Schlumberger Technology Corporation

Chanh Cao Minh

Nicholas J Heaton

Roger Griffiths

Vikas Jain

Kais Gzara

Henry N Bachman

Oliver Clinton Mullins

Abdurrahman Sezginer

Yi-Qiao Song

Robert Freedman

Cosan Ayan

Martin D Hurlimann

Charles Flaum

Ravinath Kausik Kadayam Viswanathan

Denis Heliot

Ridvan Akkurt

Darwin V Ellis

Lukasz Zielinski

Philip M Singer

Steve F Crary

Andrea Valori

Bei Gao

Jack LaVigne

Ernesto E Bordon

Michel Claverie

Baarinadh Vissapragada

Steve Crary

Marie Laure Mauborgne

Ahmad Madjidi

Wicher Wichers

Peter Weinheber

A liquid saturation may be identified from nuclear magnetic resonance (NMR) data having overlapping peaks indicative of two liquids by, generally, identifying a first endpoint based at least in part on the T2 NMR data for the first liquid, and identifying a second endpoint based at least in part on the T2 NMR data for the second liquid. Then, the liquid saturation is identified by relating a composition of the first liquid for an overlapping distribution region based at least in part on the first endpoint and the second endpoint. In some embodiments, the liquid saturation is identified based on an interpolation between the first endpoint and the second endpoint.

Systems and methods for determining liquid saturation from overlapping NMR distributions

A method for estimation of water properties and hydrocarbon properties in a subsurface formation includes acquiring a plurality of well log measurements from the subsurface formation. The water properties and the hydrocarbon properties are parameterized with respect to a selected set of well log measurements. A simultaneous or sequential inversion is performed to estimate the water properties and the hydrocarbon properties.

Estimation of fluid properties from well logs

A method for determining a wettability of a subterranean formation (or formation core) includes either deploying a nuclear magnetic resonance (NMR) logging tool in a subterranean wellbore or deploying a formation core sample in a laboratory based NMR tool. NMR measurements of the formation (or formation core) are obtained and used to compute the wettability. The NMR measurements are processed to generate a two dimensional diffusion relaxation map (a D/Tmap) which is in turn processed to compute the wettability.

NMR based reservoir wettability measurements

A method for estimation of water properties and hydrocarbon properties in a subsurface formation include acquiring a plurality of well log measurements from the subsurface formation. The water properties and the formation properties are parameterized with respect to a selected set of well log measurements. The parameterized water properties, the parameterized formation properties and the well log measurements are graphically displayed to estimate the water properties.

Determination of formation properties using graphical methods

A method for determining a volume of a constituent(s) in a geological formation may include generating an equation of state based upon log measurements for the geological formation, with the equation of state providing a correlation between the log measurements, determining a quality factor for the equation of state, and for each of a plurality of different constituents expected to be in the formation, determining a constituent compliance factor for each of the constituents. The method may further include determining an uncertainty for each constituent compliance factor, determining a likelihood that each constituent is present in the formation based upon the quality factor, the constituent compliance factor for the constituent, and the uncertainty for the constituent compliance factor, generating a volumetric model based upon the log measurements and the determined likelihoods of the constituents in the formation, and determining the volume of the constituent(s) based upon the volumetric model.

Formation evaluation using stochastic analysis of log data

A method for generating a model of a formation property includes acquiring a formation property measurement. A petrophysical quantity is inverted from the formation property measurement. A model is generated based on the inverted petrophysical quantity.

Petrophysical relationships using blind source separation techniques

The presence of hydrocarbons in a subsurface formation fluid may be inferred from a determined salt concentration. A sodium nuclear magnetic resonance (NMR) measurement of a subsurface formation is obtained and a salt concentration of the fluid in the subsurface formation is determined from the sodium NMR measurement. Various operations may be performed using the determined salt concentration such as tracking injected water, monitoring flood fronts, improving reserves estimation, and designing enhanced oil recovery. A sodium index may be determined and used in conjunction with one or more other logs to determine a saturation of the subsurface formation. The one or more other logs may include a resistivity log, a dielectric log, a capture cross section (sigma) log, and a proton NMR log. Differentiation between bound water and free water can also be achieved using the sodium nuclear magnetic resonance measurement.

Determining petrophysical properties using sodium nuclear magnetic resonance (NMR) logs

Apparatus and methods for characterizing hydrocarbons in a subterranean formation include obtaining a sample of the subterranean formation; measuring, uphole, the porosity of the sample; using a nuclear magnetic resonance (NMR) tool downhole in the borehole, sending NMR pulse sequences configured for formation pore size and measuring NMR signals that characterize the formation at a location in the formation; analyzing the signals to find a gas porosity of the formation at the location; and determining a hydrogen index (HI) of the subterranean formation from the gas porosity and from the porosity of the sample. The obtained HImay then be used in conjunction with downhole NMR measurements to find corrected gas porosities at locations of the formation.

