Physical property measurements of rock core samples

Abstract

Methods and systems for physical property measurements of rock core samples are disclosed.

Description

[0001] PHYSICAL PROPERTY MEASUREMENTS OF ROCK CORE SAMPLES

[0002] RELATED APPLICATION

[0003] This application claims priority to U.S. Provisional Application No. 63 / 587,374, filed October 2, 2023, the entire contents of which is hereby incorporated by reference herein.

[0004] BACKGROUND

[0005] A rock core sample is a cylindrical section of a substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The hole made for the core sample is called the "core hole". A variety of core samplers exist to sample different media under different conditions; there is continuing development in the technology In the coring process, the sample is pushed more or less intact into the tube. Removed from the tube in the laboratory, it is inspected and analyzed by different techniques and equipment depending on the type of data desired.

[0006] Accurate physical property measurements on rock core samples returned from drilling is important for reconstructing subsurface geology. Some physical properties, such as electrical conductivity, are difficult to measure. Often, extremely high contact resistance between the measurement electrodes and the rock or diode effects from non-ohmic contacts prevent accurate measurements. Also, in some samples, conductivity can be highly anisotropic, with significant differences in the electric conductivity along different axes or planes in the rock. Electrodes soaked in copper salt solutions can overcome some of the contact challenges, but are operationally challenging, contaminate the sample with copper, and can only measure conductivity along the core axis direction. Often a magnetic eddy-current technique for measuring conductivity is used, but this approach suffers from difficulty in measuring conductivity over length scales that are important for modeling geophysical responses of conductive rock used in mineral exploration. Accordingly, improved methods for making conductivity measurements on rock core samples are needed.

[0007] SUMMARY

[0008] This specification describes systems and measurement techniques that utilize multipoint probes for electrical measurements of rock core samples. The probes conform to the sample surface, ensuring good physical contact with the rock core sample. The measurements can include measurement of geometric factors between probes to improve accuracy of conductivity readings. Furthermore, measurement of other physical properties, such as chargeability and / or magnetic susceptibility can also be performed.

[0009] Other features and advantages will be apparent from the drawings, the description, and the claims.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1A is a schematic diagram of an example system for measuring physical properties of a rock core sample.

[0012] FIG. IB is another schematic diagram of the example system shown in FIG. 1A.

[0013] FIG. 1C is a perspective view of an example probe from the example system shown in FIG. 1A.

[0014] FIG. ID is a plot of an example of a current-voltage curve.

[0015] FIG. 2A is a perspective view of another example probe.

[0016] FIG. 2B is a perspective view of yet a further example probe.

[0017] FIG. 3 is a perspective view of another example probe.

[0018] FIG. 4 is a perspective view of still a further example probe.

[0019] FIG. 5 is a schematic diagram of an example electronic processing apparatus suitable for use in a system for measuring physical properties of a rock core sample.

[0020] In the drawings, like symbols denote like elements.

[0021] DETAILED DESCRIPTION

[0022] Referring to FIG. 1A-1C, a system 100 for measuring electrical conductivity of a rock core sample 101 includes a pair of probes 110 and 120 and an electronic control and measurement module 130 (e.g., a computer in combination with a signal generator and voltmeter) connected to the probes by leads. Each probe 110 and 120 include a pair of electrodes that are electrically isolated from each other. Specifically, probe 110 includes electrodes 111 and 112 and probe 120 includes electrodes 121 and 122. Electrodes 111 and 112 are separated by an insulating block 113. Electrodes 121 and 122 are separated by another insulating block 123.

[0023] Rock core samples 101 is a cylindrical sample, which is a common form for a core sample. Cylindrical core samples can have a diameter in a range from 50 mm up to 200 mm (e.g., 80 mm to 120 mm). The axial length of a cylindrical core sample can be as short as 8 cm up to 200 cm.

[0024] The system 100 can be a portable system, for example, weighing about 10 kg or less with each of the components (e.g., the probes and module 130) being sized and shaped to be hand carried. The system 100 can be battery powered and / or can include a power supply that plugs into a wall socket.

[0025] Each of the electrodes include a flexible, compressible terminal. Specifically, electrodes 111 and 112 include terminals 115 and 116, respectively, and electrodes 121 and 122 include terminals 125 and 126. The terminals are formed from an electrically conducting, flexible material or assembly that can be compressed against the core sample 101. An example is an electrically conducting wire mesh, such as a metal wool (e.g., copper, aluminum, steel), which can be compressed against the surface of the core sample 101, creating good electrical contact with the core sample.

[0026] The compressible terminals each have a dimension (e.g., a length) sufficiently large to provide to provide contact to the core sample 101 surface along a line that provides contact to a reasonable length of the sample surface. For example, each terminal can have a length of 0.5 mm or more (e.g., 1 cm or more, 2 cm or more, 3 cm or more, such as 10 cm or less, 5 cm or less). The perpendicular dimension (e.g., width) of the terminal can be similar or, in the case of a linear terminal, smaller than the large dimension. For example, each terminal can have a width of 1 cm or less (e.g., 0.5 cm or less, 0.2 cm or less, 0.1 cm or less).

