J. P. Blangy

Microseismic depletion delineation

ABSTRACTHess Corporation performed an extensive data collection project in 2011 designed to investigate infill well spacing in the Williston Basin. Using combined microseismic and pressure data collected from six observation wells and the original depleted horizontal wellbore, we identified the potential for using microseismic data to monitor the extent of depletion in unconventional reservoirs. We propose broader use of this surveillance process, which we call microseismic depletion delineation. We recommend pumping pressurized fluids into, or in the vicinity of, a well that has been on production while simultaneously monitoring for microseismic events as a means to discover the optimal spacing for development wells. Our measurements revealed that depletion over a two-and-a-half year period puts the reservoir in a critically stressed state. By repressurizing the depleted wellbore to a level below the minimum horizontal stress, we promoted shear events that revealed the location of the connected, permeabl...

Integration of seismic and gravity data — A case study from the western Gulf of Mexico

A 3D gravity model was developed in the western Gulf of Mexico in the East Breaks and Alaminos Canyon protraction areas. This model integrated 3D seismic, gravity, and well data; it was constructed in support of a proprietary seismic reprocessing project and was updated iteratively with seismic. The gravity model was built from seismic horizons of the bathymetry, salt layers, and the acoustic basement; however, the latter was only possible to map in seismic data during the latest iterations. In addition, a deep layer representing the Moho boundary was derived from gravity and constrained by public-domain refraction data. A 3D density distribution was derived from the seismic velocity volume using a modified Gardner equation. The modification comprised imposing a depth dependency on the Gardner coefficient, which is constant in the classic Gardner equation. The modified coefficient was derived from well data in the study area and public-domain velocity-density data sets. The forward-calculated gravity response of the composed density model was then compared with the observed gravity field, and the mismatch was analyzed jointly by a seismic interpreter and a gravity modeler. Adjustments were then made to the gravity model to ensure that the resultant salt model was geologically reasonable and supported by gravity, seismic, and well data sets. The output of the gravity modeling was subsequently applied to the next phase of seismic processing. Overall, this integration resulted in a more robust salt model, which has led to significant improvements in subsalt seismic imaging. The analysis of the regional trend in the observed gravity field suggested that a stretched continental crust underlay our seismic reprocessing area, with an oceanic-continental transition zone located to the southeast of our reprocessing region.

Using digital rocks and simulations of pore-scale multiphysics to characterize a sandstone reservoir

AbstractThe modeling and prediction of transport and elastic properties for sandstones are critical steps in the exploration and appraisal of hydrocarbon reservoirs, particularly in deepwater settings where seismic data are abundant and well costs are high. Reliable multiphysics modeling of reservoir rocks requires robust models that respect the underlying geologic character and microstructure of the geomaterial and honor the measured properties. We have developed a case study that integrates traditional laboratory measurements with computational methods to quantify and relate physical properties of reservoir sandstones. We evaluate the complementary use of digital rock simulations as a practical technology that adds physical insight into the development and calibration of rock-property relationships. We also determine the challenges faced while applying digital rock physics to interpret laboratory data, and the steps taken to overcome those limitations. Combining physical and computational methods, we ac...

Introduction to special section: Microseismic monitoring

The use of microseismic data in unconventional resource exploration has grown tremendously over the past decade. While there is a long history of its use in the mining and geothermal industries, its routine application in exploration has grown alongside the proliferation of tight ‘unconventional

Seismic rock physics in the presence of attribute noise

Classic Amplitude versus Offset (AVO) theory has developed a sound framework for understanding seismic rock physics in a noise-free context. (Foster et al., 2010) However, it has long been understood that noise in the offset domain becomes correlated in the various attribute domains, and can lead to “noise-forming”—the apparent rotation of attribute crossplots. (Cambois, 1998; Hendrickson, 1999; Saleh and de Bruin, 2000) In some domains such as Lambda-rho:Mu-rho reflectivity (LR:MR), noise-forming can actually lead to noisy attributes that are anti-correlated with the expected values (See Figure 1.)