New Type Curves for Shale Gas Wells with Dual Porosity Model

Abstract

As interest in exploiting shale gas/oil reservoirs with multiple stage fractured horizontal wells increased, complexity of production analysis and reservoir description have also increased. The main objective of this paper is to present and demonstrate type curves for production data analysis of shale gas/oil wells using a Dual Porosity model.Dual Porosity model is based on Bello and Wattenbarger's (2010) mathematical model where hydraulic fractures act as a secondary porosity system where matrix is the primary porosity system. Samandarli et al. (2011) showed application of this model on history matching and forecasting of shale gas wells with multiple fractures by doing regression on effective fracture and matrix permeability and half length. This type of regression is as rigorous as simulation, however much faster than it. On the other hand for "quick look interpretation" having type curves will make the production analysis even more convenient for practical purposes.With this method production of shale gas/oil well can be matched with developed type curves which vary with effective permeability. Once the production data is matched with one of the type curves, effective permeability and match points are recorded. By using dimensionless equations developed for Dual Porosity model fracture half-length can be determined. In order to use type curves, good estimate for effective porosity and matrix permeability should be predetermined.Type curves developed in this paper were applied to synthetic and field data examples. Early results show that method works well in determining effective fracture half-length which is the most important parameter in evaluation of stimulated reservoir volume (SRV).

Exergy, Energy, and Gas Flow Analysis of Hydrofractured Shale Gas Extraction

“…Some relative advancements in our model are: (1) while in Ref. [40] the system was assumed to be one-dimensional radial, composed of a cylindrical tube with a horizontal well in the middle and a matrix containing fractures surrounding it, our model represents the fluid mechanics in a somewhat more realistic way, as it consists of a rectangular shale matrix and rectangular blocks with hydraulic fractures beside it, with 2D flow in the uniform matrix and one-dimensional flow in the fractures, and (2) we developed a partial differential equation (PDE) system for the model and solved it numerically to get the result, while in Ref. [43], it seems that the governing equations were solved partially by use of a correlations algorithm.…”

“…After hydraulic fracturing, gas starts to flow from the highpressure low-permeability matrix to the formed lower-pressure high-permeability hydraulic fractures. The shale gas reservoir is usually [2,[37][38][39][40][41][42] assumed to be a "dual porosity" system, in which the matrix block and the fractures made in it are characterized by different (but constant) porosities and permeabiliies, treated therefore as two interconnected different porous media. The gas flow through them is typically assumed in the literature to be one-dimensional.…”

“…2.8. The gas flow from the shale matrix is primarily driven by the pressure difference between the matrix, assumed here to be initially at a pressure of 1.72 Â 10 7 Pa, toward the lowest pressure point of the well's horizontal pipe assumed to be at 8.6 Â 10 6 [40]. Figures 6-9 show that the gas pressure in the matrix is being reduced toward larger values of X because the fracture that drains the gas to the well is along X ¼ 1 and the lowest pressure is at the upper right corner (X ¼ 1, Y ¼ 1) where the gas flows from the fracture to the well's horizontal pipe (that is, along Y ¼ 1).…”

A composite dual-porosity fractal model for channel-fractured horizontal wells

“…In recent years, shale oil and gas have greatly contributed to the US energy portfolio and are expected to be the main source of energy within the next 20 years. The majority of commercial production in shale play requires intensive fracturing along with long horizontal well drilling (Abdulal, Samandarli, & Wattenbarger, 2011;Britt & Smith, 2009;Wang & Wu, 2013). As a widespread and effective approach, multi-stage fractured horizontal wells have made oil and gas production more efficient and economical in shale plays.…”

Pressure Transient Behavior of Horizontal Wells Intersecting Multiple Hydraulic Fractures in Naturally Fractured Reservoirs

“…In the first paper published on this subject, de Carvalho and Rosa (1988) used the pseudosteady-state flow conditions in matrix blocks with the s → s f (s) transformation to derive the pressure transient solution for a horizontal well in a naturally fractured reservoir. After the de Carvalho and Rosa (1988) solution, many more solutions have been published in the petroleum literature using the → s f (s) transformation, while varying the matrix block shape and matrix block flow condition, and adding the interporosity skin factor for the matrix (Aguilera and Ng 1991;Du and Stewart 1992;Williams and Kikani 1990), in addition to the more recent papers by Abdulal et al (2011), Brohi et al (2011), Guo et al (2012, Ketineni and Ertekin (2012), Lu et al (2009), Medeiros et al (2007, 2008, 2010, Nie et al (2012a, b), Torcuk et al (2013).…”