[0027] The conformal contact of the electrodes to the sample surface generally allows for good electrical contact with any conducting grains at the core sample surface, even though curved and, sometimes, rough. The electrical contact is generally sufficient for the four-point resistivity measurements (described below) without, e.g., having to include a conducting liquid or gel at the surface to facilitate sufficient contact.

[0028] As noted previously, in each probe, the electrodes are separated by an insulating block. Generally, the insulating block is formed from an electrically insulating material that is sufficiently rigid to maintain a fixed distance between the separated electrodes and prevent electrical connection between the electrodes (i.e., between 111 and 112, and 121 and 122). Generally, no potential difference is actively applied between 111 or 112, and also between 121 and 122, but it is still desirable to maintain high electrical resistance between 111 and 112, as well as between 121 and 122. This distance can be in a range from 0.5 mm to 1 cm, for example. Examples of appropriate dielectric materials include insulating rubber and / or other organic polymeric materials. The dielectric materials should exhibit some degree of physical compliance (e.g., sufficient to allow 111 to rotate and / or move relative to 112, and same for 121 and 122), and high electrical resistance. Separation should be small compared to the radius of the sample, 101, being measured, e.g., no larger than about 1 / 4 of that radius. The closer the electrodes in general, the more accurate and less susceptible to sample inhomogeneity this technique will be. , no larger than about 1 / 4 of that radius. The closer the electrodes in general, the more accurate and less susceptible to sample inhomogeneity this technique will be. When positioned with the electrode terminals contacting the core sample 101, one electrode from each probe form part of a first circuit and one electrode from each probe form a second circuit, parallel circuit. As depicted in FIG. IB, electrodes 111 and 121 form a circuit A and electrodes 112 and 122 form a circuit B. In order to perform a four-point conductivity measurement, a current at a preset value is applied to one of the circuits (the force connections) while a potential difference between the electrodes is measured for the other circuit (the sense connections). These currents can range from microamps or even nanoamps for high resistance samples, up to one amp or more for highly conductive samples. This circuit, in addition to having a target current, has a compliance voltage which prohibits the applied voltage from going above that level. These compliance voltages can be controlled automatically during the measurement by the measurement device 130 so as to avoid sparking. The compliance voltage in general can be started at a low value (e g., 0.1 V), then once some connection to the sample is sensed, can be ramped up, e.g., to as high as 1,000 V or more. In certain implementations, voltages can be maintained at lower levels (e.g., 50 V or less) to reduce risk of dangerous electrical shocks. The contact can be sensed electrically as a low-level current in the sample, or can be sensed physically by pressure sensors in the probes, for example.

[0029] Generally, the preset current value can vary depending on the composition of the core sample. The current can be sufficient to register a large voltage change between the electrodes of the second circuit (e.g., 5 V or more, 10 V or more, 20 V or more, such as 50 V or less, 30 V or less) For highly conductive samples (e.g., samples with a resistance of 10 ohms or less, such as 1 ohms or less) a smaller difference in voltage should be present (e.g., 1 V or less, 0.1 V or less), but due to the good electrical contact between the electrodes and rock samples with high conductivity, these voltages are sufficient to make a good conductivity measurement.

[0030] During the measurement cycle, the system 100 switches the direction of current flow between the force connections. Reversing the current flow can reduce the effect of any diodic effects of the core sample 101 in the circuits. The magnitude of the current applied in both directions can be the same or different. In some cases, voltage measurements are made at more than one current value (e.g., in each direction). For example, measurements can be made for current values over a large dynamic range. For instance, the current can be ramped between - 0.1 A and 0.1 A, with the resulting voltage being measured at 200 incremental currents separated by 0.001A each. This generates current-voltage, or I-V, curve, an example of which is shown in FIG. ID. By then measuring the slope of this line at the extrema (e.g., the last 10% or so of the positive and negative current range) and applying geometric correction factors based on the sample and probe geometries, a good estimate of the effective internal sample conductance in the direction between the probes can be determined. By measuring the difference between this "extrema" slope and the slope near zero current, a contact resistance between the probes and the sample can be determined. Finally, by measuring the offset of the entire I-V curve from crossing I = 0, V = 0, the diodic characteristics of the contact-to-sample connection can be determined. Usually, the sample resistance is what is most interesting and important, but the measurements of the contact resistance and the diodic properties of the contacts can also be interesting and important as well, both for the purposes of characterizing the sample more fully, as well as for verifying that good electrical contact was made. Also, by comparing the determined voltage at positive and negative maximal current, the quality of the measurement can be additionally determined (they should ideally be equal and large differences in the determined conductances for different polarity and / or different force / sense probe configuration (see below) can be indicative of a problem with the measurement).

[0031] Conductivity of the core sample is determined from the known current and measured voltage using Ohm’s law. The conductivity can be determined as the average from measurements made with the current flowing in each direction.

