Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1904. / The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed December 28, 2009)

Includes bibliographical references (p. 193-206).

The objective of this work was to evaluate chemical interactions in phase behavior experiments that make surfactant-polymer formulations with alkali complex to design. This experimental study of sodium carbonate shows improvement of microemulsion phase behavior with many crude oils in addition to its classical use to produce soap in-situ and raise pH to reduce potential for surfactant adsorption. Soap is generally not sufficient by itself for chemical flooding because it has low tolerance to calcium ions and low optimal salinity. The blending of synthetic surfactant with sodium carbonate is needed to increase the optimum salinity, increase the tolerance to calcium, and reduce the sensitivity to changes in salinity by broadening the active salinity window. Sodium carbonate can also be added to the surfactant formulation to adjust electrolyte concentration for optimal salinity. Evidence suggests that additional consideration should be given to sodium carbonate in enhanced oil recovery applications because of benefits that extend beyond the traditional application. The research presented in this work discusses experiments that were conducted for the purpose of studying the benefits of sodium carbonate on surfactant phase behavior. After phase behavior screening, the formulations were tested to demonstrate their performance in porous media. Core floods were conducted to test the potential use of chemical flooding for a field application with several low acid crude oils. Two of the core flood experiments with Berea sandstone reduced the residual oil below 1% with chemical injection. An acceptable pressure gradient was maintained and good sweep was obtained using an AMPS polymer at high temperature. Polymer was needed to make the slug and drive sufficiently viscous to recover the mobilized oil and reduce surfactant retention through good sweep efficiency. The experiments reported in this research have contributed to an ongoing effort to design a suitable alkali-surfactant-polymer chemical formulation for the application in a high permeability, high temperature (85 ºC) sandstone reservoir located in Indonesia. / text

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The hydrolysis of urea by the widely distributed enzyme urease is special in that it is one of the few biologically occurring reactions that can generate carbonate ions without an associated production of protons. When this hydrolysis occurs in a calcium-rich environment, calcite (calcium carbonate) precipitates from solution forming a solid-crystalline material. The binding strength of the precipitated crystals is highly dependent on the rate of carbonate formation and under suitable conditions it is possible to control the reaction to generate hard binding calcite cement (or Biocement). The objective of this thesis was to develop an industrially suitable cost-effective microbial process for the production of urease active cells and investigate the potential for urease active cells to act as a catalyst for the production of Biocement. The biocementation capability of two suitable strains was compared. Sporosarcina pasteurii (formally Bacillus pasteurii) produced significantly higher levels of urease activity compared to Proteus vulgaris, however the level of urease activity was variable with respect to biomass suggesting that the enzyme was not constitutive as indicated by the literature, but subject to regulation. The environmental and physiological conditions for maximum urease activity in S. pasteurii were investigated and it was found that the potential urease capacity of the organism was very high (29 mM urea.min-1.OD-1) and sufficient for biocementation without additional processing (e.g. concentration, cell lysis). The regulation mechanism for S. pasteurii urease was not fully elucidated in this study, however it was shown that low specific urease activity was not due to depletion of urea nor due to the high concentrations of the main reaction product, ammonium. pH conditions were shown to have a regulatory effect on urease but it was evident that another co-regulating mechanism existed. Despite not fully exploiting the urease capability of S. pasteurii, sufficient urease activity to allow direct application of the enzyme without additional processing could still be achieved and the organism was considered suitable for biocementation. Urease was the most expensive component of the cementation process and cost-efficient production was desired, thus an economic growth procedure was developed for large-scale cultivation of S. pasteurii. The organism is a moderate alkaliphile (growth optimum pH 9.25) and it was shown that sufficient activity for biocementation could be cultivated in non-sterile conditions with a minimum of upstream and downstream processing. The cultivation medium was economised and expensive components were replace with a food-grade protein source and acetate, which lowered production costs by 95%. A high level of urease activity (21 mM urea hydrolysed.min-1) was produced in the new medium at a low cost ($0.20 (AUD) per L). The performance of urease in whole S. pasteurii cells was evaluated under biocementation conditions (i.e. presence of high concentrations of urea, Ca2+, NH4 +/NH3, NO3 - and Cl- ions). It was established that the rate of urea hydrolysis was not constant during cementation, but largely controlled by the external concentrations of urea and calcium, which constantly changed during cementation due to precipitation of solid calcium carbonate from the system. A simple model was generated that predicted the change in urea hydrolysis rate over the course of cementation. It was shown that whole cell S. pasteurii urease was tolerant to concentrations of up to 3 M urea and 2 M calcium, and the rate of urea hydrolysis was unaffected up to by 3 M ammonium. This allowed the controlled precipitation of up to 1.5 M CaCO3 within one treatment, and indicated that the enzyme was very stable inspite of extreme chemical conditions. A cost-efficient cementation procedure for the production of high cementation strength was developed. Several biocementation trials were conducted into order to optimise the imparted cementation strength by determining the effect of urea hydrolysis rate on the development of strength. It was shown that high cementation strength was produced at low urea hydrolysis rates and that the development of cementation strength was not linear over the course of the reaction but mostly occurred in the first few hours of the reaction. In addition, the whole cell bacterial enzyme had capacity to be immobilised in the cementation material and re-used to subsequent applications, offering a significant cost-saving to the process. An industry-sponsored trial was undertaken to investigate the effectiveness of Biocement for increasing in-situ strength and stiffness of two different sandy soils; (a) Koolschijn sand and (b) 90% Koolschijn sand mixed with 10% peat (Holland Veen). After biocementation treatment, Koolschijn sand indicated a shear strength of 1.8 MPa and a stiffness of 250 MPa, which represents an 8-fold and 3-fold respective improvement in strength compared to unconsolidated sand. Significantly lower strength improvements were observed in sand mixed with peat. In combination, trials of producing bacteria under economically acceptable conditions and cementation trials support the possibility of on-site production and in-situ application of large field applications.

Abstract of Thesis (Ph. D.)--University of Michigan, 1936. / Cover title. By Alfred W. Fleer and Alfred H. White. "Reprinted from Industrial and engineering chemistry, vol. 28, no. 11 ... November, 1936." "Literature cited": p. 1309.

Thesis (M.S.)--Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.