Law and countermeasures for the casing damage of oil production wells and water injection wells in Tarim Oilfield

Abstract

Based on the analyses of the situation and distribution of casing damage in the Tarim Oilfield, it was considered that there are six major factors causing the casing damage: (1) There are flowing rock or highly permeable formation around the casing; (2) The well bore structure is unreasonable; (3) The up hole elevation of cement in the drilling design is not high enough, or the cementing quality does not conform to the rules; (4) The quality of casing grading hoop is not up to the required standard; (5) Collapse resistance decreased due to the corrosion, wear, and special down hole operation; (6) The unreasonable development factors. According to the present situation of the casing damage, the comprehensive countermeasures of “defense”, “diagnosis”, “treatment” for repairing the casing-damaged wells were developed. For the casing-damaged wells, 3 ways, taking underground work sit sealing to suppress, engineering logging and static temperature gradient, were used to find a leakage. During 1998-2009, casing damages happened in 71 wells, and 87 places were damaged in total. After determining the position of the casing damages, 3 ways were employed to repair the casing-damaged wells, cement squeezing, using packer to the selected segment, tube expanding subsidies. Fifty-seven casing-damaged wells were repaired, of which, 46 wells were recovered on production. The success ratio is 80.70%. Key words: Tarim Oilfield, development, casing-damaged well, distribution of casing damage, casing damage prevention, countermeasure