Abstract
Microseismic data acquired using a near-surface array in four horizontal wells in the Haynesville shale in Shelby and San Augustine counties, Texas, were analyzed and integrated with geoscience, petrophysics, completions, and flow-back performance data. Horizontal sections of the wells are ~5,000 feet long, and stimulated with twelve stages. Analyses of microseismic events from the first two wells to understand fracture containment, led to drilling the fourth as a transverse across the target zone. A production log was also run in the same well to identify zones in the Haynesville that produced the highest rate of gas. Fewer microseismic events were recorded during stimulations of the northward wells, and resulting fractures were more elongated than the southward wells. Fracture half-lengths based on all located microseismic events from the four wells range between ~400 feet and ~700 feet. The derived fracture orientations are consistent with the regional SHmax and confirm our choice of well azimuths. Some prominent fractures align with those inferred from 3-D seismic based coherency attribute, indicating that pre-existing fractures were activated. Correlations of microseismic event locations with gamma ray logs along the laterals revealed that fractures initiated better when the log values are <110 API, an observation consistent with Lithology-based brittleness index. The completions strategy included pumping resin coated sand in one well, combining that with white sand in others, and stimulating the shortest lateral with the same proppant volume and stages as others. Flow-back performance of the shortest lateral was strong enough to suggest the potential for reserve improvement by shortening stage length. The interpreted production log shows that stages near the heel are most productive compared to the first three stages near the toe, leading to an estimate of the effective stimulated rock volume. Summarily, the study provides multidisciplinary insights into future horizontal designs in the area.
