Browsing by Subject "Hydrochloric acid"
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Item An In-depth Investigation of an Aluminum Chloride Retarded Mud Acid System on Sandstone Reservoirs(2012-07-16) Aneto, NnennaSandstone acidizing using mud acid is a quick and complex process where dissolution and precipitation occur simultaneously. Retarded mud acids are less reactive with the rock reducing the reaction rate hence increased penetration into the formation to remove deep damage. To understand thoroughly the retarded mud acid system, an in-depth investigation of the reaction of HF (hydrofluoric) and H2SiF6 (fluorosilic acid) with alumino silicates and the retarded system is undertaken using coreflood analysis and mineralogy analysis using the inductively coupled plasma. Coreflood analysis is used to understand and investigate the permeability changes in the sandstone rock as the retarded mud acid is injected at different conditions and the inductively coupled plasma (ICP) is used to investigate the effluent samples from the coreflood analysis to properly understand this system. Several issues that have not been addressed previously in literature are identified and discussed, including an optimum flowrate when sandstone is acidized, by acidizing the sandstone rock with a retarded acid system at various flowrates and determining the initial and final permeabilities. Also investigated is the retarded acids compatibility with ferric iron and a comparison of the retarded acid system to regular acid to consequently enable a thorough understanding of the retarded mud acid system using aluminum chloride (AlRMHF). Based on the work done, it is found that the absence of a hydrochloric (HCl) preflush is very detrimental to the sandstone core as calcium fluoride is precipitated and the retarded acid system is found to be compatible with iron(III) as an impurity. The regular acid (RMHF) dissolves considerably more silicon and produces more fines than the AlRMHF. 1cc/min is found to be the optimum flowrate when a sandstone core is acidized with AlRMHF. At this low flowrate, less silicon is dissolved, more aluminum is seen in the effluent and more calcium is dissolved. The retarded aluminum acid system considerably reduces the rate of reaction as evidenced in the dissolution reaction when compared to a regular mud acid system. This reduced rate of reaction implies deeper acid penetration and ultimately deeper damage removal.Item Development of new automated flow titration systems(Texas Tech University, 2004-08) Jo, Kyoo DongTitrimetry is one of the oldest analytical methods still in use. It is probably the analytical technique that has changed the least over the years. It remains one of the most widely used tools for making high precision measurement. In classical batch mode titration procedures, the volume of titrant added to a titration vessel is the variable that is controlled and monitored and subsequently used to calculate the original analytical concentration in the test solution. More advanced and automated batch mode titrators have been developed. However, the downside of titrations in conventional batch mode are significant reagent consumption and poor throughput rate. Thus, automation of titrations using the continuous flow mode has been increasingly drawing attention. The new concept for continuous on-line titrations based on feedback-controlled flow-ratiometry and the principle of compensating errors creates a new paradigm for flow titrations by feedback based flow ratiometry in which the delay between the sample-titrant confluence point and the detector is made constant. The error due to lag time is continuously compensated for by averaging rapid backward and forward titrations. This new concept has been developed and applied to titrations followed by potentiometry and photometry. Electrogeneration of titrants have several significant advantages. The most important of these is the elimination of problems associated with the preparation, standardization, and storage of titrant solutions. This advantage is particularly significant when dealing with unstable reagents. Electrogeneration of the titrant allows the transformation of the newly developed error-compensated feedback based flow-gradient method into a concentration gradient method. Coulometric titrant generation transfers the control from the flow control to current control. This system has been applied to various redox titrations using photometric and potentiometric detection methods. An additional new type of flow injection titration system has been developed based on a syringe pump. In this system, the titrant is injected in a triangular programmed flow pattern by a syringe pump in a continuous stream of the sample. This new type of flow injection titration method was applied to acid-base and redox titrations, and the data interpreted by the principle of compensating errors.