Study on the Theory and Method of Combined Casing Wear Resistance in Deep & Ultra-Deep Well Drilling

Abstract The high and steep structure of piedmont areas in Tarim oil field bring serious casing wear problem. Casing wear is one of the important reasons for the frequent accidents and high cost of deep & ultra-deep well. Firstly, the elements and characteristics of the casing drill-pipe tribological system input, friction components and system output are analyzed systematically. Secondly, according to the basic thought of improving tribological system input and changing the friction components to set up 6 wear prevention technological strategies including the body quality control, improvement of the casing wear prevention performance, improvement of the drilling fluid lubrication performance, changing the drill-pipe & casing friction type, improvement of the drilling speed. Thirdly, there are 11 technologies in the wear prevention technology system based on the present situation of technology, such as the vertical drilling technology, a new wear prevention technology, casing material selection, treatment of internal surface, thickening set of pipe wall, solid phase control of drilling fluid, aggravation of material optimum selection, addition of lubricating ingredient, wear prevention joint, drill-pipe protectors and rapid drilling technology. Finally, according to drilling process, 5 integrated casing wear prevention technologies are proposed, including the basic design of wear prevention, the design of expanding wear prevention, the controlling of well quality, usage of wear prevention tools, measures to remedy. These technologies made an integrated perfection of the wear prevention system, offering technical support for the synthetic wear prevention development. Introduction The situation of deep & ultra-deep well casing wear is very serious in China. Recent years, in the process of the west oilfield development, more than 10 wells, for example Kecan 1 well, Dongqiu 5 well, Dongqiu 8 Well, etc. have occurred severe casing wear and rupture or collapse accidents, which has brought serious economic loss[1]. Casing wear has become a significant technical problem must be solved in deep & ultra-deep well petroleum engineering. However, the random single wear prevention methods cannot effectively curb the frequent tend of severe accidents induced by casing wear, because casing wear itself is a complicated tribological system. Therefore, it is urgently required needs to establish an integrated casing wear prevention theory and technology system.