EXPERIMENTAL STUDY OF INCOMPATIBLE WATER MIXING AND APPLICATION OF PHOSPHATE INHIBITORS FOR SCALE PREVENTING: CASE STUDY

Scale deposition is one of the most serious oil field problems that inflict water injection systems primarily when two incompatible waters are involved. Two waters are incompatible if they interact chemically and precipitate minerals when mixed. A water injection process was effectively perform when identification of water quality and source, and laboratory compatibility tests were consider. Static compatibility tests and application of different commercial inhibitor for prevention of inorganic scale by utilizing jar tests are conventionally performed in the laboratory to avoid formation damage, but the previous studies didn’t consider the optimum specification of water/inhibitor used and didn’t investigate all of the promising scales.Obtained results from jar test for different mixing of waters can be used to know typical of scale in the reservoir. This work was undertaken to experimentally identify appropriated volume mixing of incompatibility waters for obtained maximum scale. Therefore, the type of commercial inhibitor based on phosphate and optimum concentration was obtained. Jar tests results of mixing different waters indicated that incompatibility volume mixing for maximum scales including SrSO4, BaSO4 and CaCO3 was 70% injection water to 30% formation water while for CaSO4 this amount was 80% to 20%. Also, results validated DETP inhibitor attribute to other inhibitors have high performance. The optimum concentration of DETP for preventing of inorganic scales was obtained 25 ppm. The morphology and particle size of scaling crystals formed as shown by Scanning Electron Microscopy (SEM) were also presented.

کلیدواژه ها:

water injection ، incompatibility ، Mineral scale ، phosphate inhibitors