The operator’s main objective was to increase oil production in the Kissenda Reservoir with improved producer and injector wells. For four years, a third-party company provided cementing services, but the quality of cement logging varied from poor to fair. In the beginning of the operation, wells still produced 30% to 90% of water. Water zones were as close as 10 m from oil zones. SLB and M&P reviewed past well logs and found that the sections of the logs showing poor cement were close to water zones.
The operator and SLB concluded that the problem was a postplacement invasion of high-pressure water in addition to thick filtercake. The strategy was to apply the CemPRIME Scrub engineered scrubbing spacer to clean the casing and formation walls. The cement slurry was designed for a transition time as short as 10 min. This was achieved through the integration of microfine cement in the design.
CemPRIME Scrub engineered scrubbing spacer scoured the wall of the casing and formation, removed the gelled filtercake layer, which created a stronger bond for the cement. The addition of microfine cement in the slurry increased solids content without affecting the density. That design generated a shorter transition time that gave the slurry greater resistance to water invasion post placement. This approach was successful on three consecutive wells, and water production was cut to 1% in each case. Based on this success, the customer extended the SLB contract for an additional 13 wells.
