Development Of Building Static Gel Strength Model And Evaluating Gas Migration

With the continuous exploration and development of the new oil and gas field, the development of numerous gas fields in Northeast Sichuan, gas channeling problem becomes particularly important. A large number of practices have proved that, even if the cementing operation was very successful, during the WOC procedure, gas migration still happened now and then. Aimed at gas migration problems, studies at home and abroad generally focused on the absence of gravity caused by the development of cement slurry gel strength. But, at present, the study of static gel strength is only in its trends and how to apply static gel strength in forecasting gas migration. Even though many methods of the gas migration forecasting all used static gel strength, but current study did not establish calculation model of static glue coagulation strength, besides, at present, there is no unified standard of the static gel strength measurement.In this paper, use the Static Gel Strength Analyzer,type-5265, developed by the Chandler of USA, carry out a large number of static gel strength test experiments to the ordinary oil well cement, microsilica-admixtured oil well cement, right angle thickening oil well cement, expanding oil well cement and latex oil well cement at different temperature, pressure, thickening time, filtration and density conditions. The results show that temperature, pressure, slurry thickening time in the development of static gel strength of an obvious effect on the process; the effect of filtration and density of slurry is not very obvious on the development of static gel strength. Experimental results show that even though the right angle thickening oil well cement is showing a trend of right angle, but the static gel strength development is not a trend of right angle, as expected. In lower temperatures the difference of static gel strength between latex oil well cement and other slurry was not significant, but when the temperature exceeds 100℃, its static gel strength development apparently accelerated, and showed significant right-angle characteristics. Based on a large number of experiments, with the mathematical statistics methods, established a slurry static gel strength calculation model.In order to simplify the calculation of static gel strength, and applies it to gas migration forecasting, this paper combined effective pressure of slurry and resistance of gas migration,considering the pressure balance which decide the gas migration, prepared the program about slurry static gel strength predicting and anti-gas migration evaluating.