AAPG Middle East Region Geoscience Technology Workshop

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Geomechanical Variability within Siliciclastic Reservoirs of Oman

Abstract

Depositional settings and diagenesis of the siliciclastic reservoirs in Oman have noticeable implications in their geomechanical properties and behavior. Highly varying depositional environments and paleo-tectonic regimes in the three basins not only affect the reservoir quality but also rock mechanical response to the development. The latter in its turn dictates the choice of engineering solutions. Additional levels of complexity are provided by salt bodies’ distribution in the basins, substantial property variability with depth within similar lithologies, and structural and in-situ stress controls in some areas. As a result, a geomechanicist faces multiple challenges when it comes to rock mechanics characterization and modeling. Some of those challenges are unreliability of laboratory measurements and of certain types of logs. In many cases the characterization becomes more qualitative than quantitative posing limitations on deterministic modeling and raising a demand in statistical / probabilistic treatment. Thus, understanding regional geological context becomes pivotal for planning the operations in green fields in particular. This talk will consider a series of illustrative examples of the links between the geological settings and geomechanical behavior of the rocks. The examples will include the discussion of links between well completions / production technology and i) the depositional environment / burial history and petrophysical / geomechanical properties, in the South Oman Basin; ii) reservoir architecture and hydrofracture behavior in the Ghaba Basin; iii) salt presence / removal in the Ghaba Basin; and iv) tectonic regime in the Fahud Basin.