Logging in gas shale and other unconventional reservoirs

A method of interpreting petrophysical measurement data include arranging measurements of at least one physical property of formations into a matrix representing the measurements and selecting a range of number of unobserved factors or latent variables for factor analysis. Factor analysis is performed on the measurement matrix and comprises performing factorization of measurements matrix into a number of factorsand performing rotation of the factorization results. Whether the factor loadings for each factor have achieved a 'simple structure' is determined and either each of the selected number of factors is associated with a physical parameter of the formations, or one is added to the number of factors and factor analysis and rotation are repeated until factor loadings of all factors have achieved 'simple structure' such that the each of the number of factors is associated with a physical property of the formations.

Identifying formation, matrix and fluid related characteristics from subsurface data using factor analysis

A technique utilizes the acquisition of data via nuclear magnetic resonance at multiple depths of investigation in a well region. The acquired data is processed to estimate variable fluid mixture densities at different radial depths. The variable fluid mixture densities and a radial response from a density tool, for example, can be used to calculate an effective fluid mixture density and used to interpret density logs. Other logs such as neutron log, induction resistivity log, and dielectric permittivity log can be combined with NMR. For these tools a corresponding effective formation property can be calculated and used to determine other formation characteristics, such as total porosity, total density, dielectric permittivity, electric resistivity, and formation characteristics derivable from these.

System and method for estimating formation characteristics in a well

The present disclosure relates to a method to estimate a subsurface formation property. A downhole logging tool is provided and disposed in a wellbore. Multiple measurements of various measurement types are obtained at various depths of investigation using the downhole logging tool. The multiple measurements may include natural gamma ray measurements, density measurements, resistivity measurements, nuclear measurements, and nuclear magnetic resonance measurements. The signal-to-noise ratio of the measured signals is increased using, for example, lateral stacking and multi-shell inversion. The subsurface formation property is estimated using the increased signal-to-noise ratio signals. The subsurface formation property may include porosity, adsorbed gas volume, free gas volume, bound water volume, free water volume, oil volume, and kerogen volume. A fluid analysis may be performed using a multi-dimensional nuclear magnetic resonance technique. Fluids such as water, oil, gas, and oil-based mud in the wellbore may be identified and/or evaluated.

Estimating porosity and fluid volume

A method and system for performing speed correction on nuclear magnetic resonance logging data is provided. The speed correction performed can be done on a representation of echo data received by a logging tool, and then additively applied to the echo data. Such a process can reduce or remove the amplification of noise in the echo data that is common in conventional methods of speed correction.

Methods and systems for applying speed correction fits to NMR well logging formation echo data with singular value decomposition

The present disclosure relates to a method to determine the capture cross-section of a subsurface formation at a desired depth in the formation. A database of Sigma values for known lithologies, porosities, and salinities is provided, and multiple Sigma measurements are obtained from a downhole logging tool. Within the database, Sigma values are interpolated to determine the respective depths of investigation of the multiple Sigma measurements. A monotonic function is fitted to the multiple Sigma measurements at the determined depths of investigation, and the capture cross-section of the subsurface formation at any desired depth in the formation is determined using the fitted function. Similarly, a system to determine the capture cross-section of a subsurface formation at a desired depth in the formation and/or a depth of invasion of drilling fluids is also disclosed.

Estimating sigma log beyond the measurements points

The present disclosure relates to a method to determine a characteristic of a subsurface formation using a downhole logging tool. A downhole logging tool having the ability to make substantially concurrent disparate measurements on the subsurface formation is provided and substantially concurrent disparate measurements on the formation using the downhole logging tool are made. Those measurements are used to solve a system of equations simultaneously and the solution to the system of equations is used to determine the characteristic of the subsurface formation.

Determining formation properties while drilling

A method for determining a formation type within a wellbore includes forming the wellbore such that the wellbore intersects fractures within a formation. Hydrocarbons are produced from the formation. An induction tool is disposed into the wellbore after producing the hydrocarbons. A resistivity of a portion of the formation is measured with the induction tool. The resistivity of the portion of the formation is compared with a known formation type. The formation type of the portion of the formation is determined based on the resistivity. A characteristic of the formation type is output.

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Katy, TX, United States of America

Chanh Cao Minh