ESTIMATION OF PERMEABILITY ANISOTROPY CALCULATION QUALITY ON THE EXAMPLE OF A TERRIGENOUS FORMATION

Abstract

The relevance of the research. The oil industry is developing through practical subsoil use. As Aleksey Emilievich Kontorovich and co-authors note in the program and concept for the development of the oil and gas industry in the Tomsk region for 2001–2005 and the period up to 2030 – the current structure of forecast oil resources in the main oil and gas producing regions of Russia, including the Tomsk region, is such that in the coming years, mainly small in terms of reserves and a small number of medium and large fields will be discovered. For the development of small and medium-sized deposits, it is necessary to create prerequisites that stimulate the widespread involvement of a large number of enterprises in subsoil use. The proposed technology just meets all the requirements. And, most importantly, a high-quality result is achieved by additional calculations of primary a priori information. The aim of this work is to investigate the intercoal strata of the studied field for the presence of permeability anisotropy; determine the anisotropy parameters using the already implemented technique on the overlying and underlying layers of this field; prepare data for further geological and simulation modeling. The study object is the intercoal strata of the Upper Jurassic terrigenous formation. The deposit is located within Western Siberia. A preliminary study of geological and geophysical information allows, with a high degree of probability, calculating the heterogeneous distribution of reservoir properties. Methods: creation of a petrophysical model. It must meet the quality requirements and reliably characterize the properties of the core. Later, the porosity and permeability are calculated for the intervals of the target formation drilled by the wells. The distribution of properties over an area creates a permeability map. This map is further analyzed using vector and gradient analysis views. The result is datasets of magnitude and direction of permeability anisotropy. The main attention is paid to the permeability of reservoirs, since this parameter is the most important for development and production. At the next stage, specialists move on to creating a three-dimensional geological model. It takes into account the effects of heterogeneity at the creation stage. After checking the quality of the model development, a simulation model is created on the basis of the geological one. The obtained results show that for the intercoal strata of the J1M formation, just like for J11 and J13 formations, it is advisable to use the method for determining the permeability anisotropy parameters. The magnitude and direction are confidently identified and reflect the dominant hydrocarbon filtration direction. Results. The characteristics of the heterogeneity of the J1M formation were studied by previously tested methods. Thus, the scheme of calculations for the J13 reservoir remains unchanged. Visual analysis is carried out on the basis of constructed rose diagrams and distributions of values in the form of histograms. The trend of the J1M formation form is as follows: the orientation of the first maximum varies from 150° to 180°, and the second – from 330° to 360° northwest (southeast) direction.

Keywords

• permeability anisotropy
• anisotropy scale
• petrophysics
• terrigenous reservoir
• intercoal strata