Success Story: Improving CBL Quality in Loss Circulation Conditions Using Low-Solids-Shear Dependent Cement System

Abstract An operator onshore Indonesia performed a remedial squeeze cement operation to help improve the quality of the cement bond based on cement bond log (CBL) results. The 4.5-in. production casing, perforated between 1850 and 1852 m measured depth (MD), showed well instability with static losses at 0.7 bbl/min and dynamic losses at 1 to 1.18 bbl/min with minimum flow rates up to 3 bbl/min. Four conventional cement slurry squeeze operations failed to yield positive results in addressing the losses because all the cement was lost to the formation behind the casing no cement was tagged inside the casing across the perforated interval. A low-solids-shear dependent (LSSD) cement system with a density of 11 lbm/gal was considered to address the challenge. This cement system reduced hydrostatic pressure above the loss zone and had tailored characteristics of early development of static gel strength. The 40-bbl treatment was pumped through an open-ended drillpipe (OEDP), with the annulus closed above the loss zone. Initially, 10 bbl were pumped to the formation, 30 bbl remained inside the casing, and 15 bbl were then squeezed behind the perforated interval using the hesitation squeeze method, followed by an eight-hour wait on cement (WOC). After the completion of WOC, the well remained static, and cement was tagged 104 m above the perforated zone. No further static or dynamic losses occurred after the cement was drilled. A successful pressure test up to 1,000 psi was performed. The repeat CBL showed improved zonal isolation and a competent barrier between the zone of interest and the water zone, which enabled the operator to proceed with the completion program without any additional treatments. The application of the LSSD cement system resolved losses on the first attempt, while four conventional cement slurry operations failed. Additionally, the LSSD cement system improved cement bond quality behind the production casing, which achieved the CBL result necessary for the operator to proceed with the well completion program.