Cementing Technology Applied in the Parahuacu Oilfield of Ecuador

When cementing a well in the Parahuacu oilfield of Ecuador, edge-bottom-water channeling is very likely to occur in the second interface in which cement slurry filtrate and solid particles easily intrude into the reservoir pore throat, and cement slurry with conventional density may leak into the reservoir. To solve those problems, an acidic flush fluid, a temporary plugging spacer and an interfacial cementing enhancer were developed through simulated flushing tests. Keeping those factors in mind, a multi-effect cementing pad fluid was prepared with them. A low-density cement slurry containing anti-channeling latex was developed with a micro hollow glass ball while considering the liquid-solid ratio, fluid loss control and anti-channeling performance. Indoor testing results show that by using the multi-effect cementing pad fluid, 95.0% structural mud cake on the sidewall was removed, the permeability recovery of the reservoir reached over 90.0%, the interfacial cementing strength increased more than 5 times. The cement slurry with anti-channeling latex has a density of 1.74 kg/L, its performance is stable, API fluid loss does not exceed 20 mL and static gel strength transition time is less than 10 min. The newly developed cementing technology, including the above-mentioned pad fluid, cement slurry and relevant supporting technical measures (such as centralizer placement, displacement scheme design), was then applied to 5 wells in Parahuacu oilfield. In the field application, casing centralization was up to 85.8%, annulus displacement efficiency of cement slurry exceeded 95.0%, no leakage of cement slurry or edge-bottom-water channeling was found in the reservoir. The new cementing technology in the Parahuacu oilfield has achieved significant effect and can solve existing problems in reservoir cementing.