EVALUATION OF WATER QUALITY TO IMPROVE INJECTIVITY OF PRODUCED WATER IN A WATERFLOODING PROGRAM: A CASE STUDY FROM MELEIHA FIELDS, WESTERN DESERT, EGYPT
The performance of waterflooding programs is firmly attributed to management of injection water quality, particularly scale tendency and total suspended solids. Poor injectivity not only deteriorates sweep efficiency and inconsequence reduces the overall recovery, but also results in inevitable stimulation and other costly workover jobs. In this research a detailed water quality assessment for injection water plant in Meleiha fields is discussed to determine the requirements that ensure the reliability of injection program. Two water sources and their mixtures are considered; water producers from Kharita formation and the produced water separated at API separator. Results indicates that the scale tendency (ST) analysis of various mixtures showed values less than one indicating under-saturation conditions that generally hamper scale formation. In addition, barite and calcite reported the highest ST among the feasible scales to form and the ST indices for barite and celestite tend to decrease with the decrease of formation water share in injection water mixture while increasing for calcite and gypsum. Under reservoir conditions, ST is significantly lower than the corresponding value at the surface conditions for Kharita/produced waters and their mixtures at the various mixing ratios. Compared to the water from Kharita aquifer, the produced water obtained has poor quality and shows high plugging tendency and should be thoroughly managed. In addition, bacterial activity was detected and should be suitably treated. The detailed analysis helps to formulate various water treatment stages in a preliminary conceptual design for water injection plant that could assist reducing water injection problems and maintain successful waterflooding.
injection water quality, scaling tendency, injection plant design, waterflooding
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