Sandstone acidizing has been carried out with mud acid which combines hydrochloric acid and hydrofluoric acid at various ratios. The application of mud acid in sandstone formations has presented quite a large number of difficulties like corrosion, precipitation of reaction products, matrix deconsolidation, decomposition of clays by HCl, and fast spending of the acids. There has been a recent trend to use chelating agents for stimulation in place of mud acid which are used in oil industry widely for iron control operations. In this study, two chelates, L-glutamic-N, N-diacetic acid (GLDA) and hydroxyethylethylene-diaminetriacetic acid (HEDTA) have been studied as an alternative to mud acid for acidizing. In order to analyze their performance in the application of acidizing, coreflood tests were performed on Berea and Bandera sandstone cores. Another disadvantage of mud acid has been the fast spending at clay mineral surfaces leading to depletion of acid strength, migration of fines, and formation of colloidal silica gel residue. Hence, compatibility of chelates with clay minerals was investigated through the static solubility tests. GLDA and HEDTA were analyzed for their permeability enhancement properties in Berea and Bandera cores. In the coreflood experiments conducted, it was found out that chelating agents can successfully stimulate sandstone formations. The final permeability of the Berea and Bandera cores were enhanced significantly. GLDA performed better than HEDTA in all applications. The substitution of seawater in place of deionized water for mixing purposes also led to an increased conductivity of the core implying GLDA is compatible with seawater. In the static solubility tests, chelates were mixed with HF acid at various concentrations. GLDA fluids kept more amounts of minerals in the solution when compared with HEDTA fluids. Sodium-based chelates when mixed with HF acid showed inhibited performance due to the formation of sodium fluorosilicates precipitates which are insoluble damage creating compounds. The application of ammonium-based chelate with HF acid was able to bring a large amount of aluminosilciates into the solution. The study recommends the use of ammonium-based GLDA in acidizing operations involving HF acid and sodium-based GLDA in the absence of the acid.

Vanadium is commonly used as an agent to make tools rust-resistant. As a transition metal, it can be used as a catalyst due to its ability to change oxidation states. VO(HEDTA)-1, a complex of the vanadyl ion, VO2+ and HEDTA (N-(2-Hydroxyethyl)ethylenediamine-N,N’,N’-triacetic acid) was readily formed. This complex containing vanadium in the +4 oxidation state was reacted with hydrogen peroxide to form a vanadate complex. This vanadate complex was formed as a first step in simulating the vanadate(V)-dependent haloperoxidases in marine algae, a yet uncharacterized reaction. Electron absorption spectroscopy (UV-Vis) was used to observe the oxidation of V(IV) in the complex to V(V) through the color change of the complex from blue to yellow. This color change was observed through the formation of a peak at 450nm. By changing the initial concentrations of VO(HEDTA)-1, hydrogen peroxide, and hydronium ion, the change in absorbance at 450nm during the first minutes of the reaction was correlated with time to determine the initial rates for each reactant. Using this method, a rate equation for the reaction was determined. The rate of reaction was determined to be first order with respected to VO(HEDTA)-1 and H2O2, and 1/2 order with respect to H+. This half-order indicates that the hydronium ion is engaged in a reversible reaction. The involvement of hydroxyl radicals produced by the reaction, as shown by the effect of free radical scavengers to inhibit the reaction was also studied.

The novel compound, [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4] was synthesized. Crystal structures of [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4]·2NCC6H5 and Ba1.5[Fe(C10H13N2O7)][Co(CN)6]·9H2O were determined employing a Rigaku Mercury375R/M CCD (XtaLAB mini) diffractometer with graphite monochromated Mo-Kα radiation. For [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4]·2NCC6H5, the space group was P-421c(#114) with unit cell dimensions: a =11.0169(14)Å, c =21.499(3)Å, V = 2609.4(6)Å3. Each rhodium had approximately octahedral coordination and was bound to another rhodium atom, two nitrogens (trans to each other), two oxygens (trans to each other), and one benzonitrile nitrogen (trans to rhodium). For Ba1.5[Fe(C10H13N2O7)][Co(CN)6]·9H2O the space group was: P-1(#2) with unit cell dimensions: a=13.634Å, b=13.768Å, c=17.254Å and α=84.795°, β=87.863°, γ=78.908°, V=3164.5Å3. The iron atom (nearly octahedral) was coordinated to one chelating ligand (derived from ethylenediaminetetraacetic acid) and the nitrogen of a cyanide ligand. The carbon of the cyanide ligand was bound to cobalt (octahedral). Thus, the cyanide ligand serves as a bridge between the two metals.