Performance Evaluation of Lightweight Oilwell Cements

Drilling through depleted zones and weak formation can prove troublesome since the fracture resistance reduces from its normal boundary [1]. To successfully drill a hole section requires the selection of a low density cement slurry to prevent loss circulation while not exceeding the fracture resistance of the formations exposed. Large number of loss circulation will greatly impact the drilling cost and rig time. This research is focusing on the performance studies of lightweight oilwell cements using foam and cenosphere as the lightweight agents. All tests were conducted according to API Recommended Practice 10B-2. Three performance tests have been conducted such as density test, free water test and compressive strength test. The comparison was made at different percentage of lightweight agents e.g. 10, 20, 30 and 40 percent by weight of cement (%BWOC) respectively. The findings show the performances of formulated foam cement and cenosphere cement are within API limit. However, foam cement can reduce the density of set cement in about 8% greater than the cenosphere cement.