Specific features of the probability petrophysical estimation of rock formations using the approaches of the concept of porous space connectedness

Abstract

Background. The technology of probability petrophysical estimation of parameters using layer-bylayer interpretation of well logging data is present in this paper. Specific features of the technology is to using both the vertical and horizontal processing.
 Aim. The aim of the technology is the possibility of its adaptation when interpreting well logging data using the approaches of the concept of pore space connectedness, which reduce the variability of estimates of productive thicknesses of reservoirs in comparison with traditional approaches to calculating geological reserves using fixed cutoff porosity coefficient.
 Materials and methods. The paper discusses the main features of modeling the uncertainties of the input parameters and ways of representing them in the form of various distributions with a description of a generalized algorithm for the probabilistic assessment of geological reserves. The distributions of the reservoir area, oil density and conversion factor, the basic version of the results of the reservoir logging data interpretation in the form of a table continuous in depth with readings from the logging methods curves in intervals homogeneous in lithology are use as input parameters when executing the algorithm. In addition, distributions reflecting variations in the uncertainties of geophysical parameters, constants of petrophysical models, boundary cutoff s for identifying reservoirs and assessing their saturation nature are used to the input of the algorithm.
 Results. An algorithm for probabilistic petrophysical assessment has been developed taking into account the use of petrophysical modeling within the framework of the concept of pore space connectivity and the layer-by-layer mode of interpretation of well logging data. It is shown that additional petrotyping, which makes it possible to clarify the parameter of pore space connectivity, reduces the error of the resulting estimates, which can reduce the risk of making ineffective decisions.
 Conclusions. It is show that additional petrotyping, which makes it possible to clarify the parameter of pore space connectedness, reduces the error of the resulting estimates, which can reduce the risk of making ineffective decisions.