Solid Fast-Track Evaluation Methodology: Supporting the Decision-Making Process in the Development of Mature Assets

Abstract

As most oilfields in Ecuador are approaching to the end of the service contracts under an advanced degree of maturity, it was imperative to implement a fast-track integrated methodology that supports the decisionmaking process during assets' evaluation. This practice aimed to identify new business opportunities and assure the rehabilitation of brownfields. These fields became a target for investors willing to intervene in new joint ventures with moderate risk to boost production and returns. The methodology is prepared to overcome specific challenges such as severe reservoir pressure depletion, harsh water management issues, facilities constraints and integrity. All this while keeping economics and safe operational standards. This process is divided into five stages: First, the diagnosis of field challenges and associated risks, so that review the current status of subsurface and surface aspects. Then, the following three parallel phases are focused on the study of reservoir architecture, dynamics and performance. Finally, the remaining potential of the asset is assessed by integrating action plans to take advantage of current facilities capacities. This workflow was implemented for the evaluation of three assets: Asset 1: Mature field with a secondary gas cap where its current reservoir pressure is 800 psia (initial pressure 4,200 psia). The asset was evaluated in fifteen (15) days resulting in an integrated solution with 14 activities: conversions to injectors, water source, upsizing, reactivations, change zone, and new wells. The results presented an incremental recovery factor of 6% (by 2028) with an expected production peak of 3,500 BOPD (by 2021). Asset 2: A field producing from two main reservoirs with harsh water management issues under a non-monitored waterflooding scheme with challenging sweet spots identification was evaluated in 10 days, resulting in a redevelopment plan considering: production losses optimization, sixteen (16) activities: workovers, dual completions, new wells, reentry, shut-in, and conversion to water injectors. This evaluation delivered an incremental recovery factor of 10% (by 2029). Asset 3: Producing for around one-hundred (100) years with 3,000 wells drilled. There was a lack of pressure support and facilities and well completions integrity. The fast-track assessment focused on production optimization lasted fifteen (15) days, resulting in one-hundred eighteen (118) wells for reactivation representing an additional recovery factor of 3% (by 2029). This work supported the process for contract's renegotiation and assets' acquisition. This integrated methodology aimed to maximize the assets' value while considering the involved shareholders' needs. Each asset was analysed in an integrated and collaborative manner through the propper resources identification and the usage of the latest technology and workflows. High-resolution reservoir simulation, complex python scripts, and a chemical processes simulator were used to perform an in-depth evaluation and meet the expectations.