Unconventional Resources

Kamy Sepehrnoori (kamys@mail.utexas.edu) is the Program Manager of the Unconventional Resources research program at CPGE.

The Unconventional Resources program includes areas such as rock imaging, well monitoring, fluid production, water management, well construction, fracture fluid additives, gas hydrates and rock microstructure.

Questions and Problems

  • Nanoscale/microscale: How to characterize the rock microstructure and the filaments of organic matter, so that the fluid hydrocarbon storage and rock permeability of mudrocks are correctly captured?

     
  • Microscale/mesoscale: What is the connectivity of flow channels of any kind on the scale of centimeters/meters?

     
  • Affecting rock microstructure: How to locally manipulate state of stress to increase the rock permeability? How to cause local stress unloading, break rock bonds, and generate/link microcracks and/or microfractures?

     
  • Well construction: Given the improved knowledge of rock structure at micro and mesoscale, how can one connect a block of rock to a well, and how can one influence the state of stress in this block from a well?

     
  • Drilling and completing wells in mudrock systems: What are the best fluids to use, and what are their benefits and shortcomings?

     
  • Well monitoring: How does one monitor in the dynamic state of rock around a wellbore with evolving the well state and controlling it in mind?

     
  • Development planning, economics, and risk management: How best to handle uncertainty in all stages of the decision-making process so as to manage risks and optimize production rate and ultimate recovery from unconventional resources?

     
  • Rock imaging: How can one image the effects of changes of rock state on hydrocarbon production?

     
  • Water management: How to design improved, reliable, and energy-conserving reverse osmosis and membrane processes of produced water purification?

     
  • The mechanisms controlling the fracture propagation rates of multiple fracture tips in complex hydraulic fracturing need to be identified. Hydraulic fracturing processes lie in the poorly studied area between critical/dynamic fracture growth and subcritical growth, and as such are probably likely to be highly sensitive to changing chemical and geomechanical in situ environments.

     
  • As most unconventional reservoirs contain an abundance of natural discontinuities, fundamental experimental and numerical work are required to enhance the predictability of hydraulic fracture propagation. No currently available commercial model is capable of the realistic simulation of multistranded, non-planar fracture propagation.

     
  • Fluid production must be optimized over the life of the well, especially concerning the efficient lift liquids from highly deviated wells through appropriate pump choice and placement.

 

Research Projects

Principal Investigator: Huge Daigle (in collaboration with Nicholas W. Hayman (UTIG), Kyle Spikes, UT Department of Geological Sciences, Julia Gale, Peter Eichhubl, Kitty L. Milliken (BEG))

David DiCarlo and Quoc P. Nguyen

One of the keys for enhancing recovery from gas shales is to maximize the flowback of the fracturing fluid.

We propose to develop a surfactant as an additive that can be applied to either water based or CO2 foam fracturing fluids. This additive will act to lower the interfacial tension (IFT) between brine and the gas in place. This will decrease the capillary forces binding the water to the shale, and will increase the water flowback for enhanced gas and condensate recovery.

Principal Investigator: Steven L. Bryant (in collaboration with Masa Prodanovic, Peter Eichhubl (BEG) and Peter Flemings (BEG))

Mechanisms of Porosity Reduction

Several unique characteristics of these rocks are the consequence of post depositional diagenetic processes including mechanical compaction, quartz and other mineral cementation, and mineral dissolution. These processes lead to permanent alteration of the initial pore structure causing an increase in the number of isolated and disconnected pores and thus in the tortuosity.

Nicolas Espinoza

Advanced completion methods seek to maximize the stimulated reservoir volume as a result of hydraulic fracturing. Shale acidization has been proposed as one method to improve drainage efficiency.

Nicolas Espinoza

Tight rocks host hydrocarbons in different pore habits, including fluid in bulk conditions, in adsorbed state, as a solute in fluid phases, or a mixture of these three. Organic rocks show a high potential for adsorption. In fact, sometimes more fluid can be stored in adsorbed state than in bulk conditions in these types of rocks.

Principal Investigator: Steven L. Bryant (in collaboration with Ruben Juanes, MIT)

In the long term, methane hydrates are an interesting potential resource. In the Arctic, hydrate accumulations with large saturations (more than 70% of pore space) are well documented, making the energy density (MCF per unit volume of rock) an order of magnitude greater than in tight gas sandstone or shale gas reservoirs. Similar accumulations exist in sands below sufficiently deep water. We have developed a sedimentological model of a process by which such accumulations may have formed below the permafrost in Arctic regions. Crucially, the model explains why good reservoir sands are often only partially filled with large saturations of hydrate, and why layers containing mostly water often occur between layers of containing hydrate.

Hugh Daigle in collaboration with Kishore Mohanty, Steven Bryant, Alberto Malinverno (Lamont-Doherty Earth Observatory, Columbia University) and Ann Cook (School of Earth Sciences, Ohio State University), with PhD Student Michael Nole (UT PGE)

Quoc P. Nguyen

Vapor oil gravity drainage (VOGD) is an important mechanism of viscous oil recovery in naturally fractured reservoirs where the displacement of matrix oil is challenging.

Masa Prodanovic and Steven Bryant

 The geometry of intergranular pore space in tight gas sandstones (at the porosities less than 10%) differs from conventional reservoir sandstones in some fundamental aspects: the fluid pathways are significantly narrower so that pore body/pore throat aspect ratios are larger, and some percentage of the fluid pathways are closed and disconnect the pore space.

Graduate student: Brian Lee
Principal Investigator: Larry Lake

The goal of the project is to develop a probabilistic graphical model that, when given some properties of the reservoir, produces a predicted value of recovery factor. The fundamental mechanics behind this process is described as Bayes’ updating applied to a chain of variables, each with its own probability distribution.

Nicolas Espinoza

Source rocks can host vast amounts of oil and gas. However, these hydrocarbons are usually highly dispersed in complex and heterogenous formations. Dispersedness and heterogeneity require significant formation evaluation pre-studies and reservoir stimulation actions to maximize the net energy return and the recovery ratio.

Tadeusz Patzek

Introduction: By 2011, the unconventional resource plays in the U.S. have become a 300 billion dollar bet about the future of energy supply for our great country.

Tadeusz Patzek

Introduction: Rock damage is the process of breakage of grain bonds and the initiation and growth of discontinuous microcracks that may coalesce into a fracture.

There are a great number of damage models, plasticity models and methods for modeling rock fractures. The available models of fracture growth do not account for microstructural effects in damage accumulation. We are looking at fracture and change of rock properties from microstructural level and using methods of homogenization of heterogeneous materials, we go from local damage model to non-local damage.