Matrix acidizing

The type of data produced in a f.a.b. experiment is affected by the pH and ionic strength of the matrix. The former may be controlled either by the addition of acids or bases, although, in practice, it is usually preferable to keep the matrix acidic. The ionic strength is partly dictated by the purity of the sample (many biological compounds are still contaminated with salts, even after extensive purification) and partly by exogenous additives. Three additives are especially useful for carbohydrate work. They are as follows. 

Matrix acidizing is the injection of acids into the formation at a pressure below the formation parting pressure (the pressure at which natural fractures are forced open by injected fluids). 

The aim of a matrix acidizing job, which, in carbonate reservoirs, generally consists in injecting plain hydrochloric acid at pressures below the formation parting pressure, is to decrease 5 down to zero. 

Matrix acidizing treatments are more often performed, nowadays, with sensors and data acquisition systems continuously recording the surface pressure and rate histories. According to a recently proposed methodology (15), these records can be used to compute downhole rate and pressure evolutions. The bottomhole pressure history is then compared to the theoretical response of an equivalent reservoir wherein a non-reactive fluid would have been injected according to an identical rate schedule. Following this method, the difference between both theoretical and actual pressure responses originates from the evolution of the skin of the true reservoir under the influence of the acid attack. Equation 1 is then used to derive the skin decrease from this pressure difference. 

Silica-alumina gels containing 20-45% alumina provided the best combination of activity and activity stability. Therefore, we chose a gel with a composition in this range for binding the system together and as the matrix acidity ingredient. 

The catalyst must also have acidity in the matrix in order to reduce the molecular weight of molecules too large to enter the zeolite and in order to also convert heavy-cycle oil to light-cycle oil. Our studies have established that good balance in acidity between the matrix and the zeolite tends to enhance selectivity. A stable matrix acidity is also required, and here a high alumina silica-alumina cogel was selected due to its demonstrated stability in the pre-zeolite era. Certainly many other acidic matrices could probably be substituted. 

Figure 3. TLMs of extrusion texturized pH-modified soy flours (I) pH 9.0 (2) pH 8.0 (3) pH 6.6 (4) pH 5.6 (5) pH 5.3 extruded at LFR (6) pH 5.3 extruded at HFR. Note that alkaline pH could increase the fihrousness of the protein matrix acidic pH produced the opposite effect. P, protein C, insoluble carbohydrate.

Water, soil, sediment, fly ash, fuel oil, sludge, still bottoms, fish, adipose Addition of 13C-labeled standards followed by solvent extraction (exact method depends on matrix), acid-base washing treatment, solvent exchange, and cleanup using alumina, silica gel, and activated carbon, addition of Relabeled internal standards. HRGC/HRMS (MIM) (EPA Method 8290) 10 ppq for water to 1 ppt for other matrices (depending on complexity) No data EPA 1994c... 

Matrix acidizing (acid squeeze). Acid is squeezed into the formation matrix including the pores acid penetrates and enlarges flow channels and dissolving plugging particles. 

Table 6 shows a comparison of opiate concentrations in hair, together with coefficient variations obtained by SFE and by other extraction techniques. It can be seen that methanolic extraction gives good results with the exception of morphine, where the extraction yield appears poor ( 60% of the amounts obtained by SFE). This could be a result of the polar nature of morphine, which must be more solidly fixed on the matrix. Acid hydrolysis and basic hydrolysis are of little interest, because 6-MAM, which is effectively found in high quantities in hair, is destroyed during the procedure and is partially transformed into morphine. 

Matrix Acidization. Emulsion technology has been applied to the acid treatment of reservoir material in the region near the well bore. The pore structure of the region of the reservoir near the well bore may sometimes become plugged either by particulates from drilling fluids or by pre-... 

This matrix acidization process consists of injecting hydrochloric acid (for limestones) or a hydrochloric acid-hydrofluoric acid mixture (for sandstones) into the formation pore space. The acid reacts with and dissolves portions of the original rock matrix and thus increases permeability. The depth that the acid penetrates into the formation is one of the factors that determines the effectiveness of the treatment. 

The emission spectrometer is interfaced to a programmable calculator (Model 9830, Thermal Printer 9866, Hewlett-Packard, Mississanga, Ontario). During calibration raw millivolt data of the matrix acid blank are subtracted from the standard data. Slopes and intercepts are obtained through a second-order polynomial regression. Dming analysis all data listed on the thermal printer and stored on the %-in. magnetic tape cassettes is in solution concentration units with appropriate sample... 

The major problem in food analysis is the complexity of the matrices. For example, coffee has a complex matrix. Acids from coffee are important for the sensory quality of the coffee beverage. For every acid identification, it is necessary to perform an electrophoretic cleanup of all organic acids followed by the use of the GC-MS technique.34... 

Foamed Matrix Acidizing. Matrix addizing is a stimulation treatment used to remove damage near the wellbore without deating a fracture. The process involves the injection of a reactive fluid into the porous medium at a pressure below the fracturing pressure. The fluid dissolves some of the porous medium and consequently increases its permeability. 

A larger volume of acid is needed to conduct the matrix-acidizing job... 

The intimate dispersion of the salt in the matrix is also important (35,36) if the salt is not well dispersed, there may be a loss of signal. The matrix is often an organic acid. By making the salt of the matrix acid and mixing this with the parent matrix acid, increased polymer signal is obtained. Too much salt, however, leads to no polymer signal since matrix salt alone is often not a good matrix for the poljmier. 

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