A hybrid-hydraulic-fracture (HHF) model composed of (1) complex discrete fracture networks (DFNs) and (2) planar fractures is proposed for modeling the stimulated reservoir volume (SRV). Modeling the SRV is complex and requires a synergetic approach between geophysics, petrophysics, and reservoir engineering. The objective of this paper is to characterize and evaluate the SRV in nine horizontal multilaterals covering the Muskwa, Otter Park, and Evie Formations in the Horn River Shale in Canada, with a view to match their production histories and to evaluate the effectiveness and potential problems of the multistage hydraulic-fracturing jobs performed in the nine laterals.
To accomplish this goal, the HHF model is run in a numerical-simulation model to evaluate the SRV performance in planar and complex fracture networks using good-quality microseismicity data collected during 75 stages of hydraulic fracturing (out of 145 stages performed in nine laterals). The fracture-network geometry for each hydraulic-fracture (HF) stage is developed on the basis of microseismicity observations and the limits obtained in the fracture-propagation modeling. Post-fracturing production is appraised with rate-transient analysis (RTA) for determining effective permeability under flowing conditions. Results are compared with the HHF simulation and the hydraulic-fracturing design.
The HHF modeling of the SRV leads to a good match of the post-fracturing production history. The HHF simulation indicates interference between stages. The vertical connectivity in the reservoir is larger than the horizontal connectivity. This is interpreted to be the result of the large height achieved by HFs, and the absence of barriers between the formations.
It is concluded that the HHF model is a valuable tool for evaluating hydraulic-fracturing jobs and the SRV in shales of the Horn River Basin in Canada. Because of the generality of the Horn River application, the same approach might have application in other shale gas reservoirs around the world.
Sayers, Colin (Schlumberger) | Lascano, Maria (Schlumberger) | Gofer, Edan (Schlumberger) | Boer, Lennert Den (Schlumberger) | Walz, Milton (Schlumberger) | Hannan, Andrew (Schlumberger) | Dasgupta, Sagnik (Schlumberger) | Goodway, William (Apache Corporation) | Perez, Marco (Apache Corporation) | Purdue, Gregory (Apache Corporation)
Summary Economic production from tight shale formations entails increasing the surface area in contact with the reservoir via hydraulic fracturing. Important to the design of efficient hydraulic fractures is knowledge of the orientation and magnitude of principal stresses and geomechanical rock properties. Using the results of seismic AVA (Amplitude Variation with Angle) inversion calibrated to geomechanical measurements on cores, a 3D MEM (Mechanical Earth Model) is built for an area in the Horn River Basin. The variation in principal stresses over the area is evaluated using the Finite Element Method. Computed stresses are seen to be consistent with variability in production over the area and show stress rotations near faults in agreement with microseismic data.
Hards, Eric Keith (Halliburton Canada Inc.) | Marechal, Francois C (Quicksilver Resources Canada Inc) | Welsh, Jennifer (Quicksilver Resources Canada Inc.) | Verkhovtseva, Natalia (Pinnacle - A Halliburton Service)
This paper presents a case history describing the use of three-dimensional (3D) surface seismic and downhole microseismic data to understand and optimize a fracturing stimulation completion project performed in the Horn River basin (HRB) shale.
The behavior of the hydraulic fractures is interpreted from the data, and a geological theory is then used to further explain the observed data. The theory and observations are then used for completion and stimulation designs on the subsequent well pad.
The target intervals are in the HRB of northeastern British Columbia. They consist of Devonian age clastic sedimentary rocks of the Muskwa and Klua formation that overlie the carbonates of the Keg River formation. Fig. 1 illustrates the HRB geological schematic in the general area.