre-existing natural fractures immensely extends reservoir contact and improves hydrocarbon production.A semi-analytical method is presented in this paper to simulate the production from such complex fracture network. This method combines an analytical reservoir solution with a numerical solution on discretized fracture panels. The mathematics are briefly introduced. A number of case studies are presented, from a simple planar fracture to a real field example from the Barnett shale. Production behaviour and the key flow regimes are discussed.With its simplicity, yet capturing the physics of the transient production performance, this approach provides an accessible tool for people from multiple disciplines in unconventional resource development to rapidly evaluate treated-well productivity and stimulation effectiveness. * ECLIPSE Coal Bed Methane Template Training Material, Schlumberger

Several works have tried to address hydraulic fracturing treatments using a unified theory approach based on the dimensionless productivity index concept. The observations and recommendations from these works are based on numerical simulation, resulting from single phase liquid and simplifications such as steady state or pseudo steady state conditions. However, the behavior in the reservoir is not a simplified one and the assumptions made previously by other authors limit the application of the technique. In this paper we present the correct and rigorous mathematical solution of the dimensionless productivity index. The application of a General Expression for Dimensionless Productivity in Bounded Reservoirs is presented and applied to multiwell systems Field examples and results are presented, where production analysis suggested changes and optimization of fracturing fluids, breakers, job sizes, designs, types and mass of proppant, etc. Guidelines for performance optimization and practical standards are obtained from field production results and are also presented. A General Expression for Dimensionless Productivity In this section we present the derivation of a general expression for the Dimensionless Productivity index. To do this, we need to understand the relation between steady state and pseudo steady state conditions in a bounded reservoir. As demonstrated by Poe[1], one of the fundamental inequalities that is applicable for the pressure and rate-transient behavior for all well types and flow regimes, including steady state and boundary-dominated flow in closed finite reservoirs, given by (1) It can be proved that for all flow regimes and well types, for a given tD (tDA, tDXf), the reciprocal of the wellbore rate-transient solution is greater than or equal to the corresponding pressure-transient solution. Equation 1 is the fundamental relationship between the reciprocal of the dimensionless wellbore rate-transient solution and the corresponding dimensionless wellbore pressure-transient solutions. In particular and only for steady state conditions, (constant pressure outer boundary conditions), the pressure and rate-transient behavior are given by