The Auca field, located in the Amazonian region of Ecuador, started production in 1970, reaching a peak of 75,000 BOPD in March 2015. By the end of 2015, production declined to 65,000 BOPD due to water cut increase, reservoir pressure loss, and progressive formation damage. In January 2016, Petroamazonas EP (PAM) and Schlumberger (SLB) initiated the Shaya Project with the objective of increasing production and reserves through infill drilling, secondary recovery, and well interventions. The Auca field produces from the Hollín Formation and the Napo U and T sandstones. The latter two normally suffer from pressure depletion due to weak aquifer support, whereas the Hollín formation maintains reservoir pressure due a strong aquifer acting from the bottom. In general, formation damage in the Auca field is caused during drilling and pulling activities due to invasion of drilling or control fluids, but it also happens naturally in form of scale precipitation which has been physically proved, and possibly fines migration which remains a theory yet to be verified. Several workflows, procedures, and research on the nature of the damage have been put in place to resolve the production loss and decline issues associated with the varios potential causes. The selection of the most appropriate damage-removal technique depends on the reservoir and fluid properties, reservoir architecture, production behavior, water diagnosics, well intervention history, well geometry, artificial lift system, and, most importantly, the nature of the formation damage. From the reservoir and production engineering perspective, understanding formation damage and identifying its root cause is a key for designing the appropriate solution. After 18 months of intensive activity with drilling and workover operations, the production of the Auca field is close to 72,000 BOPD. If the operator had decided to stop activities, the production baseline would be at 35,000 BOPD. This means that, at present, the project has contributed a net incremental of 37,000 BOPD, of which approximately 30% corresponds to damage-removal jobs. This is a case study on one of the largest producing oilfields in the Oriente Basin that shows the typical productivity issues to deal with siliciclastic reservoirs and provides an example of how to select the most appropriate damage-removal techniques.

A new Integrated Exploitation strategy to boost production and incorporate reserves at the Ecuadorian Bloque 61 was put on the table to radically change the production strategy from primary to secondary recovery in only two years timeframe. This was accomplished by drilling appraisal, development and infill wells in conjunction with peripherical and pattern waterflooding. The project departed from reservoir characterization and modeling to identify the potential targets for waterflooding. The identified opportunities were assessed and ranked. Consequently, several pilots were implemented as a proof of concept. Once the waterflooding pilots were in place, the complexity of the reservoir was evaluated. To account for the subsurface uncertainties, a probabilistic approach was followed to do the economical evaluation and risk management for the expansion. Novel facilities configuration, implementation of new completion design and production enhacement techniques, along with a robust surveillance plan played a key role for the rapid implementation of a new exploitation strategy. Positive reservoir pressure response and incremental production were observed within one to three months right after injection started in the pilots. This behavior was similar for the other fields where waterflooding was expanded. As such, new wells drilled and well reactivations in areas influenced by waterflooding has proven to have a threefold increase in expected initial productivity, therefore, the increase of reservoir pressure opened new development opportunities in Block 61 in former depleted reservoirs. The implementation of a new exploitation philosophy focused in secondary recovery, increased recovery factor in about 10%, the contribution from waterflooding is about 30% of the total oil production. Additionally, 50% of the volume to be developed, corresponds to activity to be completed in Waterflooding areas. This waterflooding strategy represents a shift in the exploitation paradigm in the Ecuadorian E&P industry, by going beyond the pilot execution through proper risk and uncertainty management as a path to full-field implementation. To fast-track this deployment of the water injection, a closed loop system was implemented between the water source and the injector to reduce facilities costs up to 80% as no treatment is required for the injected water.

An Ecuadorian lease ("Bloque 61") composed of 14 oil fields represents the most productive asset in the country. It contains 5.3 billion barrels of original oil in place (OOIP) distributed in four complex producing reservoirs. After 44 years of production and with a decline rate of 31% per year, maintaining the production from these fields represents an important challenge from the subsurface and execution viewpoints. In December 2015, an integrated service contract was signed with the national oil company (NOC) with a fixed investment for the development of the entire lease. The challenge of the project was to maximize the value of a depleted asset through the framework of the contract. This mature asset has many opportunities to boost production and reserves by implementing an aggressive fit-for purpose development. The opportunities screened and implemented in only 12 months consisted of reaching new oil in appraisal and exploration areas and redevelopment of mature zones with horizontal and infill drilling with mainly reentry wells. Most valuable of all was the implementation of six waterflooding projects. All of these were executed in the Amazon rainforest where there is a pressing need to reduce environmental and social impact. This exploitation philosophy has successfully changed the asset’s production decline, ramping production up from 60,000 BOPD to 80,000 BOPD. This integrated field development plan has amalgamated several technologies with a specific objective of optimizing the value of the asset. The long term was assessed through the drilling of exploration and appraisal opportunities where prospective resources were recategorized to reserves. The medium term was tackled by drilling horizontal wells and re-entries to optimize sweep efficiency and implementing water injection in the main structures. The short term was directed by executing workovers in areas where the water injection was in place. The asset value was recovered and increased as shown by a reserve’s replacement ratio of 1.13. This approach will serve as a framework for the future integrated development of these types of mature assets. The technologies implemented have helped accelerating and optimizing the conceptualization and execution of the project; a few of these include high-resolution reservoir simulation, dumpflooding, closed-loop water source system, and dual-string completions. The integration of strong domain expertise, coupled with advanced technologies and workflows, has led to outstanding results.