Thick Salt-gypsum Layers Drilling Technology Optimization

In order to optimize the S drilling block of KYD oilfield, this paper combines the design of geological conditions and the practical difficulties encountered in the drilling and completion process in KYD oilfield to optimiz the design, through optimizing the casing program, fluid properties and the performance of the cement slurry, eventually complete the drilling smoothly.The oilfield in complex geological conditions mainly embody:formation mainly contain salt and gypsum with mud shale. So the diameter by the degree of rules greatly influence and salt water should pollute drilling mud, cement slurry and corrose the casing. Formation with high pressure system for multi-layer layer and appear alternately, thus need to design well drilling and completion. Therefor in combination with the oil field geological complex situation, on the basis of optimized casing program, optimizing drilling fluid and cement slurry is adopted in this paper to make the oil drilling and completion of construction smoothly.(1)From the casing program, the paper adopts four wellbore casing, use the technical case to solute the problem of complex problem. Although the well complex, the actual geological problems should be solved.(2)From the selection of drilling bit types, according to the different lithologic stratigraphic this paper chooses different types of drilling bit, effectively solve the complex problem in the salt formation.(3)From the mud property, using the potassium silicate polysulfide drilling fluid mixed with oil saturation and potassium salt shielding and potassium polysulfide temporary plugging drilling fluid adding NaCL and KCL, in which NaCL can inhance salt resistance, KCL plays the role to anti-rockslip.thus mud from pollution can also improve the rules of diameter.(4)From the cement slurry performance, this paper uses the cement slurry with the resistance of corrosion and salt. By using a undersaturated saline accentuate cement slurry which can be scattered in water to inhance the capacity of anti-corrosion and anti-salt. Thus this paper can solved the question of gas migaration in difference layer.Through the optimization design of drilling in this region, the optimization design is suit to the area, and which can smoothly drill and can make for the life of the well.