The concept of SRV was supposed to represent the reservoir volume affected by the fracing and the proppant placement but end up being used as the microseismic stimulated reservoir volume which is usually a much larger volume. Given this large difference, many authors resorted to creating new concepts of SRV adapted to the problems at hand mainly the estimation of reserves. Most of these new concepts rely on the use of microseismic which still has a lot of issues to resolve before being a standard input in shale reservoir simulation and reserve estimation.

To reduce our dependence on microseismic data which is only available in about 5% of the shale wells, a new workflow based on "hard" G&G data is introduced for the estimation of SRV and its varying rock properties in a reservoir simulator. This new workflow relies on the use of the concept of Shale Capacity which encompasses the four key shale drivers responsible for most of the factors affecting the shale well performance: TOC, Brittleness, Fracture Density and Porosity. The shale capacity is available over the entire 3D reservoir volume and is estimated from well and seismic data.

The SRV varying enhanced permeability is estimated through a linear relationship that links the well test measured (PTA or RTA) permeability with the shale capacity thus providing realistic values to the reservoir simulator. Using appropriate gridding techniques such as the Tartan grid for the SRV cells, nearwellbore effects could be accounted for along with no Darcy effects and gas desorption in the shale reservoir. With these key factors represented in the dynamic model around the well, a Marcellus gas and water rate was successfully matched without the need for any major history matching effort. The resulting gas saturation and pressure distribution indicate that the naturally fractured shale matrix cells do contribute to the reserves which are not limited to the nearwellbore SRV cells where the proppant was successfully placed.

You can access this article if you purchase or spend a download.