Semester of Graduation

Summer 2021

Degree

Master of Science in Petroleum Engineering (MSPE)

Department

Petroleum Engineering

Document Type

Thesis

Abstract

Enhanced oil recovery (EOR) is essential in shale/tight formations because primary recovery typically produces less than 10% of the original hydrocarbon in-place (OHIP). This work presents a novel “slot-drill” EOR technology, which involves injecting gas through a horizontal fracture that is cut into the formation near the top of the reservoir (using a tensioned abrasive cutting cable mounted to the drillstring) and producing oil from a second slot-drilled horizontal fracture near the bottom of the reservoir.

The dusty-gas diffusion model was implemented in a compositional simulator to account for the diffusion mechanism expected during the injection of gases in this EOR process. The simulation results indicate that the simulated contribution of molecular diffusion to production increases as the mesh gets finer and matrix permeability decreases. Additionally, a robust 3D projection-based embedded discrete fracture model is used to model the natural fractures in these slot-drilled unconventional oil reservoirs accurately and efficiently. Connectivity and uncertainty analyses are performed to determine the percolation threshold, where natural fractures influence hydrocarbon production appreciably. The results of this work indicate that the proposed technology can yield over a three-fold increase in oil recovery relative to the cyclic gas EOR (CGEOR) method. This simulated recovery is high regardless of the presence of natural fractures or the type of gas/solvent injected (such as CH4, N2, CO2, and flue gas). The simulation results also indicate that the continuous gas injection, higher relative oil permeability, and the role of gravity-drainage are the main reasons why the oil recovery from the SDEOR is three times that from the CGEOR method.

In conclusion, this thesis is the first to introduce the SDEOR technology and demonstrate its potential to improve recovery from challenging unconventional reservoirs (such as the Bakken shale), which has not been successfully enhanced using the conventional cyclic gas EOR. The three-fold to nine-fold improved recovery from the SDEOR, coupled with its applicability regardless of the stress state or rock brittleness, could change how unconventional reservoirs are completed and produced in the future.

Committee Chair

Olorode, Olufemi

Available for download on Sunday, July 10, 2022

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