EORI Library

The authors use multivariate statistics to highlight best practices in the drilling of Codell and Niobrara reservoirs of the northern Denver-Julesburg (DJ) Basin in southeastern Wyoming. The conclusions in this paper differ from a 2017 report by the Wyoming State Geological Survey on the same topic and illustrate why simple crossplots are not sufficient to properly analyze plays where a number of variables must be addressed and weighed simultaneously.

For the Codell, this study reveals that the attributes of Proppant Volume, Horizontal Length, Gas-Oil Ratio (GOR), and Treatment Rate have the greatest influence on 6-, 12-, and 18-month cumulative oil production. By examining the individual attribute responses, the current best design in the Codell is a lateral length of at least 9,600 feet (ft), a job size of 12 million (MM) lbs, a treatment rate of at least 40 barrels per minute (bpm), and a GOR of 570 standard cubic feet per barrel (scf/bbl). The type curves from decline curve analysis provided predictive monthly production. The best EURs were obtained with the optimized design and yielded better overall economics when entered into the economic model.

For the Niobrara, a 9MM lb job size with a lateral length of 10,000 ft, a GOR of 900 scf/bbl, and a treatment rate between 40 and 45 bpm is optimal. Due to lack of available pricing data and the inability to generate valid type curves of production, an economic analysis could not be conducted for the Niobrara.

The Great Plains Institute (GPI) and the University of Wyoming’s Jeffrey Brown explore the planning of CO₂ transportation networks on a regional scale and ascertains the economic and environmental benefits that can be achieved through economies of scale to meet the US midcentury decarbonization goals.

This paper represents the results of modeling efforts to identifying regional scale CO₂ transport infrastructure that would serve existing facilities and allow participation by new capture projects and facilities in the near future.

Topics covered in this briefing:

• Ongoing Operator & Vendor Support
• WY Energy & Policy Insights
• Wyoming CO2-EOR Potential & Impact
• Impact of Electricity Costs on Oil/Gas Development
• Proposed Benchmarking

After several decades of decline Wyoming’s oil production is now turning higher thanks to higher oil prices, the development of condensates, and investments in tertiary methods such as CO2 Enhanced Oil Recovery (CO2-EOR). The present work brings together two prior pieces of research by integrating the economic impact model of Cook (2013a) with the scoping estimates of Wyoming’s CO2-EOR potential found in Cook (2013b). The hope is that discussing the potential economic contribution of CO2-EOR will help inform industry participants and policy makers for the further development of CO2 infrastructure in the state.

Play Based Exploration, or PBE, is a phrase that is being heard more and more frequently as Explorers return to their geological roots in the increasingly demanding search for exploration opportunities, in particular those which offer the potential to add material hydrocarbon volumes to our portfolio.

The North Cross (Devonian) Unit, currently operated by Occidental Oil and Gas, was discovered in 1944. The field was developed using regular 40 acre spacing and produced under primary recovery until 1964. Subsequently, a partial pressure maintenance program was constituted to inject residue gas in an updip location in the field. Large-scale continuous CO2 injection began in April 1972 and was expanded over time to provide CO 2 support throughout the field. The field has been under continuous CO 2 flood for over four decades. Currently, over 200% hydrocarbon pore volume (HCPV) of CO2 has been injected, and over 60% of the latest estimate of its target original-oil-in-place (OOIP) has been recovered. The field continues to perform well with a gross utilization (MCF CO2 injected/bbl oil recovered) of approximately 30 MCF/BO (20 MCF/BOE). North Cross is an excellent example of a successful mature continuous CO2 flood.

• CO2 Foam Stabilization using nanoparticles
• Numerical simulation of tight fractured gas reservoirs
• Process based models guided by seismic data
• Data-driven flood modeling/ management

• Data Driven Reservoir Management
• Development of a Fully Compositional Model for Timber Creek
• Impact of Primary Strata on Recovery Factors in Aeolian
• Systems
• Wertz Tensleep

This study will seek a methodology to improve (a) accuracy in estimates of oil recovery factors and (b) planning field development including well spacing and arrangement. Further, we will create and apply laboratory measurements to understand movement of petroleum fluids at small scales in order to better evaluate upscaling techniques and verify the underlying assumptions of previous works. The proposed study has the potential to impact reserves estimates and production in Wyoming, because it addresses phenomena that constitute bulk properties of all eolian reservoirs in Wyoming and their remaining reserves along with new fields that may be discovered in eolian system rocks such as the Tensleep, Minnelusa, Leo, and Navajo Sandstones.