A Technology Study Of Leakage Proof And Plugging Cement Slurry

Because of the low stratum pressure coefficient and the development of stratum with fracture in Haituozi of Jilin Oilfield, almost every well has taken place in different levels of lost circulation in this area. In the process of cementing, different degrees of leakage phenomenon have occurred. In this area, the leakage has become a big difficult technical problem of oil and gas exploration. Other blocks in Jilin Oilfield, like Daqingzi and Honggang, the situations of are also similar to this block. Presently, low-density cement slurry system which uses in these areas has a good leakage proof feature, but it also exists some problems, such as: volume contraction of cement stone, high brittleness and low compressive strength etc. In view of the above question, we have developed fiber toughening cement Slurry system. This system can improve the flowability of cement flurry, also can significantly reduce the water loss and bleeding rate. Moreover, it's thickening time can be adjusted and thickening curve is standard. Under the same conditions, mixing fiber toughening cement slurry to maintain 48h, compare to pure cement slurry ,its static elastic modulus reduces 46%～61%, the anti-impulse increase 53%～32%, anti-fold strength increased 18%～33%, The cement-stone compressive strength is more than 19.0MPa equally. This cement slurry system simultaneously has many good characteristics, such as: leakage proof, toughening, high strength, low filtration, no bleeding water and good rheological property etc. According to the field test in the Sea 32 production casings, the Sea 36 intermediate casings and in production casings, we find that it has a very good leakage proof and plugging effects. As two times obvious leakage have happened when Sea 32 production casing cementation has had, and four times obvious leakage have happened when the Sea 36 intermediate casing cementation has had, but because the different size and different type of textile fiber's joined ,which builds a web forming and filling property, that played the obvious plugging role. According to the explanation of logging sound amplitude, Sea 32 and Sea 36 well is high quality,and the wells cementation quality merit factor has achieved 100%. Afterward, in Daqingzi and Honggang blocks, promotion has applied 40 wells, has made a good application progress.Both indoor and field test showed that the kind of slurry system will not only meet the engineering requirements, but also has good leakage proof, plugging and toughening effects. This technology successful application in the Jilin Oilfield, not only solved the problems that the easy leakage areas and the long isolation section leakage of cementing, but also has provided the excellent cement sheath for the oil well. It has provided the technical support for the oil well long-term production and for the technical support in the large area development of Haituozi. It has provided a new way to solution easy leakage block in Jilin Oilfield and other close sub-area, for example, Haituozi block.