The January issue of American Oil & Gas Reporter included a contributed article by Duane Dopkin, and Jean-Claude Dulac. The headline was “Integrated Software Helps Improve EUR.” Here’s a summary:
Emerging technical software solutions are driving a new set of geoscientific and engineering workflows that give operators the critical insights needed to improve estimated ultimate recovery in tight oil reservoirs. Tight oil reservoirs have assumed a noticeable and influential position in the world’s crude oil supply, with production from new oil field “giants,” such as the Eagle Ford and Bakken/Three Forks, pushing U.S. crude oil supply to more than 10 percent of the world’s total, according to the U.S. Energy Information Administration.
Caption: Full-Azimuth, 5-D Common Reflection Point Image Prestack Gather
As production from these fields continues to grow, geoscientists and engineers remain challenged as to how to boost estimated ultimate recovery from these tight reservoirs. While the overwhelming successes of horizontal drilling and hydraulic fracturing operations have resulted in a new brand for these assets–“technology reservoirs”–it is somewhat ironic that the industry’s poor understanding of reservoir performance can be attributed to the underutilization of new technologies that better explain the heterogeneities that characterize low-permeability reservoirs.
This underutilization is not driven by a lack of understanding or desire, but rather by the fierce pace of drilling, which compromises our ability to fully understand reservoir conditions and performance. This practice, however, is changing by economic necessity as operators are allocating more time to model and analyze local reservoir conditions and properties (stress, rock composition/mineralogy, total organic carbon, etc.) in search of correlations and analogs that can be used to better predict reservoir performance outcomes in new acreage areas. Additionally, technology providers have been challenged to improve the time to a quality reservoir model that captures the totality of exploration and completions technology and data.
The industry’s focus on optimizing the development of low-permeability oil plays is increasing the relevance of reservoir geophysics. Specifically, tight oil reservoirs have accelerated the development of seismic imaging and reservoir characterization methods that greatly enhance geoscientists’ understanding of the geomechanical properties of the subsurface. Today, seismic imaging procedures are able to use surface-recorded seismic data to recover images of fracture intensity, fracture density, fracture orientations, stresses, brittleness, facies, and even estimates of total organic carbon. These images can help geoscientists and engineers define permeability and low-stress zones, identify preferred drilling directions, and optimize well spacing.
New 5-D Procedure
To improve on traditional processes, a new procedure has been developed for the seismic imaging and characterization of fractures. This procedure performs a five-dimensional decomposition and imaging of surface-recorded seismic data in situ, in depth, and over all azimuths and angles.
The petrophysical analysis of tight oil formations plays a fundamental role in understanding the mechanical behavior of tight oil formations and their total organic carbon.
Microseismic data have proven to be an effective tool in estimating the volumetric extent of formations impacted by hydraulic fracturing, understanding the stimulation efficiencies along horizontal wells, optimizing well spacing, and mitigating hazards. This information is fundamental in assessing reservoir heterogeneity and planning future wells.
Pulling together all of the field data and diversity of the processed information and deliverables is not a trivial task. Interpretation systems need to be able to incorporate multiple seismic surveys and extend project areas as new acreage and data are acquired. They also must incorporate readily accessible and high-resolution visualization methods to co-render different attributes and maps.
Horizontal drilling and fracturing operations have transformed tight oil plays from interesting and potential hydrocarbon sources to real and significant contributors to world oil supply. The industry is at a pivot point where a more thorough understanding of the structural and compositional formation fabric can boost EURs from these tight reservoirs. Emerging petrotechnical software solutions are driving a new set of workflows for the geoscientists and engineers tasked with keeping these oil fields at the forefront of the global energy landscape.