Assessment of pressurized foamed cement used in deep offshore wells
The National Energy Technology Laboratory (NETL) in conjunction with industry partners began a project to assess field-generated foamed cement at pressurized surface conditions. The collected samples were compared to previous field-generated samples as well as equivalent samples generated with current laboratory protocols following the recommended practices in American Petroleum Institute's Recomamended Practice (API RP) 10B-4; atmospherically generated. In-situ samples of foamed cement were successfully captured in constant pressure (CP) cylinders under field conditions and analyzed while under pressure using multi-scale computed tomography (CT) scanning. The comparison of laboratory and field samples addresses changes to the cement under in situ conditions. Initial results highlight key differences in laboratory and field-generated foamed cements. Results of laboratory testing indicate a correlation between bubble size distribution, permeability, and strength. Field-generated samples show changes in pressure significantly influence the bubble size, while the flow of the slurry into the pressure cylinders created less homogeneous cured foamed cement. This paper discusses further research of in-situ field generated foamed cement behavior. These data provides insight to support the ongoing effort to help predict a method to correlate testing for foamed cement performance in the laboratory that would compare to more representative field behaviors.
