scholarly journals Assessment of Eagle Ford Shale Oil and Gas Resources

2013 ◽  
Author(s):  
Xinglai Gong ◽  
Yao Tian ◽  
Duane A. McVay ◽  
Walter B. Ayers ◽  
John Lee
Keyword(s):  
Oil And Gas ◽  
Shale Oil ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Oil And Gas Resources

Proppant Distribution in Newly Completed and Re-Fractured Wells - An Eagle Ford Shale Case Study

2021 ◽  
Author(s):  
Justin Allison ◽  
Glyn Roberts ◽  
Brad Hicks Hicks ◽  
Todd Lilly
Keyword(s):  
Oil And Gas ◽  
Treatment Effectiveness ◽  
Design Parameters ◽  
Distribution Analysis ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Video Footage ◽  
Final Consideration ◽  
Fractured Well

Abstract Fracture treatments and stage designs for new wells have evolved considerably over the past decade contributingto significant production growth. For example, in the acreage discussed hererecently used higher intensity fracturing methods provided an ~80% increase in recovery rates compared with legacy wells. Older wells completed originally with less efficient techniques can also benefit from these more up-to-date designs and treatments using re-fracturing methods. These offer the prospect of economically boosting production in appropriately selected wells. While adding in-fill wells has often been favored by Operators as a lowerrisk option the number of wells being re-fractured has grown every year for the last decade. In this case study two adjacent Eagle Ford wells, comprising a newly completed and a re-fractured well, allow both methods to be considered and compared. Completion design and fracture treatment effectiveness are evaluated using the uniformity of proppant distribution at cluster and stage level as the primary measure. Perforation erosion measurements from downhole video footage is used as the main diagnostic. Novel data acquisition methods combined with successful well preparation provided comprehensive and high-quality datasets. The subsequent proppant distribution analysis for the two wells provides the highest confidence results presented to date. Clear, repeatable trends in distribution are observed and these are compared across multiple stage designs for both the newly completed and re-fractured well. Variations in design parameters and how these effects distribution and ultimately recovery are discussed. These include changes to perforation count per cluster, cluster spacing, cluster count per stage, stage length, perforation charge size and treatment rates and volumes. As a final consideration production records for the evaluated wells are also discussed. Historical industry data shows that the number of wells being re-fractured increases relative to the number of newly drilled wells being completed during periods of low oil and gas prices. With the industry again facing harsh economic realities an increasing number of decisions will be made on whether new or refractured wells, or a combination of both, provide the best solution to replace otherwise inevitable production decline. This paper attempts to provide a detailed understanding of how proppant distribution, as a significant factor in production for hydraulically fractured wells, can be evaluated and considered in these decisions.

Effects of maturation on multiscale (nanometer to millimeter) porosity in the Eagle Ford Shale

2015 ◽  
Vol 3 (3) ◽  
pp. SU59-SU70 ◽  
Author(s):  
Lawrence Michael Anovitz ◽  
David Robert Cole ◽  
Julia Meyer Sheets ◽  
Alexander Swift ◽  
Harold William Elston ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Pore Structure ◽  
Oil And Gas ◽  
Total Porosity ◽  
The United States ◽  
Total Surface Area ◽  
Eagle Ford Shale ◽  
Rock Composition ◽  
Eagle Ford ◽  
Gas Targets

Porosity and permeability are key variables that link the thermal-hydrologic, geomechanical, and geochemical behavior in rock systems and are thus important input parameters for transport models. Neutron scattering studies indicate that the scales of pore sizes in rocks extend over many orders of magnitude from nanometer-sized pores with huge amounts of total surface area to large open fracture systems (multiscale porosity). However, despite considerable efforts combining conventional petrophysics, neutron scattering, and electron microscopy, the quantitative nature of this porosity in tight gas shales, especially at smaller scales and over larger rock volumes, remains largely unknown. Nor is it well understood how pore networks are affected by regional variation in rock composition and properties, thermal changes across the oil window (maturity), and, most critically, hydraulic fracturing. To improve this understanding, we have used a combination of small- and ultrasmall-angle neutron scattering (U)SANS with scanning electron microscope (SEM)/backscattered electron imaging to analyze the pore structure of clay- and carbonate-rich samples of the Eagle Ford Shale. This formation is hydrocarbon rich, straddles the oil window, and is one of the most actively drilled oil and gas targets in the United States. Several important trends in the Eagle Ford rock pore structure have been identified using our approach. The (U)SANS results reflected the connected (effective) and unconnected porosity, as well as the volume occupied by organic material. The latter could be separated using total organic carbon data and, at all maturities, constituted a significant fraction of the apparent porosity. At lower maturities, the pore structure was strongly anisotropic. However, this decreased with increasing maturity, eventually disappearing entirely for carbonate-rich samples. In clay- and carbonate-rich samples, a significant reduction in total porosity occurred at (U)SANS scales, much of it during initial increases in maturity. This apparently contradicted SEM observations that showed increases in intraorganic porosity with increasing maturity. Organic-rich shales are, however, a very complex material from the point of view of scattering studies, and a more detailed analysis is needed to better understand these observations.

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