Abstract
A review of lost circulation plans, contingencies, recaps, and methods used to primarily prevent losses in the upper-hole sections drilled in the offshore region of the Arabian Gulf was compiled in an effort to ascertain which lost circulation treatments and/or combinations were historically effective or ineffective for regaining circulation especially after total losses, whereby total planned depth was achieved with little to nil non-productive time (NPT) as related to drilling fluids. This evaluation highlighted numerous inconsistencies and excessive time committed to combating losses whereby the critical path was marginalized. While these wells comprised sole objectives, their upper-hole sections were drilled through known troublesome formations often with the same result. It was surmised that the type of lost circulation material (LCM), combinations of LCM, and frequency of use contributed little to no benefit in particular circumstances. Subsequently, this review was undertaken to ascertain if time could be saved with more prudent utilization and/or tactics when utilizing LCM to combat losses.
A well-known application of LCM is its usage as background solids to mitigate fluid loss in troublesome wellbore sections primarily due to the relatively inexpensive cost, availability, ease of use, and compatibility with the drilling fluid. LCM are supplied in a myriad of sizes, types, textures, and applied in varying concentrations and combinations. This review details numerous LCM types and combinations in addition to various pills. While attempts were successful in stopping losses in the upper-hole sections, success was sometimes temporary as subsequent drilling operations would, in some cases, realize losses greater than the established trigger rate.
The ensuing discussion includes a synopsis of challenging vugular and/or fractured carbonate formations in the UAE and Copper Ridge Formation in the US, a review of common and some uncommon LCM, the field results, and finally, lessons learned and strategies are propositioned. The selected LCM are contrasted with their application in formations of the upper-hole sections versus various loss scenarios and results.