[0032] The measurement cycle can also include switching the operation of circuit A from the force circuit and circuit B from sense circuit so that circuit B operates as the force circuit and circuit A operates as the sense circuit. Between switching the circuit operation and switching the polarity of the circuit in each configuration, a total of four measurements can be made for each measurement cycle. Multiple measurement cycles can be performed with the probe locations fixed, e.g., at different current values, and a resistivity of the sample calculated for each measurement cycle using Ohm’s law.

[0033] The system can calculate geometric factors between probes and use the geometric factors to improve accuracy of electrical conductivity measurements. Generally, this is necessary because there is a voltage drop between where the "force" probes make contact to the sample, and where the "sense" probes make contact.

[0034] Other physical properties, in addition to electrical conductivity, can be measured using system 100. For example, measurements of chargeability on the rock core sample 101 can be performed using the measurement system 100 without moving the core sample. The system 100 can calculate chargeability based on a time of voltage decay across the probes after a voltage is applied. This is done by apply a current between force probes for a relatively extended period of time (e.g., until the measured resistance plateaus), then abruptly disconnecting the current circuit (e.g., inside the control box, rather than by removing the contacts from the sample). Upon disconnecting, the voltage drops almost instantaneously down to an intermediate value between the full voltage and zero, and then decays relatively slowly to zero over the course of a time period on the order of seconds (e.g., the force and sample time can be varied, for instance Is each, 2s each, 10s each). By measuring the initial voltage and the decay of the voltage, a level of chargeability in the sample can be determined. This is another electrical characteristic of rock samples that can be important to measure for mineral exploration. The same system and probes that can measure electrical conductivity can measure chargeability. Chargeability can be measured in the same direction, or in a perpendicular direction as conductivity (e.g., axial and transverse). Measuring chargeability in a perpendicular direction to the maximum direction of conductivity may enable more accurate chargeability measurement by reducing the effect of high conductivity on the measurement.

[0035] FIG. 1A shows the probes positioned to perform a transverse measurement on the full core sample, however other measurements are possible. For example, the probes can be positioned to perform axial measurements too (i.e., one probe is positioned at one end of the cylindrical core, and the other is placed at the opposite end). Measurements can also be performed on fractional core samples. For example, measurements can be performed on a half core sample (i.e., the core is cut in half along its length), a quarter core sample (i.e., the core is cut into quarters along its length), or other fractional sample.

[0036] In some examples, system 100 can include more than one pair of probes (e.g., two, three, or four probe pairs). More than one pair of probes allows the system to measure physical properties of a core sample along more than one path contemporaneously. For instance, system 100 can be arranged to measure transverse conductivity using one set of probes (e.g., as illustrated) and axial conductivity using another. The control module 130 can switch measurements between the probes during a measurement cycle.

[0037] While the example system 100 shown in FIGS. 1 A-1C include probes that each include a single pair of electrodes, other configurations are possible. For example, probes can include more than one current electrode and / or more than one voltage electrode. Furthermore, while the compressible terminals of probes 110 and 120 are linear strips (e.g., contact the core sample 101 along a strip having an aspect ratio of 2: 1 or more, such as 3 : 1 or more, 5: 1 or more, 10:1 or more), other form factors for the terminals can be used. For instance, electrode terminals can be linear, point-like, or gridded arrangements of multiple points. Point-like tips contact the core sample surface at a point-like (e.g., circular) area that is relatively small (e.g., a diameter of 2 mm or less, 1 mm or less, 0.5 mm or less, 0.1 mm or less). In some implementations, a conductive elastomer (see, e.g., https: / / en.wikipedia.org / wiki / Elastomeric_connector) can be used to form the terminal. In certain cases, spring loaded metal shims (e.g., linear shims) or pins (e.g., pogo pins) can be used.

[0038] Referring to FIG. 2A, an example probe 210 includes an array of point like electrode terminals 211 and 212 protruding from a face 213 of the probe. The terminals are arranged in a regular two-dimensional array and alternate between terminals 211 and terminals 212 in a series of rows and columns. When contacted to a surface of a core sample, the terminals 211 form multiple parallel connections to the sample. Similarly, terminals 212 for a second set of parallel connections to the sample.

[0039] The terminals 211 and 212 can be formed as pogo pin connectors, each being spring loaded so that they can recede into the face 213 of the probe when pressed against the sample. This can ensure good physical contact of each (or at least a subset) of the terminals when pressed against a curved, rough surface of the core sample. As another example, referring to FIG. 2B, a probe 230 includes an array of linear electrode terminals 221 and 222. The terminals 221 form a pair of parallel connections for one of the current or sense circuits, while terminals 222 for a pair of parallel connections for the other. The linear electrode terminals can be formed from a compressible, flexible material as described previously.

