In Argentina, over the last decade mature field management has been of paramount importance in ensuring economic sustainability for many oil field operators. Success requires solving a specific suite of problems comprising mixed generations of technology (in particular logging tools), long and complex well histories and often the sheer size of the dataset. The field in this case study has been in production since 1964 reaching its maximum production capacity of 32000 bpd during 1969, after which decline began. Consequent depletion from 140kg/cm2 to 20kg/cm2 drove the need for pressure support that was achieved through waterflooding which was implemented in two major campaigns during the 70's and the 80's. A total of 354 wells comprise the historical dataset with recent re-drills, extensions and infills bringing the total well count to 422. Re-evaluation of the remaining target via a series of studies carried out between 2006 and 2009 indicated an attractive opportunity for 7 spot waterflooding and saw the commencement of a massive re-development of the field. Behaviour of recent wells has been worse than predicted. This deviation from expectation initiated a series of studies to better characterize the reservoir with the objective of re-defining targets for incremental development. Associated with these studies new geological and dynamic models were built using re-evaluated historical data integrated with information from 68 new wells and 8 new cores. In particular, the impact of textural variation and thin bed architecture on the meso-scale oil distribution was assessed allied with a range of different techniques to identify macro-scale compartmentalization. The result was an integrated model that enabled comprehensive re-evaluation of the remaining targets. The approach used in this study to identify and characterize thin beds in this type of setting, define the impact on OOIP and determine the remaining oil in place in order to evaluate opportunities can assist many operators who experience various challenges associated with developing mature acreage.

The interplay among reservoir heterogeneities, structural complexities and unfavorable mobility ratios are usually responsible for premature water breakthrough in brown fields across the world. Recently, a deep conformance control technology, known as Thermally Activated Particle (TAP), has been successful in addressing this challenge. Limited intervention and lower deployment cost make it very attractive for mature waterflooded fields. Cerro Dragón is a giant field located in San Jorge Gulf basin with multi-layered channel deposits. Presence of highly conductive channels and unfavorable mobility ratios have severely impacted the sweep efficiency, resulting in low oil recovery and high water production. Building on the learnings from the previous pilots, TAP has been recently deployed at a segment scale in one of the blocks of Cerro Dragón field. This paper shares the technical details behind the screening, designing and the deployment of TAP technology. After initial screening of multiple candidates, a reservoir segment has been selected for TAP implementation. Inter well tracer data with comprehensive injection/production data analysis identified the communicating wells and thief zones volumes were then estimated around each injector. The estimated thief zones volumes were also confirmed by volumetric calculation. Thermal modeling and numerical simulation were utilized using a representative and history matched model to finalize the size, concentration and the proper activation of injected TAP molecules. Subsequently, in early 2018, nearly 360 metric tons of TAP was safely deployed into six target injectors. This campaign met all design guidelines, all planned surveillance data was acquired, and the project was executed on time and on budget. Post deployment, frequent sampling at offset producers was performed confirming no breakthrough of un-activated polymeric particles. Oil rates and WOR trends are currently being monitored, as part of the longer-term surveillance plan, to quantify incremental benefits from TAP EOR technology. Previous 2011 implementation and positive results in other segments of the field were an important input and they are also described in this paper. The results of this treatment will provide very helpful guidelines that can be used in any brown fields to improve the efficiency of waterflooding especially in highly heterogeneous reservoirs with low waterflooding performance.