Abstract
Recent advances in horizontal drilling techniques and completion configurations have aimed to address various challenges associated with reservoir accessibility. In an effort to optimize operational costs and improve reserves recovery through enhanced reservoir contact, operators are placing a significant emphasis on advanced multilateral wellbore configurations. However, these configurations pose significant difficulties for rig-based interventions and production enhancement operations that are heavily dependent on lateral profiling and accessibility.
An operator in North Kuwait drilled a three-legged multilateral well with the aim of maximizing reservoir contact within the Mauddud carbonate formations. This approach aimed to address various production schemes and provide versatility in the pursuit of an economical production model. As such, this completion configuration required an advanced intervention technique that relied on CT optical telemetry and a multilateral indexed entry tool (MLIET). Real-time downhole readings included casing collar locator (CCL), gamma ray (GR), CT internal pressure, annulus pressure, annulus temperature, and axial force to ensure accurate depth control, rapid lateral identification, optimal MLIET actuation, and an understanding of dynamic downhole conditions during the operation.
The three-legged multilateral candidate well had three 6 1/8-in uncased horizontal sections that required cleaning from drilling oil-based mud (OBM) and matrix stimulation using a single-phase retarded inorganic acid system (SPRIAS), which enables carbonate stimulation with superior wormholing performance compared to emulsified acid. The lateral sections had an average length of 2,100 ft and the reservoir featured a bottomhole temperature of 170°F and bottomhole pressure nearly 3,000 psi. The profiling of the three laterals was completed in less than 4 hours for each one by merging real-time optical telemetry with MLIET, which optimized rig time and treatment schedule. Prior to matrix stimulation, the three laterals were conditioned via CT through the use of a multifunctional solvent consisting of a synergistic blend of aromatic solvent and surfactants that were intended to break down and disperse OBM residuals without the need for mechanical agitation, leaving the rock water wet. The three laterals were then acidized in a single run by pumping a total of 1,200 bbl of single-phase retarded inorganic acid system (SPRIAS). In comparison with emulsified acid, the pumping time with SPRIAS was nearly 30% lower, resulting in additional efficiency for the intervention. The ability to make fast, informed decisions based on optical telemetry was the cornerstone of this intervention approach. During the initial test, the well showed a production increase that nearly doubled the operator's expectation.
This case study examines the effectiveness of a CT rig-based intervention in Kuwait, where the utilization of various technologies, including CT optical telemetry, MLIET, multifunctional solvent, and SPRIAS, allowed for the simultaneous cleaning and acidification of three-legged multilateral well. This methodology serves as a demonstration of how advanced technologies can be integrated to optimize rig-based interventions, increase efficiency, and improve reserves recovery.
