METHOD OF EVALUATING PRESSURE IN UNDERGROUND RESERVOIRS Russian patent published in 2009 - IPC E21B49/00 E21B47/06 

FIELD: oil and gas production.

SUBSTANCE: invention refers to oil producing industry and is designed for evaluating properties of reservoirs surrounding underground well. To achieve the object of the invention the method consists in recording time after completion of drilling at the depth interval, in determining permeability of reservoirs at the depth interval, in generating time cycling of pressure in a borehole of the well and in assessing periodic and un-periodic constituents of pressure measured in reservoirs at the depth interval. By time, periodic constituent and permeability there is determined coefficient of diffusion of pressure and water-permeability of reservoirs, also there is assessed area of zone of pressure build-up around the borehole of the well at the depth interval. Further, by time, coefficient of diffusion of pressure, water-permeability of reservoirs and un-periodic constituent there is determined an indicator of filtration of clay coating at the depth interval. By the indicator of filtration there is evaluated pressure gradient at the depth interval and extrapolation is carried out to determine reservoir pressure by pressure gradient and by area of zone of pressure build-up.

EFFECT: upgraded accuracy of evaluation of primary reservoir pressure due to more accurate determining parametres of filtrate leakage.

21 cl, 15 dwg