The influence of geological model resolution on the history matching by the example of the East-Messoyakhskoe field

Introduction. This paper considers the issues of history matching process based on different conceptual geological reservoir models of the East-Messoyakhskoe field. The specific feature of considered deposits, associated with Srednemessoyakhskiy swell (graben area) is high well spacing density, and therefore, the different realizations of geological models are comparable with each other when using different modeling algorithms/approaches. The assessment of gas reserves in the gas cap based on well operation process differs significantly from the reserves in the geological model (in all realizations). The problem is complicated by small number of hydrodynamic studies.

Aim. It is necessary to improve the geological model relying on well log and production data sets.

Materials and methods. The history matching process is presented in iterative way. The iterative approach is based on the analysis of well sections, paleo-thickness maps, seismic attributes, facies analysis.

Results. The presence of lateral barriers (tectonic and lithological factors) was identified based on reservoir simulation results. The geological sections of the studied deposits associated with Early Cretaceous age (berriasian-valanginian) is represented not just by a series of bedding layers, but by an alteration of bodies of various scales, extensions with different poro-perm properties. The sand bodies can be differentiated by shale layers or layers with low net to gross ratio — so these zones will be disconnected. Based on the conducted research, the following studies were recommended: gas cap energy state monitoring using piezometric wells, pressure build up logging, reservoir pressure determination, performing pressure interference test.

Conclusion. With high well spacing density the different realizations of geological models are comparable with each other. However, despite of high degree of geological and geophysical knowledge, the history matching results indicate a more complex geological structure. This is a reason for revising the geological settings. There are disconnected zones that are partially visible on seismic data, but they can be confirmed by well testing data, reservoir energy state, different levels of gas-oil-water contacts and caused by sedimentary environment.

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