Expro Inc.

The Vaca Muerta formation ranks among the most productive formations in the Neuquén Basin and plays a key role in regional energy economy, during well development of tight formations, casing deformation events are frequently detected, with high impact due to fracturing processes (Vítolo et al.,2025). In order to properly address these events, a thorough understanding of their characteristics is required. One of the main challenges lies in accessing the horizontal section of the well, where wireline services—commonly used to convey logging tools—are unable to reach the required horizontal depth. In such cases, alternative conveyance methods, such as coiled tubing or tractor, must be employed. Coiled tubing was used in the three wells analyzed in this study. Characterizing a deformation represents the first step toward determining an effective solution, allows the definition of the new drift diameter in the affected section of the downhole completion, with the ultimate objective of designing a new tool string capable of reaching the target zone and enabling a redesign of the well completion. It is well known that casing deformation events limit reservoir accessibility and, in many cases, prevent well completion and subsequent production stage. Moreover, the strategies and attempts to address these issues may lead to ambiguous outcomes if they are not supported by accurate diagnostic information. A detailed understanding of the preparation procedures for the Multifinger Caliper (MFC), aimed at acquiring high-quality data, in accordance with data validation mechanisms, tool string design—which may vary depending on whether a Pipe Analysis Deformation (PDA) is planned—and operational considerations derived from experience in conveying the caliper via coiled tubing to pass through deformed intervals, provides invaluable guidance when addressing these operational challenges.

The concept of utilizing an expandable liner is presented to restore casing integrity when unexpected casing damage occurs during well stimulation. This solution allows the operator to continue with additional planned frac stages with little downtime or changes to the overall operational plan. A solid expandable liner is a specially designed casing string that is cold-worked downhole to plastically deform the casing and make it larger than its run-in-hole OD. It has metal seals on the OD of the casing that provide a pressure seal and anchor the new casing string/patch into the existing casing to isolate casing damage. The planning and preparation process is discussed including boundary conditions, diagnostic procedures such as cased-hole logging and wellbore cleanout, followed by the installation process of expanding the liner at the given setting depth. The expandable liner solution is compared to more traditional solutions for addressing casing damage during well stimulation, such as cement or resin squeezes and conventional liners. Six field case studies are presented showing different scenarios where unexpected casing damage occurred during fracturing operations and an expandable liner was used to restore casing integrity and allowed the frac operation to continue. Expandable liners are an innovative solution that can help save operators rig time and money while providing a permanent repair that still has a large enough pass-through ID and high enough pressure ratings to allow the well stimulation and completion to be executed as planned without deviation to pressures or equipment sizing.

The quantitative characterization of faulting and folding in sedimentary basins is crucial for understanding the relationship between architecture and kinematics at upper crustal levels. A kinematic model of classic fault-bend folding provides a quantitative relationship between fold geometry and fault movement, making the growth strata with upward-narrowing kink-bands a complete, decipherable record of deformation. When folding is produced by material being transported along a bumped detachment fault (an original flat detachment layer folded), the geometry of the growth strata becomes complicated; thus, its quantitative relationship with detachment displacement is unknown. This folding model, here called “bump-type fault-bend folding”, is well exemplified by the Shenghe 2 structural belt in the West Kunlun Cenozoic foreland thrust system. Seismic interpretation indicates that the growth strata in this case are characterized by lateral thickness fluctuations, which indicate folding of the detachment layer. Combined with kinematic forward simulation and structural trend analysis, we noted that the migrating distances of the lateral thickness fluctuation zones in various growth sequences reflect their experienced detachment displacements. The application of these findings to the Shenghe 2 structural belt reveals an early Miocene folding event of the basal Cenozoic detachment, four subsequent detachment slip increments, and clockwise transport of the Cenozoic thrust sheet. The quantitative kinematic model of bump-type fault-bend folding and the method presented here may have widespread applications in dating the folding of detachment layers and reconstructing the slip history and orientation of thrust sheets.

