Browsing by Subject "Diversion"
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Item A Modeling and Experimental Study of Foam in Acid Diversion and Enhanced Oil Recovery(1996-12) Zeilinger, Sabine; Rosen, William R.Foam is used in stimulation treatments and enhanced oil recovery to aid diversion and to improve sweep efficiencies. When they are used as diverting agents during matrix-acidizing treatments, they direct acid flow to low permeability or oil-saturated zones. However, foam mechanisms in rock are complex and not well understood. Foam mobility is controlled by foam texture, which itself is a complex function of many variables. Capillary pressure and the relation between the pore-size distribution of the rock and the texture of the foam, especially, play important roles in foam behavior. This work explores the mechanisms of foam diversion in two ways. The first is mathematical modeling. A theoretical model of foam in rock can be derived from first principles, using a material balance on each component and a population balance on the foam bubbles. However, this method involves the v description of processes that are not well understood. Our investigation focuses on a simpler approach, which was introduced in an earlier work and that describes the dominant mechanism of foams in a rock, applying fractional-flow methods under the assumption of a limiting capillary pressure. We show that the predictions of foam flow using this model are comparable to the other approach, in spite of its simplicity. A second focus of this work is an experimental investigation of the bubble-size distribution in foam. Foam-acid treatments in the field and experimental work published in the literature suggest that foam texture depends on parameters such as the permeability and the pore-size distribution of the porous medium, which reconfigures foam texture. We have built an apparatus that measures both bubble-size distribution as foam exits the medium and the pressure drop caused by the foam in a variety of sandpacks and rock samples.Item On the use of traffic assignment and microsimulation to predict work zone effects(2022-05-06) Smith, Harry Vincent, II; Machemehl, Randy B.The field of transportation modeling exists at a crossroads. Practice lags behind advancements in theory, software, and computer power. During this transitional phase, it becomes difficult to understand which estimations are reliable. Several popular programs work toward similar purposes, but inputs and outputs from one program might not translate to another. This thesis analyzes the cross-compatibility of static traffic assignment and microsimulation for the San Antonio, Texas area. The methodology uses two models already built and in use for the area: one in TransCAD for static traffic assignment and another in VISSIM for microsimulation. In Chapter 2, the reader is presented an overview of the literature on several topics. First, the basics of work zone demand management and traffic control plans are covered. Then, this section introduces the differences between static and dynamic traffic assignment. The discussion also includes reasons why advancements have not been universally implemented yet. Next, the text of Chapter 3 and 4 explains the methodology and results from traffic assignment and microsimulation. Challenges and successes of the entire process are thoroughly explored. A conclusion in Chapter 5 assesses the feasibility of combining the two methods to obtain useful results of user delay and traffic volume for planners.