A novel workflow was developed to select the optimal field development plan (FDP) accounting for the associated uncertainties in a green onshore oil field with a limited number of wells and no production data. The FDP was then revisited in view of the performance of wells drilled during the execution phase and updated as needed based on the acquired data . Comprehensive uncertainty analysis was performed resulting in multiple subsurface realizations. A broad set of development scenarios and options were screened under uncertainty. The viable scenarios were then economically evaluated, resulting in an optimal FDP that is robust to uncertainty and the least risk prone from an economical point of view. The used workflow was specifically suitable to test many development concepts and explore various options including horizontal well orientation, well pattern concept, pattern acreage and spacing, length of the horizontal sections, and landing of the horizontal sections. Following an extensive techno-economic analysis of all possible combinations (900 in total), the most robust development concept was selected and analyzed considering the viable development strategies pertaining to plateau rate, drilling schedule, phasing, water injection timing and artificial lift timings. A phased development approach was adopted enabling acquiring necessary data to mitigate the remaining uncertainty and avoid costly consequences of significant over- or under-capacity. Data acquired in one development phase were assessed and used to update the following planned phases, if necessary. The study demonstrated that the field development could accommodate a delay in either water injection or artificial lift implementation. Although it was not recommended at this stage to delay either of them, it is noteworthy that the long lead time that may be incurred in the implementation of artificial lift or the risk of lower injectivity would not impact the field performance or ultimate recovery if contained to a few years during initial production. These results further reinforced the robustness of the proposed development plan. Large subsurface uncertainty combined with an extensive set of possible development scenarios and options required cutting-edge uncertainty analysis and screening workflows to select the optimal FDP. These unique workflows can be readily used in similar green fields to help arrive at the final FDP.

Early assessment of enhanced oil recovery (EOR) potential in fields that are at early development stages is becoming more common in the oil industry, ensuring that investment decisions are consistent with the EOR deployment once the field reaches maturity. Well, facilities and monitoring design maybe influenced to accommodate the EOR implementation, thus reducing Capex and mitigating project exposure. Challenges arise, as expected, due to the limited information, particularly when the field has not yet been under production and dynamic information of connectivity, compartmentalization and reservoir extend is scarce. This paper describes the screening analysis performed on an onshore marginal green field in the UAE with four drilled wells and no production history with water injection considered on the approved development plan. The comprehensive screening workflow resulted on a narrow list of potential applicable EOR methods and their corresponding benefits allowing the operator to tailor development activities for early EOR de-risking and accelerated field deployment. A multi-dimensional approach was adopted using a combination of numerical, analytical methods and past EOR experience, to shortlist and rank the most attractive EOR development options, robustness of the selection (and ranking) was tested under the key reservoir uncertainties. WAG was identified as one of the better suited EOR processes (complemented the planned waterflood) along with miscible CO2 injection (with possible WAG applications).