Geothermal wells, particularly in high-enthalpy hot water systems with injector-producer configurations, are subject to thermal and geochemical stresses. High-formation temperatures and corrosive components, as dissolved CO2, H2S, and chloride-rich brines, can reduce the effectiveness of conventional chemical treatments. These conditions accelerate localized corrosion processes, including pitting and crevice attack, that compromise completion integrity. A technology-driven remediation strategy is critical to extending well service life and ensuring long-term sustainability of geothermal assets in the context of the energy transition. This paper presents a case study detailing an advanced well integrity remediation executed using hybrid coiled tubing technology (HCTT), by integrating both electric conductor and distributed fiber optic sensing (DFOS) functionalities. The presence of the electric conductor enabled deployment of a high-resolution multi-finger caliper for accurate casing damage characterization and powered a real-time monitoring BHA, eliminating battery constraints during critical operations as patch setting cycles. Concurrently, the integrated fiber-optics enabled DFOS acquisition immediately post-patch installation, providing real-time thermal and acoustic surveillance for leak detection, eliminating the need for pressure testing, a key advantage in this scenario where applying pressure could have imposed excessive mechanical load on the casing, potentially leading to structural failure. The intervention was engineered into the following phases: Casing Preparation, in-situ mechanical cleaning via abrasive slurry jetting to remove rust, scale, and debris from the casing surface, to ensure patch-to-metal contact, improved caliper data, and eliminated the need for mechanical standoffs; Damage Diagnostics, high-resolution electric multi-finger caliper to localize and quantify casing defect; Restoration and Integrity Verification, deploying an inflatable casing-patch, followed by DFOS acquisition to validate mechanical setting and hydraulic isolation. To enhance thermal signal contrast for real-time DFOS interpretation, a temperature differential of approximately 30-40 °C was induced between the well and the annular injection fluid. This was achieved by implementing a cryogenic cooling loop—a serpentine assembly of hoses through which liquid nitrogen was circulated—allowing the injected water to be sufficiently cooled. Potential thermal anomalies were captured via DTS, while DAS responses were stimulated by flow noise, collectively enhancing the detection sensitivity across the repaired interval. The HCTT-based workflow enabled precise diagnostics, effective mechanical remediation, and real-time, non-invasive integrity verification. DFOS acquisition provided high-resolution leak detection without applying mechanical stress to compromised completion. This case confirms the technical and economic viability of full-spectrum HCTT as a scalable, non-invasive solution for long-term well integrity management in high-temperature, high-corrosivity environments. The flexibility of HCTT proved to be a key advantage, enabling the Operator to execute the remediation workflow, without mobilizing additional service providers. Real-time DFOS immediately after patch installation enabled efficient and non-intrusive verification of well integrity, eliminating the need for pressure testing and avoiding mechanical stress on the compromised completion.

As fields mature and move into late life, it becomes increasingly difficult to identify and produce the final remaining barrels. Different reservoir displacement and recovery processes over many years combined within heterogeneous flow unit properties significantly increase the fluid's uncertainty. Surveillance is essential to help identify potentially bypasses hydrocarbons. In high water cut low oil rate mature wells, perforating bypassed oil can have a significant impact on improving well performance. In this case, study in the Beryl field, there has been a combination of gas and water displacement along with displacement of varying salinity water. Some wells have historic pulsed nuclear logs while other wells have no reference logs at all. Because there is the potential for both gas oil and water within individual sand units, a variety of pulsed nuclear techniques were used to evaluate the sands. This included traditional sigma, inelastic ratio, capture ratio and carbon-oxygen. Synthetic initial and swept logs were also generated as references to help with the evaluation process. To increase efficiency and reduce costs, pulsed nuclear logs were gathered in a number of wells and evaluated within hours of gathering data allowing for the immediate perforation of any bypassed intervals during the same visit to the well. In addition, the ability to isolate water-producing sands was also considered. Significant additional production was added using this approach resulting in an initial increase of over 10,000 bbls/day in the 3 wells used in the case study. Pulsed nuclear surveillance utilizing multiple nuclear attributes resulted in significant improvement in oil production in this complex reservoir with mixed salinity.