Semester

Fall

Date of Graduation

2021

Document Type

Problem/Project Report

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Petroleum and Natural Gas Engineering

Committee Chair

Kashy Aminian

Committee Member

Samuel Ameri

Committee Member

Mehrdad Zamirian

Abstract

Unconventional oil and natural gas play a key role in our nation's future. The U.S. has vast reserves of such resources that are commercially viable as a result of advances in horizontal drilling and hydraulic fracturing technology. These technologies enable greater access to oil and natural gas in shale formations. Responsible development of America's shale gas resources offers important economic, energy security, and environmental benefits. Hydraulic fracturing and horizontal drilling apply the latest technologies and make it commercially viable to recover shale gas and oil.

In order to estimate the original gas-in-place, predict the production rates, and optimize the hydraulic fracturing treatments, reliable values of the shale key petrophysical properties including permeability, porosity, and adsorption characteristics are necessary. The quantification of the shale petrophysical properties however is challenging due to complex nature of the shale. Shale is an organic-rich, naturally fractured formation with ultra-low matrix permeability. The gas is stored in the limited pore space of the shale matrix and may be adsorbed on the organic material. It is not practical to measure the permeability of the shale samples by the conventional laboratory steady-state technique due to extremely low flow rates and the length time required for establishing steady-state conditions. Consequently, different unsteady-state laboratory techniques have been introduced for measuring the permeability of the rock samples from extremely low permeability formations. The most common techniques include GRI, pressure pulse decay, and high-pressure mercury injection. However, the measured permeability values by these techniques often suffer from large margin of uncertainty and non-uniqueness.

In this study the data was obtained from two different shale samples by using the Precision Petrophysical Analysis Laboratory (PPAL). Which utilizes highly accurate pressure and pressure-differential transducers, and it is capable of measuring the permeability in a nano-Darcy range under steady-state conditions. The entire system is enclosed in a clear Lexan container to assure temperature stability. PPAL allows a measurement to be performed on the core plug under confining pressure up to 10,000 psi and the pore pressure up to 1,500 psi. this data has been analyzed and the absolute permeability of the two shale samples was calculated, and the adsorption and desorption effect on the permeability were evaluated using Helium and Nitrogen, finally the impact of pore pressure and net stress on permeability and porosity using Nitrogen were also evaluated. The pore pressure and stress were found to have a significant impact on the measured permeability values. Furthermore, the permeability exhibited hysteresis with increasing and decreasing stress values, the porosity measurements using Nitrogen were not significantly impacted by the stress. Finally, a comparison was performed between the two samples.

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