Date of Award

January 2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Petroleum Engineering

First Advisor

Vamegh Rasouli

Abstract

Hydraulic fracturing treatments are routinely pumped in oil and gas wells worldwide to enhance production and manage the economic recovery of hydrocarbon reserves. The uplift in the production after a fracture stimulation job depends on several parameters, of which optimal coverage of the payzone by the treatment is one of the more important ones. The vertical growth of hydraulic fractures thus is a topic of great interest amongst researchers because of its ability to influence the outcome of a stimulation treatment.

The modeling and prediction of fracture height, especially in layered formations, is a challenging task given the associated complexities often observed when setting up the mathematical model. The models developed for a case where the fracture is confined to the payzone layer surrounded by barriers in a simple 3-layer case, serves as a starting point for developing more complex models that can account for stress and mechanical property changes in layered or laminated reservoir with contrasting properties. In this study, the solution to such complex and rigorous mathematical problems were obtained by developing a simulation model which adopted a semi-analytical approach during the computational process.

Apart from strength and mechanical attributes of the formation rocks, it is also important to account for the fracturing treatment parameters such as the injection rates and fracturing fluid rheology in fracture height estimation process because of the influence they wield. To accurately determine the fracture evolution during the treatment, the newly developed height growth model was extended to enable history matching of the treatment data. To validate this model, it was applied to several field cases worldwide, covering a variety of completions including treatment on shallow coal bed methane wells, low permeability sandstone reservoirs, foamed fluid treatments, offshore frac packs, and high-rate fracturing treatments typically pumped in unconventional reservoirs. The fracture dimensions predicted by the model reasonably matched the field observations and also led to additional model-enhancements.

The findings from the research were published in various journals and shared with audiences worldwide via presentations in SPE conferences. Whilst the prediction of fracture height will continue to attract and engage researchers worldwide, it is hoped that this work will make significant contributions to the existing literature and assist those who wish to continue exploring further in this arena.

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