Study On Weary Petroleum Drill Post Corrosion Loses Efficacy Mechanism And Prevention And Cure Measure

Today the mechanism studies on the failure of drilling string are mostly based on mechanics mainly in fatigue failure. But investigation from field application indicates that drilling string failure often take place prior to its normally predetermined life, even its service life are usually far less than its theoretical fatigue life. That implies that there must be some other factors which affect on the service life of drilling string. Based on data and analyzed on dissected drilling strings, corrosion stains are found in both inside and outside DP surface in the oilfields. It also reveals that corrosion may be the vital factor. Aimed at field application, on the basis of systematic analysis, failure of drilling string has been studied in detail in this paper. At the same time, for field drilling string practical application, the pipe quality inspection and deposit management have been discussed.This article indicated some ways to prevent drilling string from carbon dioxide and sulfur hydrogen. In order to reduce corrosion of carbon dioxide, some measures can be performed such as removing carbon dioxide from drilling fluid, preventing gas cutting and choosing anti-fatigue material. Through choosing anti-sulfureted hydrogen material, adding cushion fluid, adjusting PH of drilling fluid, avoiding mechanic stains, coating protection can prevent drilling string from sulfur hydrogen corrosion. Also, reasonable management, maintenance and usage are main effective factors in lengthening drilling string service life.