Impact of CO2 corrosion on well integrity is an issue in mature fields of Colombian foothill wells. Concerns in regard to corrosion of casing strings having access only through the existing 7" completion challenged the use of new technology to achieve both: log corrosion on outer strings and do not suspend the well to get a full column of fluid. Therefore, corrosion monitoring was performed through 7" chrome production tubing with a new Electromagnetic Scanning Tool (EMST), in a challenging scenario: shut-in well with 3 outer casing strings with a gas cap in the upper wellbore. The job objectives were first to test the technology to detect metal loss from the outer casing strings as well as loss both inside and outside of production tubing (without pulling the production tubing) and second to establish a base line for future corrosion analysis after the immediate drilling rig intervention for sidetracking. A careful candidate selection was performed based on criticality for CO2 corrosion, completion design, service years and operating status of the well including consequence analysis to get a pilot well for EM logging. In production since 1998, the BA Y16 well was selected to be logged before a thru tubing deepening to reach two other reservoirs and further service conversion from oil producer into a gas injector well; the EMST was run in Q1 2013 and measuring the cumulative thickness up to three strings determining that no external corrosion was present in particular in the section of interest, also the high resolution image showed no presence of internal corrosion. Therefore, a successful operation was achieved meeting the proposed objectives with no HSE incidents and within budget. This technology is proven and has become a solution for further wells where CO2 or bacteria damage has been evidenced including corrosion mapping through chromed and carbon steel in a single run avoiding the excessive costs related to pulling the completion to get access to the outer casing strings.

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Schlumberger implemented the first instrumented platform integrating advanced measurements in real-time while perforating with plug-in gun connections. This paper presents the results obtained at field level using this technology in Ecuador and a comparison of this technology with perforating operations and techniques in terms of efficiency, reliability, and correlation between the predicted and measured dynamic events to perform a full evaluation of the perforating design process, execution and its impact in well performance Out of more than 120 jobs performed year to date in Ecuador, the authors selected 5 wells covering operations with dynamic underbalance (simultaneous and standalone) and gas fracturing to illustrate the efficiency gains of a faster and more reliable arming system and to analyze the match between simulated and measured dynamic events (pressure and shock). Among the 5 wells, two of them achieved positive production results, and the real time measurements showed additional information in terms of: reservoir pressure, well response, and perforations cleanup during the job execution. The other three wells provided key information related to well control and pressure buildup after perforations, withal they did not provide comparatively consolidated production results.

Managing sand production is critical in brownfield operation. Solid productions are often causing issues with completion and surface facilities. Sand management and prevention are the current practices and leaving sand control as the last option if required. To make better informed decision to select sand control, one must understand, managing and preventing two conditions that may cause sand production: formation failure and sand transportation which lead to this study. The integrated approach started from technical screening of available sand control methods, followed by statistical and Monte Carlo process, geomechanics analysis, dual packer formation tester, identification of sand production prone layers, perforation system optimization and pilot wells evaluation. Technical feasibility of sand management and prevention was evaluated using Bayesian knowledge engine and extensive historical case based reasoning. All the producers with sand problems were selected for a statistical analysis to correlate the production characteristics with sand production behaviours. Significant correlation was observed for the velocity per perforation with the severity of sand production trend. Sand production is less with reduction in the velocity per perforation.The velocity threshold limit was identified using a dual packer formation tester. Utilizing Monte Carlo probabilistic analysis and considering the variation in reservoir properties, the probable threshold limits were identified for different reservoir within the same field and area. Combining these limits with previous statistical analysis results, for this field those wells that producing higher than the medium limit historically quadruples in the sand production.In order to address the heterogeneity of the reservoir, a sand production prediction log was created. This log combines the mechanical earth model, geology and velocity at each perforation versus velocity threshold limit for sand transportation. This gives a complete integrated insight understanding of sand production across each perforation interval. Briefly, the log will indicate if there is possibility of sand production. The log was tested with the existing wells. Sand production was observed at surface exactly as the log interpretation. The optimum perforation system was evaluated using one of the commercialized software. The selection criteria and constraint were strongly governed by the mechanical earth model, mud invasion analysis, well productivity, sand transportation velocity threshold limit, decision risk analysis and economic evaluations. All perforation systems velocity profiles were evaluated with sand production prediction log mentioned earlier. This aid tool enables layer by layer perforation system optimization to manage potential sand production problem and guideline for production optimization processes. This paper discusses integrated approach for sand management prevention. Case study shows 2 pilots were selected for this project using the above mentioned approached. The results are favour...

Casabe Field is a heavy crude mature field with 260 producers, under selective injection of water with 350 injectors, producing close to 14,000 bbl/d of oil and about 80,000 bbl/d of water are being selectively injected under a 5-spot injection model. High water injection rates develop as consequence high flow velocities along its high permeability thinned sands, causing sand jetting over the cement and casing and seriously affecting the integrity of the well and zonal isolation. As typical in a brown field, operational costs are close to the limit, and sand cleaning represents almost 90% of workover operations with an average of 3.4 sand cleaning interventions per year in evaluated wells, which means an inoperability of 40% of time per year. Those events have represented millions of dollars in well interventions, abandonments, and water treatment, for which an aggressive sand management strategy was designed to optimize field operation. This strategy consists of identifying producing intervals with evidence of sand production in wells with high failure rates, in order to take effective and efficient corrective actions to recover the normal operation of the well with an optimized production. The identification of potential sand-producer intervals has been performed with the combination of last generation of cement evaluation with porosity wireline tools, applying a novel analysis of the acquired data through the processing of a flexural wave to characterize the geometry of the third interface (or open hole). Characterizing the annular geometry with mentioned technologies, has helped identify indications of cavern development behind the casing which also correlates with casing deformation, corrosion, and cement degradation, something expected at sand-jetted intervals. This, of course, means not only production loss but also integrity loss that threatens nearby zonal isolation. In all the cases where caverns have been detected, cement was strategically and efficiently pumped to cover formation washout. Post-workover and production reports indicate continued production was reached as inoperative time was reduced from 40% to 10%, but also well intervention for sand clean out was reduced from 3.4 to 1.4 per year on evaluated wells. This sand management strategy has been conducted in 10 wells in which more than USD 9 million cost-saving in workover activities have been reported. The application of new technologies and new ways of data analysis to inspect the physical condition of downhole barriers enabled the operator to save costs and to maintain the control of the integrity of the wells in aggressive environments such as the existing in Casabe Field. The experience gained in the process of identifying caverns behind the casing can be easily passed to other engineering teams facing similar situations, for example in neighboring fields of the Medium Magdalena Valley of Colombia.