[0040] In the foregoing examples the probe electrodes are depicted as having flat faces on which the conformal terminals are placed, however other implementations are possible. For example, referring to FIG. 3, a probe 310 includes a concave face 320 which can be shaped to conform to a core sample having a specific radius of curvature. For example, the concave face 320 can have curvature in one direction only with the same, or similar, radius of curvature as the cylindrical rock core sample. Probe 310 includes an array of point-like terminals 311 and 312 (e.g., pogo pin connectors) which protrude from the concave face. Each terminal can have an axis that is aligned the surface normal of the concave face 320 at the location of the terminal. Although only eight terminals are shown, generally, the probe 310 can include fewer or more than eight terminals.

[0041] The probes described above are separate handheld probes and their use generally involves a technician placing them by hand against the core sample 101 for measurements. However, other form factors are possible. For example, the two probes can be mechanically attached to each other and moveable relative to each other only about limited degrees of freedom. An example of such probes is shown in FIG. 4, where a probe assembly 410 includes a pair of probes 420 and 430 connected along an edge by a hinge 440. Each probe is composed of a module with a concave face and an array of point-like terminals protruding from the concave face. In particular, probe 420 includes terminals 421 and 422 while probe 430 includes terminals 431 and 432. While just a single row of terminals is depicted on each probe in FIG. 4, the array can extend down the axial length of the probes, forming a two-dimensional array. As described previously, terminals 421 and 431 form a first circuit when contacted to the rock core sample 101 and terminals 422 and 432 form a second circuit.

[0042] During use, the probe assembly is opened at hinge 440 to facilitate easy removal and placement of the rock core sample 101 on probe 430. Then, probe 420 is folded onto the core sample, allowing terminals 421 and 422 to contact the sample surface too.

[0043] Generally, the probe assembly 410 is sized and shaped to accommodate the rock core sample, so that the terminals on the two probes are placed appropriately on the sample surface. For example, the assembly can hinge so that the terminals extend over opposite sides of the rock core sample, providing a conductivity measurement of a path than passes through the center of the core sample.

[0044] In some cases, the system can perform additional physical measurements of a core sample in addition to the four-point conductivity / resistivity measurements described above. For example, the system can include a scale that measures the weight of the core sample. The system can also include magnetic susceptibility measurements on the core sample.

[0045] Once a set of electrodes such as shown in 410 is secured to a sample, the electronic control module can switch electrical connections between electrode and conduct both lateral (e.g., by energizing probes as described for 210) or axial (e.g., by energizing one set of rings of pins at one point on the sample - one ring being "force" and one ring being "sense", or an alternating checkerboard pattern similar to this. Another similar ring can be energized down the sample some length (e.g., 5 cm or more, 10 cm or more, up to 1 m or more) to measure axial conductivity. Similar changes in conductive pin configurations can be energized and chargeability measurements along different directions can be performed to measure differences in chargeability in different directions. This may be necessary and useful where highly conductive sheets or veins "short out" a given rock sample in one or more directions, or at one or more locations, but not in other directions or locations.

[0046] In general, the electronic control and measurement module 130 can include a computing device and a signal transceiver connected to the probes. FIG. 5 shows an example of a module 800 that includes a computer 804 in communication with a signal transceiver 801. The illustrated computer 804 is intended to encompass any computing device such as a server, a desktop computer, a 1 apt op / not ebook computer, a wireless data port, a smartphone, a personal data assistant (PDA), a tablet computing device, or one or more processors within these devices, including physical instances, virtual instances, or both. The computer 804 can include input devices such as keypads, keyboards, and touch screens that can accept user information. Also, the computer 804 can include output devices that can convey information associated with the operation of the computer 804. The information can include digital data, visual data, audio information, or a combination of information. The information can be presented in a graphical user interface (UI) (or GUI). The computer 804 can serve in a role as a client, a network component, a server, a database, a persistency, or components of a computer system for performing the subject matter described in the present disclosure. The illustrated computer 804 is communicably coupled with a network 802. In some implementations, one or more components of the computer 804 can be configured to operate within different environments, including cloud-computing-based environments, local environments, global environments, and combinations of environments.

[0047] At a high level, the computer 804 is an electronic computing device operable to receive, transmit, process, store, and manage data and information associated with the described subject matter. According to some implementations, the computer 804 can also include, or be communicably coupled with, an application server, an email server, a web server, a caching server, a streaming data server, or a combination of servers.

[0048] The computer 804 can receive requests over network 802 from a client application (for example, executing on another computer 804). The computer 804 can respond to the received requests by processing the received requests using software applications. Requests can also be sent to the computer 804 from internal users (for example, from a command console), external (or third) parties, automated applications, entities, individuals, systems, and computers. Each of the components of the computer 804 can communicate using a system bus 818. In some implementations, any or all of the components of the computer 804, including hardware or software components, can interface with each other or the interface 807 (or a combination of both), over the system bus 818. Interfaces can use an application programming interface (API) 812, a service layer 814, or a combination of the API 812 and service layer 814. The API 812 can include specifications for routines, data structures, and object classes. The API 812 can be either computer-language independent or dependent. The API 812 can refer to a complete interface, a single function, or a set of APIs.

