Schlumberger Technology Corporation

Saudi Arabian Oil Company

Services Petroliers Schlumberger

Gong Li Wang

Dean M Homan

Thomas D Barber

John C Rasmus

Aria Abubakar

Peter T Wu

Keli Sun

Ping Zhang

Shouxiang Mark Ma

Wael Abdallah

Koji Ito

David Furse Allen

Anas Mohammedali Almarzooq

Xiao Bo Hong

Tianxia Zhao

Natalie Uschner-Arroyo

Charles A Johnson

Sherif Ghadiry

Tariq Alshaikh Mubarak

Thomas Daniel Barber

Properties of a geological formation, such as dielectric constant and conductivity, may be determined by a propagation well log data acquired by a propagation well logging tool based at least in part on a relative longitudinal position of two or more receivers of the propagation well logging tool. In some embodiments, the relative longitudinal position of the at least two receivers is based at least in part on a first distance between a first receiver of the at least two receivers and a transmitter of the propagation well logging tool and a second distance between a second receiver of the at least two receivers and the transmitter.

Determining formation conductivity with propagation measurements

Methods and systems are provided for characterizing connate water salinity and resistivity of a subsurface formation. Well log data including resistivity and spontaneous potential (SP) log data are measured by at least one downhole tool disposed within a borehole. The resistivity and SP log data are inverted to determine a resistivity model and an SP model, which are used to determine connate water resistivity. The connate water resistivity is used to determine connate water salinity. The connate water salinity derived from the inversion of resistivity log data and SP log data (or derived from a trained ML system supplied with such log data) can be used as a baseline measure of connate water salinity, and this baseline measure can be evaluated together with the connate water salinity estimates derived from pulsed neutron tool measurements over time-lapsed periods of production to monitor variation in connate water salinity due to production.

Methods for predicting and monitoring downhole salinity variations

A method can include receiving dielectric data from a downhole dielectric tool of a drillstring disposed in a borehole in a target material that includes a target material boundary between the target material and one or more other materials; generating a geosteering command, based at least in part on the dielectric data, that calls for orienting a drill bit of the drillstring with respect to the target material boundary; and issuing the geosteering command to a geosteering actuator of the drillstring.

Dielectric-based geosteering

Methods and systems are provided that use resistivity log data to estimate water saturation of formation rock and/or other useful formation parameters (such as CEC) in a manner that accounts for one or more electrically conductive mineral components contained in the formation rock.

Water saturation estimation of pyrite-rich formation rock

Properties of a geological formation, such as vertical resistivity values, horizontal resistivity values, dip, and azimuth may be determined by inverting electromagnetic (EM) well log data based at least in part on an anisotropic formation model and a cost function. The cost function may include a data misfit term, a smoothness term, and an entropy term. In some embodiments, one or more of the data misfit term, the smoothness term, and the entropy term may be represented as functions of vertical conductivity and horizontal conductivity. The cost function may include one or more regularization parameters that are based at least in part on the data misfit term. Further, the cost function may include one or more relaxation factors that are based at least in part on a ratio of the Hessians of the smoothness term and the data misfit term.

Determining anisotropic subsurface properties with electromagnetic measurements

The highly valuable properties of resistivity and dielectric constant of a geological formation may be determined using an induction measurement, even for a geological formation with bed boundary or dipping effects, using a one-dimensional (1D) formation model. Induction measurements may be obtained in a wellbore through the geological formation using one or more downhole tools. One or more processors may be used to perform an inversion to estimate resistivity and dielectric constant values of the geological formation. The inversion may be performed using the induction measurements and a one-dimensional model that includes a number of geological layers.

Determining dielectric constant and resistivity with induction measurement

A formation characterization system can include a processor; memory accessibly by the processor; instructions stored in the memory and executable by the processor to instruct the system to: acquire induction measurements in a borehole in a formation using an induction tool; determine dielectric properties of the formation using the induction measurements; and generate a log that characterizes particles in the formation based on the dielectric properties.

Formation characterization system

Identifying the dielectric constant and/or the electrical resistivity of part of a geological formation may reveal useful characteristics of the geological formation. This disclosure provides methods, systems, and machine-readable media to determine dielectric constant or electrical resistivity, or both, using contraction mapping. Specifically, contraction mapping may be used with a function of wavenumber k to iteratively solve for values of dielectric constant and electrical resistivity until convergence is achieved. This may allow for convergence to a solution without computing partial derivatives and/or with fewer iterations than previous techniques.

Systems and methods for determining dielectric constant or resistivity from electromagnetic propagation measurement using contraction mapping

A method for determining resistivity of subsurface formations includes generating an initial model of the formations from multiaxial electromagnetic transimpedance measurements, the model comprising values of vertical resistivity, horizontal resistivity, crossbed dip, crossbed azimuth, and bedding dip and azimuth. Expected measurements generated from the initial model measurements are decomposed into ordinary and extraordinary components. The actual tool measurements are compared to the summation of the expected decomposed measurement components. The initial model is adjusted, the expected decomposed components are recalculated and the foregoing are repeated until the difference between the actual tool measurements and the summation of the expected decomposed components falls below a selected threshold.

Multiaxial well logging instrument response in dipping and crossbedded formations

A method for logging a formation or sample includes obtaining a plurality of multiaxial conductivity measurements from the formation or sample. A horizontal resistivity measurement, a dip measurement and a dip azimuth measurement are derived from the plurality of multiaxial conductivity measurements. A sharp vertical resistivity measurement is derived from a subset of the plurality of multiaxial conductivity measurements.

Adaptive inversion for vertical resistivity logs from multiaxial induction measurements

A method to determine at least one formation property of a subterranean formation includes providing a downhole electromagnetic logging tool having at least one transmitter array and one receiver array to acquire measurements in the formation. The method further includes performing a first inversion in response to the measurements, assuming dip or dip azimuth is constant in an inversion zone within the formation to obtain an inverted formation model. The method includes determining an n-th order partial derivative matrix of at least one of dip or dip azimuth, wherein n is greater than or equal to 1. The method includes performing a second inversion using the determined n-th order partial derivative matrix, wherein at least one of dip and dip azimuth are allowed to vary in the inversion zone, to obtain an updated formation model. The method includes determining the formation property using the updated formation model.

Extended 1D inversion of electromagnetic measurements for formation evaluation

A system and method discloses performing a fracture operation at a wellsite about a subterranean formation. The method involves, obtaining wellsite measurements by placing a downhole tool in a wellbore and using the downhole tool to acquire measurements of the subterranean formation, simulating the obtained wellsite measurements to determine formation parameters comprising conductivity tensors based on a formation model of the measured subterranean formation, validating the formation model by comparing the obtained wellsite measurements with the simulated wellsite measurements, generating fracture parameters and triaxiality indicators based on the validated formation model, and fracturing the subterranean formation based on the generated fracture parameters and triaxiality indicators.

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Sugar Land, TX, United States of America

Gong Li Wang