Nuclear magnetic resonance gas isotherm technique to evaluate reservoir rock wettability

摘要

Nuclear magnetic resonance (NMR) gas isotherm techniques to evaluate wettability of porous media, such as hydrocarbon reservoir rock, can include constructing a NMR gas isotherm curve for a porous media sample gas adsorption under various pressures. A hydrophobic or hydrophilic nature of the porous media sample can be determined using the NMR gas isotherm curves. A wettability of the porous media sample can be determined based on the NMR gas isotherm curve. The wettability can be determined for porous media samples with different pore sizes. In the case of reservoir rock samples, the determined wettability can be used, among other things, to model the hydrocarbon reservoir that includes such rock samples, to simulate fluid flow through such reservoirs, or to model enhanced hydrocarbon recovery from such reservoirs.

主权项

1. A method comprising:
applying a plurality of pressures to a three-dimensional reservoir rock sample in a closed volume, the reservoir rock sample comprising a plurality of porous regions distributed along a longitudinal axis of the reservoir rock sample, wherein the plurality of porous regions have a respective plurality of wettabilities, each wettability representing a quality of each porous region to absorb water; at each pressure of the plurality of pressures, applying a spin-echo single-point imaging (SE-SPI) pulse sequence to the plurality of porous regions distributed along the longitudinal axis of the reservoir rock sample; constructing a nuclear magnetic resonance (NMR) gas isotherm curve for the reservoir rock sample in response to applying the plurality of pressures and, at each pressure of the plurality of pressures, applying the SE-SPI pulse sequence to the plurality of porous regions distributed along the longitudinal axis of the reservoir rock sample; determining the plurality of wettabilities for the plurality of porous regions based on the NMR gas isotherm curve, each wettability of the plurality of wettabilities including a value representing the quality of each porous region to absorb water; determining a spatial wettability distribution for the reservoir rock sample based on the plurality of wettabilities; and providing the spatial wettability distribution for the reservoir rock sample.