[0049] The service layer 814 can provide software services to the computer 804 and other components (whether illustrated or not) that are communicably coupled to the computer 804. The functionality of the computer 804 can be accessible for all service consumers using this service layer. Software services, such as those provided by service layer 814, can provide reusable, defined functionalities through a defined interface. For example, the interface can be software written in JAVA, C++, or a language providing data in extensible markup language (XML) format. While illustrated as an integrated component of the computer 804, in alternative implementations, the API 812 or the service layer 814 can be stand-alone components in relation to other components of the computer 804 and other components communicably coupled to the computer 804. Moreover, any or all parts of the API 812 or the service layer 814 can be implemented as child or sub-modules of another software module, enterprise application, or hardware module without departing from the scope of the present disclosure. The computer 804 includes an interface 807. Although illustrated as a single interface 807 in FIG. 5, two or more interfaces 807 can be used according to particular needs, desires, or particular implementations of the computer 804 and the described functionality. The interface 807 can be used by the computer 804 for communicating with other systems that are connected to the network 802 (whether illustrated or not) in a distributed environment. Generally, the interface 807can include, or be implemented using, logic encoded in software or hardware (or a combination of software and hardware) operable to communicate with the network 802. More specifically, the interface 807 can include software supporting one or more communication protocols associated with communications. As such, the network 802 or the interface’s hardware can be operable to communicate physical signals within and outside of the illustrated computer 804.

[0050] The computer 804 includes a processor 806. Although illustrated as a single processor 806 in FIG. 5, two or more processors 806 can be used according to particular needs, desires, or particular implementations of the computer 804 and the described functionality. Generally, the processor 806 can execute instructions and can manipulate data to perform the operations of the computer 804, including operations using algorithms, methods, functions, processes, flows, and procedures as described in the present disclosure.

[0051] The computer 804 also includes a database 820 that can hold data for the computer 804 and other components connected to the network 802 (whether illustrated or not). For example, database 820 can be an in-memory, conventional, or a database storing data consistent with the present disclosure. In some implementations, database 820 can be a combination of two or more different database types (for example, hybrid in-memory and conventional databases) according to particular needs, desires, or particular implementations of the computer 804 and the described functionality. Although illustrated as a single database 820 in FIG. 5, two or more databases (of the same, different, or combination of types) can be used according to particular needs, desires, or particular implementations of the computer 804 and the described functionality. While database 820 is illustrated as an internal component of the computer 804, in alternative implementations, database 820 can be external to the computer 804.

[0052] The computer 804 also includes a memory 808 that can hold data for the computer 804 or a combination of components connected to the network 802 (whether illustrated or not). Memory 808 can store any data consistent with the present disclosure. In some implementations, memory 808 can be a combination of two or more different types of memory (for example, a combination of semiconductor and magnetic storage) according to particular needs, desires, or particular implementations of the computer 804 and the described functionality. Although illustrated as a single memory 808 in FIG. 5, two or more memories 808 (of the same, different, or combination of types) can be used according to particular needs, desires, or particular implementations of the computer 804 and the described functionality. While memory 808 is illustrated as an internal component of the computer 804, in alternative implementations, memory 808 can be external to the computer 804.

[0053] The application 810 can be an algorithmic software engine providing functionality according to particular needs, desires, or particular implementations of the computer 804 and the described functionality. For example, application 810 can serve as one or more components, modules, or applications. Further, although illustrated as a single application 810, the application 810 can be implemented as multiple applications 810 on the computer 804. In addition, although illustrated as internal to the computer 804, in alternative implementations, the application 810 can be external to the computer 804.

[0054] The computer 804 can also include a power supply 816. The power supply 816 can include a rechargeable or non-rechargeable battery that can be configured to be either user- or non-user-replaceable. In some implementations, the power supply 816 can include powerconversion and management circuits, including recharging, standby, and power management functionalities. In some implementations, the power-supply 816 can include a power plug to allow the computer 804 to be plugged into a wall socket or a power source to, for example, power the computer 804 or recharge a rechargeable battery.

[0055] There can be any number of computers 804 associated with, or external to, a computer system containing computer 804, with each computer 804 communicating over network 802. Further, the terms “client,” “user,” and other appropriate terminology can be used interchangeably, as appropriate, without departing from the scope of the present disclosure. Moreover, the present disclosure contemplates that many users can use one computer 804 and one user can use multiple computers 804.

[0056] Implementations of the subject matter and the functional operations described in this specification can be implemented in digital electronic circuitry, intangibly embodied computer software or firmware, in computer hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Software implementations of the described subject matter can be implemented as one or more computer programs. Each computer program can include one or more modules of computer program instructions encoded on a tangible, non-transitory, computer-readable computer- storage medium for execution by, or to control the operation of, data processing apparatus. Alternatively, or additionally, the program instructions can be encoded in / on an artificially generated propagated signal. The example, the signal can be a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. The computer-storage medium can be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of computer-storage mediums.

