How to Add Value to Tight Rock Fracturing Stages Using Geologically Constrained 3-D Fracture Models and Microseismicity

Daniel, Jean-Marc; Delorme, Matthieu; Kada-kloucha, Chakib; Khvoenkova, Nina; Schueller, Sylvie; Souque, Christine

In the recent years the rapid development of new plays in tight rocks, more particularly unconventional reservoirs, has promoted innovative technologies and workflows to tackle new production challenges. This has led in particular to the acquisition of a large amount of microseismic surveys to monitor fracturing jobs. With increasing experience, looking at the distribution of microseisms and focal mechanisms in different shale gas/oil basins, it becomes clear that pre-existing weaknesses such as natural fractures and bed boundaries are reactivated during fracturing jobs. This strongly calls for the use of Discrete Fracture Network in workflows designed to simulate the production of unconventionals. The objective of this presentation is twofold. First we describe a workflow based on the use of DFN to simulate fracturing jobs and their related microseismicity. Then from its application, we will discuss how it gives additional values to data collected before and during fracturing jobs.

We first emphasize how to integrate all available data (logs and seismic data) to build a geologically consistent DFN representing the natural fracture network around the wells. We then introduce an innovating mesh of the DFN, allowing to simulate efficiently fluid flow on the large 3-D DFN representative of the geological complexity. These simulations are explicitly coupled to a simplified hydro-mechanical model to compute the effect of fracture reactivation on fracturing stages. This allows confronting models with microseismicity and pressure monitored during the injection period.

From this confrontation on representative cases, we demonstrate how the integration of in-situ stress, pressure measurements and microseismics activity can be used to efficiently discriminate between contrasted conceptual models defined by the geologist from the generally scarce available data and how this improves the characterization of tight reservoirs.

These stimulating results are finally used to discuss the remaining gaps in the understanding of this major targets for our industry.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013