| The problem of surface gas migration is a common and dangerous one. Its presence can prove to be not only a nuisance, but more importantly a serious source of well control problems. Consequently, an understanding of the underlying factors associated with this problem as well as developing successful solutions for it is an important issue for drilling and completing oil wells.;Gas channeling through a column of cement is most prevalent during its transition from liquid to solid. During placement and while the cement is in a liquid state, the main factor prohibiting the gas from entering the cement is the hydrostatic pressure of the cement column and the original well fluid (if not cemented to surface) above it. As long as this hydrostatic pressure is greater than the pore pressure of the gas - bearing formation, gas will not percolate through the cement. The problem becomes complex because cement will not remain indefinitely a liquid; it will eventually become hard. As the slurry begins to hydrate, it becomes a gel-like material and loses its ability to transmit its full hydrostatic pressure. If the cement slurry is incorrectly designed, this can lead to an influx of gas.;This thesis explores the design, execution and evaluation of an impermeable slurry that utilizes a novel low temperature latex fluid loss additive which prevents annular gas migration in oil well cements. It will evaluate slurry properties such as the static gel strength, fluid loss, compressive strenth and thickening time to determine its effectiveness at preventing gas migration. The slurry will also be tested in an actual well and its performance noted. |