[0057] The terms "data processing apparatus," "computer," and "electronic computer device" (or equivalent as understood by one of ordinary skill in the art) refer to data processing hardware. For example, a data processing apparatus can encompass all kinds of apparatus, devices, and machines for processing data, including by way of example, a programmable processor, a computer, or multiple processors or computers. The apparatus can also include special purpose logic circuitry including, for example, a central processing unit (CPU), a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC). In some implementations, the data processing apparatus or special purpose logic circuitry (or a combination of the data processing apparatus or special purpose logic circuitry) can be hardware- or software-based (or a combination of both hardware- and software-based). The apparatus can optionally include code that creates an execution environment for computer programs, for example, code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of execution environments. The present disclosure contemplates the use of data processing apparatuses with or without conventional operating systems, for example LINUX, UNIX, WINDOWS, MAC OS, ANDROID, or IOS. A computer program, which can also be referred to or described as a program, software, a software application, a module, a software module, a script, or code, can be written in any form of programming language. Programming languages can include, for example, compiled languages, interpreted languages, declarative languages, or procedural languages. Programs can be deployed in any form, including as stand-alone programs, modules, components, subroutines, or units for use in a computing environment. A computer program can, but need not, correspond to a fde in a fde system. A program can be stored in a portion of a fde that holds other programs or data, for example, one or more scripts stored in a markup language document, in a single fde dedicated to the program in question, or in multiple coordinated fdes storing one or more modules, sub programs, or portions of code. A computer program can be deployed for execution on one computer or on multiple computers that are located, for example, at one site or distributed across multiple sites that are interconnected by a communication network. While portions of the programs illustrated in the various figures may be shown as individual modules that implement the various features and functionality through various objects, methods, or processes, the programs can instead include a number of sub-modules, third-party services, components, and libraries. Conversely, the features and functionality of various components can be combined into single components as appropriate. Thresholds used to make computational determinations can be statically, dynamically, or both statically and dynamically determined.

[0058] The methods, processes, or logic flows described in this specification can be performed by one or more programmable computers executing one or more computer programs to perform functions by operating on input data and generating output. The methods, processes, or logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, for example, a CPU, an FPGA, or an ASIC.

[0059] Computers suitable for the execution of a computer program can be based on one or more of general and special purpose microprocessors and other kinds of CPUs. The elements of a computer are a CPU for performing or executing instructions and one or more memory devices for storing instructions and data. Generally, a CPU can receive instructions and data from (and write data to) a memory. A computer can also include, or be operatively coupled to, one or more mass storage devices for storing data. In some implementations, a computer can receive data from, and transfer data to, the mass storage devices including, for example, magnetic, magneto optical disks, or optical disks. Moreover, a computer can be embedded in another device, for example, a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a global positioning system (GPS) receiver, or a portable storage device such as a universal serial bus (USB) flash drive.

[0060] Computer readable media (transitory or non-transitory, as appropriate) suitable for storing computer program instructions and data can include all forms of permanent / non- permanent and volatile / non-volatile memory, media, and memory devices. Computer readable media can include, for example, semiconductor memory devices such as random access memory (RAM), read only memory (ROM), phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices. Computer readable media can also include, for example, magnetic devices such as tape, cartridges, cassettes, and intemal / removable disks. Computer readable media can also include magneto optical disks and optical memory devices and technologies including, for example, digital video disc (DVD), CD ROM, DVD+ / -R, DVD-RAM, DVD- ROM, HD-DVD, and BLURAY. The memory can store various objects or data, including caches, classes, frameworks, applications, modules, backup data, jobs, web pages, web page templates, data structures, database tables, repositories, and dynamic information. Types of objects and data stored in memory can include parameters, variables, algorithms, instructions, rules, constraints, and references. Additionally, the memory can include logs, policies, security or access data, and reporting files. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0061] Implementations of the subject matter described in the present disclosure can be implemented on a computer having a display device for providing interaction with a user, including displaying information to (and receiving input from) the user. Types of display devices can include, for example, a cathode ray tube (CRT), a liquid crystal display (LCD), a lightemitting diode (LED), and a plasma monitor. Display devices can include a keyboard and pointing devices including, for example, a mouse, a trackball, or a trackpad. User input can also be provided to the computer through the use of a touchscreen, such as a tablet computer surface with pressure sensitivity or a multi-touch screen using capacitive or electric sensing. Other kinds of devices can be used to provide for interaction with a user, including to receive user feedback, for example, sensory feedback including visual feedback, auditory feedback, or tactile feedback. Input from the user can be received in the form of acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to, and receiving documents from, a device that is used by the user. For example, the computer can send web pages to a web browser on a user's client device in response to requests received from the web browser.

[0062] The term "graphical user interface," or "GUI," can be used in the singular or the plural to describe one or more graphical user interfaces and each of the displays of a particular graphical user interface. Therefore, a GUI can represent any graphical user interface, including, but not limited to, a web browser, a touch screen, or a command line interface (CLI) that processes information and efficiently presents the information results to the user. In general, a GUI can include a plurality of user interface (UI) elements, some or all associated with a web browser, such as interactive fields, pull-down lists, and buttons. These and other UI elements can be related to or represent the functions of the web browser.

