The strategies focused on solving the issues of a mature field should consider the declining production in order to stablish future investments, to not fall into costs that could reduce competitiveness and in the worst case reduce profit. The Block 49 (B49) is an oil field with almost 50 year of exploitation with typical mature field related problems as low productivity, reservoir depletion, high rate of water production which requires of a group of mechanism to become a competitive field in the current market conditions. The optimization of the recovery factor and the implementation of an energy efficiency model were the axes to reduce the OPEX and reach a barrel with a production cost of 5.20 USD. The main goal of waterflooding in B49 field is maximizing oil recovery while minimizing water production, in this case, the injected water for the secondary recovery is the formation water from the north and south zones of B49. As consequence, the recovery factor increased from 21% to 26%. For many years in Ecuador, the gas as consider as a waste sub product, for this reason the gas flaring was an accepted practice, however, since 2009 Ecuador’s national oil company, has been executing an ambitious Energy Efficiency Program. This Program, also known as Optimization of Electricity Generation and Energy Efficiency (OGE&EE), is a comprehensive development on generation, distribution and transmission of electricity, as well as the development of facilities for the capture and transportation of Associated Gas (AG). The Program consists of a cluster of projects in an area covering 25,000 sq. km., 17 oil blocks, 56 oil fields and more than 66 facilities. The results of this Program can be summarized as following: Multiple power plants with a combined power of 325 MW, 95 MW of these power plants can use associated gas as fuel.More than 200 km of power transmission and distribution facilities to deliver power based on economic and environmental merits; and,Approximately 17 km of gas gathering and transportation facilities of a total scope of 100 km, bringing deteriorated facilities up to standard and implementing waste heat recovery systems.The OGE&EE Program also had interconnected the oil industry electric grid to the national grid, which helps to optimize national renewable energy (hydropower). In 2015 Ecuador’s national oil company joined the World Bank’s initiative "Zero Routine Flaring by 2030", the Government of Ecuador also joined this initiative on 2018, and as part of Ecuador’s national oil company energy efficiency program, since 2015 it has been working to develop project and financial solutions to increase more Associated Gas Power Generation and to gather Associated Gas from lower scale flares. This approach uses gas production at the well before any flaring, the B49 field uses the production of 12 wells for electricity generation, the average daily demand is 3MW (72MWH each day). The electric generation of B49 meet the targets of efficiency since it uses gas of low-calorific value in high efficiency generator sets, 100% of the energy need of the field is generated, 16MMcf of sweet gas is used monthly, stops the emission of 533 Ton CO2 eq/KWH, and results in 562 M USD of savings due to not diesel consumption. Problems as CO2 emission reduction, gas availability, gas flaring limitations, facilities to maintain the pressure, gas transportation (processing-distribution), depletion of the reservoir, water injection, and increasing of the BSW are issues addressed in this research.

We discuss the application of overflushing along with pillar fracturing in a mature oilfield in Ecuador, where an effective high conductivity (high proppant concentration) fracture is required to enhance productivity because of low reservoir pressure and high permeability. Hydraulic fracturing is a proven technology used in the Oriente Basin with three challenges that remain constant (1) maximize conductivity and (2) reduce proppant flowback risk in the production stage and (3) reduce well intervention time. To address these challenges a combination of overflushed pillar fracturing, and tip screen out (TSO) are proposed. We show the reservoir analysis, laboratory tests and hydraulic fracture modeling performed to support the implementation of overflushing. Reservoir analysis includes a methodology used to execute an optimized fracture design, and laboratory tests include core flow tests that define non-damaging fluids to be used during workover and fracturing operations, and relative permeability modifiers (RPM) for water conformance. Relevant results are also presented using three key performance indicators (KPI) to evaluate the effectiveness of resin-based pillar fracturing with overflushing viz., (1) pressure buildup data (2) fluid production and (3) productivity index increase post fracturing. Three case studies are presented for fracturing candidates with special conditions, that show that this technique can be extended beyond the traditional job. Pillar fracturing (fracture and refracturing jobs) combined with overflushing in conventional reservoirs is documented for the first time, with effective stimulation results. This study applies overflushing, a practice developed for completion efficiency in unconventional reservoirs, and combines it with already proven practices in mature conventional reservoirs (pillar fracturing, customized fluids, 3D fracture design, and water conformance while fracturing) with a positive effect on production enhancement and proppant flowback risk reduction. Pressure buildup tests confirm no adverse effect of overflushing since negative skin or bilinear flow is observed, along with an increase in fluid production and productivity index in the studied wells.

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El presente documento muestra la realidad, desafíos y perspectivas de recuperación secundaria del reservorio “U Inferior” (UI) en el campo Sacha, localizado al flanco occidental del “Play Central” (Corredor Sacha-Shushufindi) del oriente ecuatoriano. El histórico de producción inició en el año 1972 con perforación de pozos, y años después, con proyectos de recuperación secundaria, se logró el incremento de la producción petrolera. La arenisca UI es uno de los principales reservorios productores del campo, se destaca por su alto volumen de reservas 3P y la presente oportunidad de recuperarlo a mediano plazo sin ser este el único reservorio productor con recuperación secundaria. La realidad del campo muestra que las intervenciones a las zonas productoras y la aplicación de técnicas de optimización de producción como fracturamiento hidráulico, producción commingled, estimulación matricial, cambio de zonas, perforación, entre otras, se han visto limitadas por las bajas presiones en los reservorios de la formación Napo; los cuales se encuentran depletados y con presencia de gas libre. Por ello, se generan retos adicionales en diferentes escenarios evaluados de incrementos de producción, para el manejo de los fluidos y sistemas de levantamiento artificial tradicionales. El desafío es buscar el desarrollo del campo bajo estas condiciones, mediante simulación, aplicando el método de Buckley-Leveret e implementando proyectos adicionales para recuperar la presión de la arenisca UI definiendo arreglos de inyección y repotenciación de facilidades existentes (actualmente limitadas), logrando así exponer los casos ideales ajustados a la realidad y mostrar el aumento de volumen de producción acumulada del campo bajo ciertas perspectivas a favor de los intereses del país.

This study describes different laboratory tests used to identify formation damage mechanisms associated in the Hollín sandstone. Traditionally Hollin sandstone is divided into two zones: Lower Hollin or Main Hollin and Upper Hollin, each one with unique characteristics as well as formation damage mechanisms. Laboratory experiments for fluid customization (salinity sensitivity, completion brine sensitivity, regained permeability and relative permeability modifiers (RPM)) are performed to support the different techniques applicable to each reservoir. Acid stimulation was proposed as the main stimulation technique since core flow tests demonstrate improvements up to 400%. Aditional treatments were tested to increase time between interventions such as fines stabilization blends and effective stimulation near water zones (RPM) or as chemical diverters. A workflow for ranked candidate selection is describedwhich includes well, reservoir and mineralogy information available to categorize possible formation damage mechanisms as well as to recommended treatment type, volume and expected productivity post stimulation. Job results from 2016 to August 2021 are included to support the overall investigation. Finally, additional treatment combinations are proposed to improve productivity and to extend the productive life of the well.