The Research On The Technology Of The Oil Well Casing Negative Pole Protection Corrosion Preventing

DaQing Qilfield have found a total of 8245 failure casing wells at the end of 2006, which accounts for 17.1% of the all brought-in wells, and 2136 wells were replaced because of pipeline corrosion. In 2006, there were 716 failure casing wells. Along with the extension of oil field development time, the failure casing wells would be more grave, single well pipeline communication between hole occured many times , which added the difficulty in workover, pipeline patching were hard to do, especially in winter there needed digging the frozen earth, but also time is short, otherwise the pipeline would be frozen. The causes to the situation are divided into two kinds: on the one hand, the diameter of failure casing placement is small, the proportion of multi-drop failure casing wells is high, on the other hand the pipeline lost electron seriously, it could not be restored with current technology or the repair was overspending, so they were discarded even though subsurface reservoir remained production value. Adopting negative pole protection technique would safeguard steel material of many wells, extended service life of single well pipeline and oil-water wellbore, which could cut down the rate of oil-water failure casing in a certain period of time, decreased the number of replaced pipeline, reduced the investment. So without expropriation and surface pipeline laying once more, putting no impact on former well pattern distribution and development program, and unwanted renewed well, there could resume former injection-production ratio, prolong the effective utilize time of single well and finish the recovery scheme, which guarantee rate maintenance capability, and provide new preventive measure for oil field. Employing the technique could serve other oil field in domestic and foreign.The following areas were studied by this article mainly.1.Daqing oil field oil well casing corrosion mechanism and casing damage prevention2. theory and formula of negative protection.3. parameter and experiment of negative protection.4.shallow layer casing detection technique and application.The article forms a series of negative protection measure and construction method, which contains entombment and construction method of sacrificial protection, parameter choice, casing and pipeline corrosion detection, chemical corrosion prevention, dominating cement top avoidance of failure casing in batches, packer cementing external casing and so on new technique application, which provides new technique measure for prolonging service life of single well. It has been proved that the design could meet the need of single well and steel material, the design calculate could satisfy construction technique demand.Some conclusion have been obtained in the article.1.the project have created negative protection measure to DaQing Oilfield earth condition, which could prevent electron bleeding of steel in use.2.At present DaQing Oilfield Construction Group could be required to complete the construction task.3.the corrosion prevention detection agency in the Oilfield Designing Institute could detect regularly in order to master the material change of oil well and piping.4.extend the service life of oil well fully.