[0063] Implementations of the subject matter described in this specification can be implemented in a computing system that includes a back end component, for example, as a data server, or that includes a middleware component, for example, an application server. Moreover, the computing system can include a front-end component, for example, a client computer having one or both of a graphical user interface or a Web browser through which a user can interact with the computer. The components of the system can be interconnected by any form or medium of wireline or wireless digital data communication (or a combination of data communication) in a communication network. Examples of communication networks include a local area network (LAN), a radio access network (RAN), a metropolitan area network (MAN), a wide area network (WAN), Worldwide Interoperability for Microwave Access (WIMAX), a wireless local area network (WLAN) (for example, using 802.11 a / b / g / n or 802.20 or a combination of protocols), all or a portion of the Internet, or any other communication system or systems at one or more locations (or a combination of communication networks). The network can communicate with, for example, Internet Protocol (IP) packets, frame relay frames, asynchronous transfer mode (ATM) cells, voice, video, data, or a combination of communication types between network addresses.

[0064] The computing system can include clients and servers. A client and server can generally be remote from each other and can typically interact through a communication network. The relationship of client and server can arise by virtue of computer programs running on the respective computers and having a client-server relationship.

[0065] Cluster fde systems can be any fde system type accessible from multiple servers for read and update. Locking or consistency tracking may not be necessary since the locking of exchange fde system can be done at application layer. Furthermore, Unicode data fdes can be different from non-Unicode data fdes.

[0066] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular implementations. Certain features that are described in this specification in the context of separate implementations can also be implemented, in combination, in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations, separately, or in any suitable sub-combination. Moreover, although previously described features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a subcombination.

[0067] Particular implementations of the subject matter have been described. Other implementations, alterations, and permutations of the described implementations are within the scope of the following claims as will be apparent to those skilled in the art. While operations are depicted in the drawings or claims in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed (some operations may be considered optional), to achieve desirable results. In certain circumstances, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and performed as deemed appropriate.

[0068] Moreover, the separation or integration of various system modules and components in the previously described implementations should not be understood as requiring such separation or integration in all implementations, and the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Accordingly, the previously described example implementations do not define or constrain the present disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of the present disclosure.

[0069] Furthermore, any claimed implementation is considered to be applicable to at least a computer-implemented method; a non-transitory, computer-readable medium storing computer- readable instructions to perform the computer-implemented method; and a computer system comprising a computer memory interoperably coupled with a hardware processor configured to perform the computer-implemented method or the instructions stored on the non-transitory, computer-readable medium.

[0070] NUMBERED PARAGRAPHS

[0071] In some embodiments, the inventions provided in this disclosure may be described by reference to the following numbered paragraphs.

[0072] 1. A method for measuring a physical property of a rock core sample, including: positioning a first electrode probe to contact a first location of the rock core sample, the first electrode probe including a first electrode and a second electrode electrically isolated from each other, the first and second electrodes being spaced apart from each other by a first fixed distance, the first and second electrodes each including a compressible electrically-conducting tip that contacts a surface of the rock core sample; positioning a second electrode probe to contact a second location of the rock core sample different from the first location, the second electrode probe including a third electrode and a fourth electrode electrically isolated from each other, the third and fourth electrodes being spaced apart from each other by a second fixed distance, the third and fourth electrodes each including a compressible electrically-conducting tip that contacts the surface of the rock core sample; applying an electrical current having a known magnitude between the first electrode and the third electrode; while applying the electrical current, measuring a voltage between the second electrode and the fourth electrode; determining information about the physical properties of the rock core sample based on the known magnitude of the electrical current and the measured voltage.

[0073] 2. The method of claim 1, wherein applying the electrical current includes reversing a polarity of the current between the first electrode and third electrode and the voltage is measured for the known current at both polarities. 3. The method of paragraph 1 , further including applying a second electrical current having a known magnitude between the second electrode and the fourth electrode and, while applying the second electrical current, measuring a voltage between the first electrode and the third electrode.

[0074] 4. The method of paragraph 1, wherein the first and second probes are positioned on opposing sides of the rock core sample.

[0075] 5. The method of paragraph 4, wherein the opposing sides are laterally opposing sides.

[0076] 6. The method of paragraph 4, wherein the opposing sides are axially opposing side.

[0077] 7. The method of paragraph 4, wherein the information about the physical properties includes one or more of an electrical conductivity of the rock core sample, a magnetic susceptibility of the rock core sample, and chargeability.

[0078] 8. The method of paragraph 4, wherein the physical properties are determined based on the known magnitude of the electrical current and the measured voltage based on Ohm’s law.

[0079] 9. The method of paragraph 8, wherein determining the information about the physical properties includes calculating one or more electrostatic corrections for one or more geometric factors.

