Estimation of displacement coefficient with due account for hydrophobization of reservoir using geophysical data of wells

Abstract

AnnotationThe coefficient of oil displacement by water from productive reservoirs is one of the main parameters reflecting the efficiency of oil field development by maintaining reservoir pressure. This parameter is necessary for both calculation of reserves and composition of technological scheme and project for oil field development. The displacement coefficient is important information for localization of residual reserves of developed oil fields and for estimation of oil production dynamics and effectiveness of methods for intensification of oil field development and oil recovery. In reservoirs of Western Siberia, during the displacement of oil by water from voids of productive reservoirs, residual oil has two components: capillary trapped oil and adsorbed oil on the surface of clay aggregates as separate droplets and films. The work demonstrates that the fraction of capillary trapped oil can be estimated using the value of effective reservoir porosity, since it characterizes the correlation of the size of pores and interpore narrowings. The content of adsorbed hydrocarbons on the active surface of pores depends on the clayiness and activity of clay, and on wetting ability of oil as well. The clayiness of reservoir is proportional to its residual water content and tightly connected with initial oil content of the productive reservoir. The present work shows the possibility of taking into account the effect of hydrophobization of a reservoir on the residual oil content using the value of initial reservoir charge. Noteworthily, the effective porosity and initial reservoir charge with practically useful accuracy can by estimated using the data of conventional complex of geophysical surveys of wells.