Advanced Lost Circulation Solution: A Highly Thixotropic Cement System Pumped through BHA for Efficient Lost Circulation Management
Authors: AlSayed Omar F. , Ibrahim M. , Pullanikkottil S. , Mesilhy M. , Farouk E. , AlEnezi D. , Gholoum S. , AlQattan M. , AlQadhi F. , AlShayji A. , AlSafran S. , Monteiro K. 
Published: October 2024

Lost circulation is a major challenge in well drilling and can cause well instability, increased costs, or even well abandonment. Many methods have been tried to deal with this problem, but it remains a serious issue worldwide. The goal is to address various lost circulation scenarios in drilling operations and reduce non-productive time, which will improve rig efficiency and well economics. The Advanced Lost Circulation System has many technical advantages over conventional slurries for loss circulation control and offers a more effective solution to overcome this challenge in drilling wells.

A conventional cement plug operation can take up to 48 hours to finish, including trip time, WOC and other steps. Sometimes, multiple plugs are needed, which increases the non-productive time. The Advanced Lost Circulation System is a better alternative that can be pumped through the BHA and can reduce the nonproductive time to as low as 6 hours per job. Advanced Lost Circulation System is specially designed to stop losses while drilling, ranging from seepage to total losses. It has low solids and rheology during pumping, which allows it to penetrate deep into the loss zones and form a gel when the shear rate drops. The gel has high static gel strength and early compressive strength, which helps to seal the thief zones, prevent further losses, and prepares the wellbore for primary cementation. Advanced Lost Circulation System has a low density (~10 lb/gal), a low sensitivity to temperature changes, and compatible with both water and oil-based drilling fluids. The Advanced Lost Circulation System is also acid soluble.

The study investigated the properties and performance of the Advanced Lost Circulation System, a slurry that exhibits high thixotropy and re-pumpability. The slurry was designed to overcome the challenges of lost circulation. The laboratory tests showed that the slurry could rapidly gel when the shear stress was reduced and resume its fluidity when the shear stress was increased. The field trial demonstrated that the Advanced Lost Circulation System successfully cured the lost circulation zones and enabled a primary cementing job of an intermediate casing with good zonal isolation and casing protection. The cement reached the surface and the CBL confirmed the quality of the cement sheath. The study proved that the Advanced Lost Circulation System is an effective solution for lost circulation problems in oil and gas wells.

Lost circulation can cause significant economic losses due to wasted mud, extra rig time, fluid system adjustments, additional materials, and possible well abandonment or sidetracking. The Advanced Lost Circulation System has technical advantages over conventional systems to address all above. It can create a low-permeability filter cake that seals fractures and prevents fluid loss. The Advanced Lost Circulation System can also improve drilling efficiency and performance by reducing torque and drag, enhancing hole cleaning, and stabilizing the wellbore. The Advanced Lost Circulation System is a cost-effective and reliable solution for drilling operations that face lost circulation challenges.