A Reversed Geo–Dynamic Approach for Brownfield Rejuvenation

Abstract

Summary Brownfields in this paper are defined as mature fields where production declined to less than 35–40% of the plateau rate and where primary and secondary reserves have been largely depleted. Big data, high field complexity after a long production history, and slim economic margins are typical brownfield challenges. In the exploration-and-production (E&P) industry, “sequential” field-evaluation approaches (first “static,” then “dynamic”), have proved successful for greenfield development, but often do not achieve satisfying results for brownfields. This paper presents a new work flow for brownfield re-evaluation and rejuvenation. The “reversed” geo-dynamic field modeling (GDFM) rearranges existing elements of reservoir evaluation to obtain a purpose-driven, deterministic reservoir model, which can be quickly translated into development scenarios. The GDFM work flow is novel because (1) it turns upside down the discipline-driven sequential work flow (i.e., starts with the history match) and (2) it uses dynamic data as input to calibrate seismic (re-) interpretation that acts as a main integration step. It combines all available data already during horizon and fault mapping. Field diagnosis, flow-unit identification, well-test reanalysis, and petrophysical and geological interpretations are all combined in a cross-discipline interaction to guarantee data consistency. This directly ensures a fully integrated, “geo-dynamic” model that forms the basis for reservoir modeling. The full dynamic/static data coupling at an early stage is the main strength of the GDFM. It reduces the model complexity, and narrows the uncertainties. Project-execution time is considerably shortened by avoidance of the characteristic full-cycle loop iterations of the sequential approaches. A brownfield example illustrates the benefits of GDFM: a consistent history match with high model accuracy and confidence. In the field example, the GDFM work flow has facilitated a turnover at only 70% of the original time budget. The ongoing drilling has confirmed model validity (“attic oil” predictions), thus further postponing the economic limit of the brownfield.