Customers in Ecuador inject the byproduct formation water from production wells into injector wells. A limited injection rate bottlenecks production, which is economically undesirable. Two major contributors limit injection capacity: reservoir injectivity and flowline pressure losses. In the latter case, paraffins, asphaltenes, and scale, collectively referred to as "schmoo," progressively build in the flowline and reduce the internal diameter, limiting flow rate capacity. One cost-effective method to remediate flowlines with significant deposits is coiled tubing (CT) cleanouts. This unconventional method, which calls for optimized planning, execution, and performance evaluation, has been implemented in five flowlines. An economic analysis shows that remediating flowlines using CT cleanout yields significant savings as compared with replacement. After a candidate is identified, job planning takes into consideration flowline length and deviation (to identify maximum reach of CT), schmoo analysis (to design an optimal bottomhole assembly and fluid treatment), and execution logistics (to ensure a viable, reliable, and safe operation). After the cleanout, the flowline is put back into service, and the effectiveness of the treatment is estimated based on system flow rates and pressure losses. The equivalent internal diameter (ID) for the flowlines was improved by over 49% in each of the remediated flowlines, achieving an effectiveness of over 89% of nominal ID and increasing flow rates without a detrimental effect on system pressure. The cleanouts re-established nominal capacity in over 50k ft of flowline that no longer needed replacement. Lessons learned include the ability to complete the cleanout with water alone. The chemical analysis in planning stages showed the absence of carbonates, which enabled a mechanical cleanout with a high-pressure nozzle. Nonetheless, a chemical treatment was designed as a contingency. Another learning was that whereas tubing force models helped predict the reach of the CT, other factors created limitations. For example, the weld bead on the flowline limited the reach of the CT and required re-evaluating where to create cuts along the flowline. Finally, deploying the CT in a flowline required configuring the injector head horizontally, which required a customized base for safe rig up and operation of the injector head and pressure-control equipment. CT successfully cleaned out five flowlines with IDs ranging from 6-in. to 8-in. and re-established 89% to 98% of their nominal ID. As a result, the operator saved upwards of USD 14 million in flowline replacement costs, increased asset utilization, and decreased deferred injection. Historically, there is limited documented experience with flowline cleanouts using CT. The paper documents a repeatable methodology for candidate selection, planning, execution, and performance evaluation. It also provides basic building blocks to meet treatment design, rig-up, and execution requirements that are unique to this application.

The abundance of digital calibration information can be leveraged through statistical mining to improve calibration methodologies in tool manufacturing. Historical tool metrology, unable to store massive data, relied on easily processed, summary performance metrics. However, with modern computing power, more computationally expensive methods of large data sets can be used to refine tool and process metrology, accuracy, and reliability. Empirical data from large sets of quartz memory gauges suggest that tools are consistently outperforming the accuracy specification derived from historical static calibration. This paper presents an alternative metrological methodology that provides additional insight into the accuracy of calibrated gauges. An analytic framework based on the Satterthwaite confidence interval (CI) is developed using an unpaired sample t-test and simultaneous field measurements from five stable pressure segments are used to validate the predicted variances between gauges. The methodology significantly improves measurement accuracy and reliability and is applicable to any instrumentation that undergoes a consistent, repeatable, and linear calibration.In addition to reevaluating existing tool specifications, the methodology can be integrated into metrological practices in the oil industry where large digital data sets and painstakingly accurate tools and calibration devices are commonly found. Presented are results from memory gauges, but by extension the method is applicable in other formation evaluation endeavors. The analytic framework predicts a factor of proportionality between the accuracy predicted by the CI and the traditional metrics of individually calibrated gauges. Specifically, a relationship is found between the 2-norm of the mean quadratic deviation (MQD) error of two individually calibrated pressure gauges. A case study of high-pressure, hightemperature (HPHT) gauges in five well tests in the North Sea and India confirm analytic predictions. The paper focuses on quartz memory gauges and improves absolute and relative accuracies of HPHT gauges by over 33% and 56%, accordingly. Comparable analysis can be applied to other tools to better evaluate metrology. The converse method is useful to determine a process' variance and bias -vital information to evaluate and compensate a facility, process, or device.

