Tiltmeter Hydraulic Fracturing Mapping on a Cluster of Horizontal Wells in a Tight Gas Reservoir

Abstract

This reservoir is a tight gas field and the target sand stone zones are generally staged fracturing treated at depths of roughly 1500 to 2800 meter. Knowing the direction or azimuth of the fracture orientation is important in development of this low permeability reservoir with horizontal wells. The paper presents surface tiltmeter hydraulic fracturing mapping results of 15 stages treatment in two horizontal wells at the same operational period. The two wells are part of a cluster of six horizontal wells located in North of Yulin, Shanxi province. Application of this technology is important in this tight gas field where fracture stimulation is a key method for production enhancement and reservoir development. This was the first deployment of tiltmeter mapping on a cluster of horizontal wells, and several modifications were made for the standard procedures. Using an array of 54 Surface Tiltmeters, the mapping was performed on all 15 treatments with the average perforation depths of TVD 2540 to 2545m at each horizontal section to determine hydraulic fracture azimuth and fracture length, respectively. For the first horizontal well R-3H, the tiltmeter mapping results show that, the azimuth of fractures is between N53 °E and N71 °E, and the fracture half length for stages fractures is between 112m and 149m. For the second horizontal well R-5H the tiltmeter mapping results show that, the azimuth of fractures is between N67 °E and N76 °E, and the fracture half length for stages fractures is between 107m and 142m. Besides, in the well R-3H from stage 7 to stage 9, the horizontal volume component of fractures, increased from 17% to 34%, as well as in the well R-5H from stage 5 to stage 9, the horizontal volume component of fractures significantly increased to 69% from 20%. Meanwhile, the production of the two wells after the fracturing was the first and second among the cluster of the six horizontal wells, respectively. Thus, by using the synchronous fracturing technology, we believe that it not only improved the complexity of the staged fractures between the two wells but also led to a better production enhancement.

Advancement of Hydraulic Fracture Diagnostics in Unconventional Formations

“…They reported expanded steps in the geomechanical inversion technique for determining the areal extent of the fracture network. Similarly, [81] presented a case study for a tight gas reservoir with a cluster of horizontal wells. They found that the tiltmeter could monitor the fracture network growth during synchronous fracturing across multiple wells.…”

Joint estimation of tiltmeter drift and volume variation during reservoir monitoring

“…In particular, Warpinski (2014) described the current and future uses that tiltmeters network can provide when used in unconventional operating conditions. This includes: 1) mapping fracture's network (Wright et al, 1998;Wright et al, 1997;Zhou et al, 2015), 2) orthogonal and horizontal fractures identification, 3) refracturation processes and 4) fracture's network evolution during fracking processes. Because the ground deformation induced by a single frack is so small (tens of nanometers, Astakhov et al, 2012), only tiltmeters and strainmeters can measure it.…”

Tiltmeter data inversion to characterize a strain tensor source at depth: application to reservoir monitoring

“…Dvorak & Dzurizin, 1997;Masterlark, 2007). Models of magma plumbing systems often include a magma reservoir (pressure source), a conduit (cylinder or ellipsoidal sources) or a dike (planar dislocation), which may or may not reach the surface (Bato et al, 2017;Bonaccorso et al, 2008;Montgomery-Brown et al, 2010;Palano et al, 2008;Segall, 2013), while models of stimulated reservoir volume in hydraulic-fracture treatment consider the superposition of several nearby fractures assimilated to planar dislocations (Astakhov et al, 2012;Warpinski, 2014;Zhou et al, 2015).…”

“…For example, Kamo and Ishihara (1989) and Nishi et al (2007) detected deformation of the order of a nanorad in volcano monitoring, with a maximum precursory tilt change of 10-200 nrad for periods ranging from 10 minutes to 7 hours prior to eruptions. Hydraulic fracturing of low permeable reservoirs (Astakhov et al, 2012;Castillo et al, 1997;Zhou et al, 2015), phreatic eruption (Honda et al, 2018), long term injection of water into borehole (Jahr et al, 2006(Jahr et al, , 2008 or changes in pump rates in the vicinity of fluid-producing wells (Chen et al, 2010) produce small deformation signals detectable by tiltmeters. In addition to the source signal, tilt signal is altered by other strain sources due to tides, hydraulic loading, temperature effect or pressure gradient.…”