This paper presents the data of salt mud testing for abnormal high pressure oil wells. There were defined basic physical and chemical properties of salt solutions and their compatibility with the brine of oil deposits. It is shown that precipitation occurs in the course of preparation of well-killing fluids using the brine from oil deposits of Bashkortostan. The composition of Scale has been examined by means of X-ray phase analysis. The paper presents the results of precipitation intensity calculation by Oddo – Tomson method, considers the peculiarities of high-pressure well-killing technology selection at the deposits of Bashkortostan and offers solutions for well-killing fluids quality improvement.
The key moment for the choice of high pressure oil well-killing technologies on LLC «Bashneft» oilfields is the possibility of using formation water as well-killing fluid. However, there are a number of significant limitations. First of all sedimentation occurs when salt compositions on the chloride calcium basis with reservoir water of the Republic of Bashkortostan oilfields are mixed. According to calculations using the Oddo – Tomson technique, it has been found that the colmatant composition is complex and includes insoluble salts. The method of the X-ray phase found that precipitation can attend soluble salts-chlorides. Secondly taking into account the obtained data on water compatibility, preparation of well-killing fluid with maximum density is possible only with the use of fresh process water. The use of reservoir water for the preparation of heavy oil well-killing fluid is possible in a limited range of their required density.
Filtration tests show the negative effect of using heavy well-killing fluids on the reservoir. The obtained relative value of reduction of reservoir permeability is comparable with the effect of well-killing fluid based on calcium chloride.
References
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