Lost circulation is a major problem when drilling oil wells in Southern Mexico, where depths normally reach up to 7,000 meters with a fractured carbonate reservoir as the target. Very high mud losses reduces rate of penetration, increases cost of materials and induces other unwanted drilling events. Many times operators and service companies are forced to apply in-ahurry lost circulation treatments mostly based on trial and error with very mediocre success.

A Fiber system has been developed to cure lost circulation caused by the presence of natural fractures. The fiber system is deployed either in a spacer ahead of cementing or by spotting a pill during drilling. This Fiber system disperses readily in water-base fluids and is fully compatible with standard surface mixing and pumping equipment.

This field study presents the application in Mexico of this innovative and resilient Fiber lost circulation system designed to mitigate the lack of characterization of the loss zone. Fourteen jobs performed and two applications described include pumping through commonly used BHAs during drilling, and as part of the spacer ahead of the cement slurry, when partial or total losses occurred with casing on bottom.

Implementation of this engineered fiber-based lost circulation solution was extremely successful compared to the average success of other similar purpose systems. Particularly, two features were considered a breakthrough in applications while drilling: first, this solution saved 15 to 24 hours of rig time per operation as the BHA needs not be pulled out; and a second, and perhaps more important advantage consisted in being able to resume drilling quickly after pumping the material without risking to destroy the integrity of the seal. When used in a spacer ahead of cement in wells, where circulation was lost after getting the casing to its landing depth, the Fiber lost circulation solution allowed to successfully getting top of cement at the planned desired depth ensuring effective zonal isolation.