Title : From total loss to success: Innovative cementing strategies securing well integrity and zonal isolation
Abstract:
Objectives / Scope:
The cementing operation targeted the effective placement of a 7-in liner at 1,975 m across a naturally fractured interval experiencing total losses exceeding 50 m³. Key objectives were to prevent further fluid losses, achieve complete displacement of spacer and cement across the target intervals, enhance bonding and long-term sealing capability, and maintain controlled flow rates to optimize mud displacement efficiency. This paper presents the design, execution, and post-job evaluation of the case study.
Methods Procedures, process:
To address the severe loss environment, an integrated cementing strategy was implemented combining a wellbore-shielding spacer, an environmentally friendly lost circulation material (LCM) blend with plugging capacity up to 3,000-µm, expandable cement systems, and elastomer-enhanced materials to improve cement sheath ductility for long-term integrity. Flow-rate control was used to manage equivalent circulating density (ECD) and reduce induced losses. Spacer displacement efficiency was treated as a key success criterion, with spacer returns confirming effective displacement despite total losses. Extensive laboratory testing and modelling were conducted to validate slurry properties under downhole conditions, assess LCM sealing capability up to 1,000-psi differential pressure, evaluate cement expansion, and optimize casing standoff and placement simulations.
Results, observations, Conclusions:
Laboratory results confirmed that the fluids met all design requirements at surface and under downhole temperature and pressure conditions. The shielding spacer and LCM system demonstrated effective sealing performance in 3,000-µm slots at differential pressures up to 1,000 psi. The 7-in liner was run to bottom under total losses and cemented successfully. Approximately 350 m of cement was placed across the target zones with full coverage and no remedial work required. Spacer returns validated effective displacement, and the combined shielding, LCM, expandable cement, and elastomer systems delivered strong zonal isolation and improved well integrity for subsequent completion and fracturing operations.
Novel / Additive Information:
This case demonstrates a unique integration of expandable cement and elastomer-based systems with a wellbore-shielding spacer and coarse LCM to enable liner cementing under continuous total losses. The approach eliminated the need for remedial cementing, improved sealing performance, and provided a benchmark for executing cementing operations with casing on bottom in high-loss environments. The results highlight the value of material innovation and precise operational control in mitigating severe losses and ensuring long-term well integrity.
