Assessment of Eagle Ford Shale Oil and Gas Resources

, and estimated ultimate recovery (EUR) was calculated using two empirical production decline curve models, the hyperbolic and the stretched exponential function. Individual well productivity, which can be described by IP level, production decline curvature and well lifetime, varies significantly. The average monthly IP was found to be around 500 bbl/day, which yields an EUR in the range of 150-290 kbbl depending on used curve, assumed well lifetime or production cutoff level. More detailed analyses on EUR can be made once longer time series are available. For more realistic modeling of multiple wells a probabilistic approach might be favorable to account for variety in well productivity. For less detailed modeling, for example conceptual regional bottom-up production modeling, the hyperbolic function with deterministic parameters might be preferred because of ease of use, for example with the average parameter values IP = 500 bbl/day, D = 0.3 and b = 1 resulting in an EUR of 250 kbbl with a 30-year well lifetime, however, with the recognition that this extrapolation is uncertain.

show abstract

“…Another possible factor could be the API gravity of the oil that differs from county to county. This has been discussed by Gong (2013).…”

Section: Discussionmentioning

confidence: 94%

Production Decline Curves of Tight Oil Wells in Eagle Ford Shale

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Oil gravity and gas specific gravity are input parameters to reservoir models and are used in reserves estimations (McCain, 1990;Gong et al 2013, Yu et al 2013. In earlier stages of this project, multiple single-well models were built for history match and production forecast (Gong et al 2013).…”

Section: Oil Gravity and Gas Specific Gravitymentioning

confidence: 99%

“…In earlier stages of this project, multiple single-well models were built for history match and production forecast (Gong et al 2013). However, these parameters may be mapped regionally, to better understand reservoir fluids and well production.…”

Section: Oil Gravity and Gas Specific Gravitymentioning

confidence: 99%

“…Eagle Ford Shale fluid types evolve with increasing depth from black oil to volatile oil, gas condensate, and finally, to dry gas, along the Edwards and Sligo Shelf Margins (Tian et al 2012). Peak production of oil wells is greatest in Karnes, DeWitt, and southern Gonzales Counties, where production exceeds 16,000 bbl./month/well ( Fig.6) (Tian et al 2013). The most productive gas wells are located south of the Stuart City Shelf Margin in LaSalle and Webb Counties, where production commonly exceeds 80 MMcf/month/well ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The most productive gas wells are located south of the Stuart City Shelf Margin in LaSalle and Webb Counties, where production commonly exceeds 80 MMcf/month/well ( Fig. 7) (Tian et al 2013). …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Regional Impacts of Lithologic Cyclicity and Reservoir and Fluid Properties on Eagle Ford Shale Well Performance

Tian

Ayers

McCain

2014

SPE Unconventional Resources Conference

View full text Add to dashboard Cite

Since 2008, the Eagle Ford Shale has been one of the most active U.S. oil and gas plays. Regional variations of the frequency (cyclicity) and thickness of organic-rich marl and limestone interbeds influence well completion design, and these variations may be related to well production performance. To better understand the impacts of lithologic cyclicity and reservoir and fluid properties on well performance, we conducted an integrated, regional study using well logs, production data, and PVT reports.Regionally, the Eagle Ford Shale is composed of 3 units. The Lower Eagle Ford consists of cyclic, interbedded organic-rich marl and limestone. To analyze lithologic cyclicity of the Lower Eagle Ford Shale in South Texas, We evaluated gamma ray logs from more than 500 vertical wells. A Matlab script was developed to count the numbers of organic-rich marl and limestone interbeds. Average bed thickness was calculated at each well and was mapped regionally. The numbers of both limestone and organic-rich marl interbeds increase from less than 2 in the northwest to more than 20 on the southeast. Lithologic cyclicity is greatest in La Salle and Karnes Counties, which are the most productive gas and oil regions, respectively.Eagle Ford Shale reservoir and fluid properties from PVT reports were mapped to further evaluate regional variations of fluid types and well performance. Reservoir pressure, pressure gradient, oil gravity, and gas specific gravity were mapped. Reservoir pressure and pressure gradient are greatest on the northeast. Oil gravity and gas specific gravity maps suggest increasing thermal maturity from northwest to southeast, with increasing depth.Well production rates are strongly influenced by lithologic cyclicity, pressure, and fluid properties. Understanding these relations in the lower Eagle Ford Shale should assist with optimizing completion design and stimulation strategies. The results of this study provide a better understanding of Eagle Ford Shale reservoir characteristic and well performance, and the study approach may be used to assess productivity of other shale plays.

show abstract