Formation Evaluation for Thin Bed Shaly Sand Reservoirs

摘要

When developing oil and gas fields, there are often the reservoirs consisting of alternating thin sedimentary thin layers of various rocks, clays, siltstone and sandstone (Fig. 1). Current low oil prices driving reexploration of mature fields and, therefore, the interest in interpretation of such non-standard, thin and/ or low resistivity and low resistivity contrast formations is increasing. Over time, they ceased to be simply a phenomenon and turned into objects of careful attention. The vertical thickness of these layers varies from a few millimeters to several centimeters. Such deposits are widespread on the territory of Russia (Volga-Urals, Timan-Pechora, West Siberian and East Siberian oil and gas provinces, Pre-Caucasian region, Sakhalin, etc). Thin-bedded Reservoirs are a promising oil and gas objects, but quantification of individual petrophysical properties of thin layers, such as porosity and saturation, with standard set of logging and standard methods of interpretation involve considerable complexity. In case of thin-laminated reservoirs logging data are the averaged characteristics of interlayers of sandstones and clays, with a thickness less than the vertical resolution of standard logs. In this regard, traditional approaches to data interpretation in thinly bedded reservoirs do not allow to reliably estimate their reservoir properties to determine the volumetric parameters for the subsequent estimation of hydrocarbon reserves or even just for involvement in the development of hydrocarbons.