Chevron U.s.a. Inc.

Haijing Wang

Boqin Q Sun

Scott Jeffrey Seltzer

Emmanuel Toumelin

Hanming Wang

John S Zintsmaster

Hussein Alboudwarej

A method for determining water-filled porosity and water salinity in a well includes obtaining complex dielectric permittivity of earth formations, either from dielectric measurements representative of well cores, or from dielectric well logs; selecting a dielectric mixing law for the index number m; plotting a m-th root of complex dielectric permittivity at a specified frequency in the complex domain, wherein m is an index number; determining a matrix permittivity, a water salinity, and a water-filled porosity based on the complex dielectric permittivity and the dielectric mixing law; and displaying the water salinity and the water-filled porosity.

System and method for determining water-filled porosity and water salinity in well cores and logs

To measure the phase behavior of a fluid in a porous medium such as a tight gas shale, one illustrative method involves: (a) loading the fluid into a sample cell containing the porous medium; (b) setting a pressure and a temperature for the fluid in the sample cell; (c) applying an RF pulse sequence to the fluid in the sample cell to acquire an NMR signal; (d) deriving from the NMR signal an NMR parameter distribution that depends on the pressure and the temperature; (e) determining whether a fluid phase is present based on the NMR parameter distribution; (f) repeating operations (c) through (f) to determine the presence or absence of the fluid phase at multiple points along a pressure-temperature path that crosses a phase boundary; and (g) providing an estimated location of the phase boundary based on the presence or absence of the fluid phase at said points.

NMR measured pore fluid phase behavior measurements

A sensor and a method are disclosed for analyzing fluid and/or rock samples from a subsurface formation. Embodiments of the sensor and method utilize an array of magnets arranged in a specific way. The array and its arrangement may allow for NMR analysis of multiple samples or analysis of fluid samples which were not possible with existing technology. Further details and advantages of various embodiments of the method are described in more detail herein.

NMR sensor for analyzing core or fluid samples from a subsurface formation

An NMR sensor and method is disclosed for analyzing a core sample from a subsurface formation. Embodiments of the method utilize two or more magnets disposed proximate to each other. The configuration of the magnets allows for increased detection frequency, and creates a strong field with much finer resolution than existing designs. In addition, embodiments of the sensor may be used at the well site due to its small size and simple hardware. Further details and advantages of various embodiments of the method are described in more detail herein.

Mobile NMR sensor for analyzing subsurface samples

A disclosed method for characterizing gas adsorption on a rock sample includes: measuring a nuclear magnetic resonance (NMR) response of the rock as a function of surrounding gas pressure along an isotherm; transforming the NMR response to obtain a Langmuir pressure distribution of gas adsorption on the rock sample; and displaying the Langmuir pressure distribution. The Langmuir pressure distribution may be shown in one dimension (e.g., contribution to signal response versus Langmuir pressure), or may be combined with additional pressure-dependencies such as spin-lattice relaxation time (T), spin-spin relaxation time (T), and chemical shift (&#x3b4;) to form a multi-dimensional distribution. The method can further include: identifying peaks in the Langmuir pressure distribution; and associating a gas storage mechanism and capacity with each peak. It may still further include: exposing the rock sample to a treatment fluid to obtain an altered sample; repeating said measuring and transforming operations with the altered sample; and comparing the Langmuir pressure distributions to determine effects of the treatment.

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Sugar Land, TX, United States of America

Haijing Wang