Improving the Effectiveness of Rig-Based Interventions in Tri-Lateral Oil Producers: Harnessing Advanced Coiled Tubing Optical Telemetry Fused with Single-Phase Retarded Inorganic Acid System: A State-Of-The-Art Study from the North Kuwait Field
Authors: Elaila Shams Eldin , Slama Mohamed Hedi , Badrawy Kareem , Sunagatov Rustem , Fajardo Sergio Rondon , Sebaih Mohannad Adel , Al-Husaini Mohammad Harier , Chong Mizan BinOmar , Nair Sajan Rajasekharan , Al-Mutairi Fayez Misfer , Al-Haddad Hassan 
Published: March 2024

The evolution of horizontal drilling methodologies and subsequent completion strategies has successfully tackled numerous reservoir access hindrances. As the industry leans towards optimal operational expenditure and the augmentation of reserve extraction via amplified reservoir

engagement, there's a growing emphasis on sophisticated multilateral well architectures. Nevertheless, these multilateral configurations pose intrinsic challenges to rig-based interventions, especially those heavily reliant on precise lateral profiling and access.

In North Kuwait, an operator executed drilling of a tri-lateral well, aiming for heightened reservoir engagement in both the lower and upper Mauddud carbonate strata. This strategic approach addressed diverse production paradigms while maintaining economic viability.

Consequently, this intricate completion necessitated a revolutionary intervention methodology that employed coiled tubing (CT) optical telemetry coupled with a multilateral indexing entry tool (MLIET). Real-time downhole parameters integrated casing collar locator (CCL), gamma ray, CT internal and annulus pressures, annulus temperature, and axial force, ensuring meticulous depth calibration, swift lateral pinpointing, ideal MLIET activation, and a comprehensive grasp of evolving downhole conditions throughout the intervention.

The target tri-lateral well encompassed three 6 1/8-in. bare-foot horizontal laterals, necessitating the removal of drilling oil-based mud (OBM) residues and matrix stimulation utilizing the single-phase retarded inorganic acid system (SPRIAS). This system outperforms emulsified acid by offering superior carbonate wormholing without the usual challenges, such as heightened CT friction pressure or potential emulsification complications. The lateral expanses averaged between 2,100 ft to 2,700 ft. The reservoir displayed a bottomhole temperature of 170 DegF and pressures nearing 3,100 psi. Merging cutting-edge optical telemetry with MLIET enabled profiling of each lateral in under 4 hours, significantly conserving rig operational time. Before matrix stimulation, each lateral was pre-conditioned via CT utilizing a composite solvent combining aromatic solvents and surfactants, designed for OBM residual dissolution without mechanical interventions, and ensuring the rock sand-face maintains its water wet nature. Subsequent acidification of all laterals was achieved in a singular run, deploying 1,500 bbl of SPRIAS. Compared to emulsified acid, SPRIAS exhibited a 35% reduction in pumping duration, adding to the intervention's overall efficiency. The linchpin of this strategy was the ability to render swift, data-driven decisions courtesy of the optical telemetry. Initial evaluations revealed that the production soared, outstripping operator projections by almost double.

This analysis delves deep into the prowess of CT rig-interventions in Kuwait, harnessing a slew of cutting-edge tools including CT optical telemetry, MLIET and SPRIAS for concurrent cleaning and acidification of multilateral wells. This blueprint is now being actively sought and implemented by various Middle Eastern operators to elevate their multilateral well interventions.