As oil fields approach maturity, unwanted water production often starts negatively affecting oil recovery. Under these circumstances, operators may extend the well's useful life by plugging and abandoning (P&A) underperforming intervals and perforating a new formation. In Ecuador, this workflow is traditionally completed with wireline or tubing-conveyed perforating. An alternative method using enhanced coiled tubing (CT) is presented here; it enables a rigless and efficient workflow that leverages real-time downhole data for on-the-fly optimization. The new workflow relies on CT-conveyed technologies without requiring any additional conveyance methods. CT delivered four different services to initiate the abandonment by anchoring a 7-in. cast-iron bridge plug, complete the abandonment with a low-viscosity cement plug, simulate wellbore dynamics during nitrogen pumping to generate the required underbalance conditions for perforating, and perforate with a 40-ft ballistic payload of 4 1/2-in. guns. Coupled with real-time downhole telemetry, the enhanced CT workflow provided critical downhole conditions, including fluid levels, accurate depth placement and control, bridge plug setting confirmation, underbalance conditions, perforating head activation and detonation, and post-perforation inflow monitoring. Compared with traditional methods, the workflow with enhanced CT introduces several benefits toward completing P&A of old intervals and perforation of new ones. These benefits include enabling a rigless workover, eliminating the need and cost of a workover rig, reducing operational duration by 13%, and potentially reducing asset footprint and field crews by 95% and 70%, respectively. Elimination of a workover rig reduces environmental impact and the number of personnel on location (i.e., risk). The workflow also extends both reach and efficiency of the service in horizontal wells, enables underbalanced perforation, and delivers actionable real-time downhole data. These data elevate traditional P&A workflows and create a step change in efficiency. First, they allow tracking key downhole parameters that help guarantee a reliable operation of each of the tools and services. Second, they shed insights as to the actual downhole conditions throughout the intervention to enable the operator and the field crews to make on-the-fly decisions to deliver a safe and optimal service. Those decisions may include fine-tuning the prescribed treatment or extending the scope of the intervention by leveraging the CT's pump-through capabilities to maximize well performance and meet, or exceed, the operator's objectives. The innovative combination of real-time telemetry with abandonment and perforating technologies proved a step change in operational efficiency and range, fueled by the quantity and quality of data recoded during the operation. This case study also marks the first documented perforation with 4 1/2-in. guns with fiber optic real-time downhole telemetry. Furthermore, the integrated, rigless solution provides operators with an opportunity to extend their workover activity pipeline and free up their workover fleet for other activities.

An innovative coiled tubing (CT) real-time flow measurement tool was introduced in Ecuador to reformulate the stimulation workflow in water injectors, which comprised evaluation and treatment. This new technology enabled an integrated, single-run workflow instead: initial injectivity measurements, diagnostics, treatment, post-stimulation injectivity measurements, and final diagnostics. This novel, rigless approach reduced equipment footprint, operational time, and cost, and it improved production as compared to the conventional approach, despite accrued capital discipline constraints. Conventionally, operators rely on workover rigs and multiple product lines to diagnose, stimulate, and evaluate injector wells. Several challenges and inefficiencies were addressed by deploying the CT real-time flow measurement tool. Each intervention was designed to be completed with a single CT run, and without the need for a workover rig, thus saving costs and time. Tailored diversion methods substituted the need for drillpipe to set mechanical packers. Prestimulation injection logging test (ILT) results obtained with that innovative tool, coupled with real-time control of depth and high-pressure jetting during execution, enabled effective placement of the stimulation treatment. Ultimately, post-treatment ILTs confirmed treatment effectiveness and final wellbore downhole conditions. Introduction of the CT real-time downhole flow measurement tool allowed operational objectives to be met in a single run, without additional interventions, with or without a workover rig on site. When workover rigs were present, this improved workflow saved an average of 15% operational time. In cases without a workover rig, 105 hours of rig time were saved (without considering rig mobilization time). Four case studies are presented. The first two cases demonstrate how acquisition of ILTs throughout the intervention enabled optimization of fluid placement and introduction of diverter methods. The third case covers a scenario where there was an initially low injectivity and highlights the challenges and lessons associated with recovering injectivity. The fourth case presents challenges unique to flowmeter measurements in heavy-oil environments. In each case, effectiveness of the optimized treatment was measured by two metrics: improvements in net injectivity and uniformity of injection profile, both of which drive the effectiveness of secondary recovery in connected producer wells. On average, wells intervened with this approach featured an improvement in injectivity of 301% (compare to 226% conventionally) and in their injection profile homogeneity by 13%. As a result, the productivity in connected wells improved by as much as 74%, and an average of 39% (compared to 14% conventionally). This innovative workflow is a step-change over conventional approaches to rejuvenate waterflooding. It combines the capabilities of delivering treatments via CT and the power of real-time downhole flow measurements to break the paradigm of multi-line, multi-run operations to remediate and stimulate injector wells. This yields logistically leaner operations, which are less costly, and it enables breakthroughs in secondary recovery through data-enriched interventions in times of budget pressure, not only in Ecuador, but also across the globe.