The Study On Hydro-mechanical Joint Casing Scale Removal Technology

In recent years, as the exploitation of most oil fields in China came into anapHase stage,many oil and water wells have a problem of scale. Especially the hard scale and not dissolvedto acid scale, which is hardly to remove by conventional methods such as chemical method.The scale will build-up on the casing and tubing, and cause a series problems to the operationof the oil field such as casing internal diameter will get smaller and the tools can’t passthrough.In this paper the mechanism of oil and water scaling is studied first, the results show thatas the high salinity of formation water when the environment temperature and pressurechanged and when the two different formation water mixed, the scaling will happen. Theformation water’s salinity of Dongxin oil coMPany is very high, so there are serious scalingproblems during the production. Most scale of Dongxin oil coMPany is CaCO3, and there issome FeO also.In order to remove the scale on the casing, two kinds scale-removal tools are designedwhich is non-rotating hydra-mechanical scraping type scale-removal tool and drilling typescale-removal tool. And also the material of the tool is chosen, the structure of the rotatingnozzle is optimized and the tooth arrangement of scale-removal bit is designed. On the baseof these design, the rotation characteristics and the pressure pulsed characteristics of therotating nozzle and the scraping characteristics of the non-rotating hydra-mechanicalscraping type scale-removal tool is experimental tested, and the matching process parametersto the tool is determined; the hydraulic parameters of drilling type scale-removal tool isdesigned also in this paper.At last the field experiments are done in nine wells of Dongxin oil field, four wells inwhich the drilling type tool is used and four of which the scraping type tool is used, in the lastone drilling type tool is used firstly and then the scraping type tool is used. All of these ninewell got a good descaling effect. The experiment result show that the design of two kind tools is viable and these two kind tools can be accepted by the oil field.