Date of Award

May 2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Energy Engineering

First Advisor

Olusegun Stanley D. Tomomewo

Second Advisor

Siamak D. Mishani

Abstract

Unconventional reservoirs across North America have become major sources of oil, gas, and increasingly geothermal energy. Much of this growth is now occurring during a densification phase, where operators add wells to existing pads as surface space becomes limited. Mature plays are increasingly covered by pads, roads, and flowlines, while millions of idle or abandoned wellbores represent a growing climate liability, with methane emissions largely driven by unplugged wells. At the same time, many reservoirs remain incompletely drained, and parent–child well interference reduces incremental recovery. Recent drilling performance also shows that extending laterals to 2 miles can approach the cost and time of drilling 1 mile, improving recovery per surface location.This dissertation evaluates whether advanced multilateral well designs, fishbone wells and U-shaped (horseshoe) wells, can achieve equal or higher expected ultimate recovery (EUR) and project net present value (NPV) than conventional horizontal wells, while reducing surface footprint normalized by recovered energy and lowering energy intensity per unit recovered. A secondary objective is to propose development strategies to reduce the number of wells required to meet a recovery target by developing predictive tools and supporting decisions on geothermal repurposing. The research examines how fishbone and U-shaped wells improve reservoir contact; develops and applies analytical, empirical, and data-driven models to optimize fishbone designs based on branch number, length, angle, spacing, and reservoir anisotropy; develops a dedicated computational tool to evaluate fishbone well performance and perform rapid sensitivity analysis of key geometric design parameters, assesses fishbone wells for enhanced geothermal systems and quantifies heat-extraction gains; evaluates the techno-economic and environmental performance of U-shaped wells relative to two separate horizontals; and establishes spacing and design guidelines using coupled hydraulic-fracture and reservoir simulations across multiple basins. Results show that optimized fishbone configurations improve productivity and can increase geothermal heat extraction by about 30% compared with standard horizontals, with diminishing returns beyond four branches. Life-cycle analysis indicates that U-shaped wells reduce cost per lateral foot, lower water use by 15–20% and cut greenhouse-gas emissions by about 30% by eliminating a vertical section and consolidating surface infrastructure. Coupled simulations across the Williston, Permian, and Anadarko basins further show that U-shaped wells can deliver higher cumulative oil recovery and higher net present value than two-well configurations.

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