[0080] 10. The method of paragraph 1, wherein the information about the physical properties includes a chargeability of the rock core sample.

[0081] 11. A system for measuring a physical property of a rock core sample, including: a first probe including a first electrode and a second electrode electrically isolated from each other, the first and second electrodes being spaced apart from each other by a first fixed distance, the first and second electrodes each including a compressible electrically-conducting tip; a second probe the second electrode probe including a third electrode and a fourth electrode electrically isolated from each other, the third and fourth electrodes being spaced apart from each other by a second fixed distance, the third and fourth electrodes each including a compressible electrically- conducting tip; and an electronic control module in communication with the first and second probes, the electronic control module being programmed to apply an electrical current having a known magnitude between the first electrode and the third electrode, while applying the electrical current, measure a voltage between the second electrode and the fourth electrode, and determine information about the physical property of the rock core sample based on the known magnitude of the electrical current and the measured voltage.

[0082] 12. The system of paragraph 11, wherein the compressible electrically conducting tips each include a compressible conducting wire mesh, a spring-loaded electrically conducting element, or an electrically conducting elastomer.

[0083] 13. The system of paragraph 12, wherein the compressible electrically conducting tips are linear tips or point-like tips.

[0084] 14. The system of paragraph 11, wherein each electrically conducting tip has a dimension of 0.5 cm or more in at least one direction.

[0085] 15. The system of paragraph 11, wherein each probe includes a concave face shaped to conform to the rock core sample.

[0086] 16. The system of paragraph 11, wherein the tips of each probe are arranged in a onedimensional array or a two dimensional array.

[0087] 17. The system of paragraph 11, further including a hinge connecting the first probe to the second probe.

[0088] 18. The system of paragraph 11, wherein the electronic control module is programmed to reverse a polarity of the electrical current and to determine information about the physical property of the rock core sample for based on a voltage measurement made for both polarities.

[0089] 19. The system of paragraph 11, wherein the electronic control module is further programmed to apply a second electrical current having a known magnitude between the second electrode and the fourth electrode, while applying the second electrical current, measure a voltage between the first electrode and the third electrode, and the information about the physical property of the rock core sample is determined based on the known magnitude of the second electrical current and the measured voltage.

[0090] 20. The system of paragraph 11, wherein the information about the physical property of the rock core sample includes a chargeability of the rock core sample.

[0091] 21. The system of paragraph 11, wherein the system is a portable system.

[0092] 22. The system of paragraph 11, further including a power supply configured to supply electrical power to the electronic control module. A number of embodiments of these systems and methods have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of this disclosure. Accordingly, other embodiments are within the scope of the following claims.

Claims

What is claimed is:

1. A method for measuring a physical property of a rock core sample, comprising: positioning a first electrode probe to contact a first location of the rock core sample, the first electrode probe comprising a first electrode and a second electrode electrically isolated from each other, the first and second electrodes being spaced apart from each other by a first fixed distance, the first and second electrodes each comprising a compressible electrically-conducting tip that contacts a surface of the rock core sample; positioning a second electrode probe to contact a second location of the rock core sample different from the first location, the second electrode probe comprising a third electrode and a fourth electrode electrically isolated from each other, the third and fourth electrodes being spaced apart from each other by a second fixed distance, the third and fourth electrodes each comprising a compressible electrically-conducting tip that contacts the surface of the rock core sample; applying an electrical current having a known magnitude between the first electrode and the third electrode; while applying the electrical current, measuring a voltage between the second electrode and the fourth electrode; determining information about the physical properties of the rock core sample based on the known magnitude of the electrical current and the measured voltage.

2. The method of claim 1, wherein applying the electrical current comprises reversing a polarity of the current between the first electrode and third electrode and the voltage is measured for the known current at both polarities.

3. The method of claim 1, further comprising applying a second electrical current having a known magnitude between the second electrode and the fourth electrode and, while applying the second electrical current, measuring a voltage between the first electrode and the third electrode.

4. The method of claim 1, wherein the first and second probes are positioned on opposing sides of the rock core sample.

5. The method of claim 4, wherein the opposing sides are laterally opposing sides.

6. The method of claim 4, wherein the opposing sides are axially opposing side.

7. The method of claim 4, wherein the information about the physical properties comprises one or more of an electrical conductivity of the rock core sample, a magnetic susceptibility of the rock core sample, and chargeability.

8. The method of claim 4, wherein the physical properties are determined based on the known magnitude of the electrical current and the measured voltage based on Ohm’s law.

9. The method of claim 8, wherein determining the information about the physical properties comprises calculating one or more electrostatic corrections for one or more geometric factors.

10. The method of claim 1, wherein the information about the physical properties comprises a chargeability of the rock core sample.

11. A system for measuring a physical property of a rock core sample, comprising: a first probe comprising a first electrode and a second electrode electrically isolated from each other, the first and second electrodes being spaced apart from each other by a first fixed distance, the first and second electrodes each comprising a compressible electrically conducting tip; a second probe the second electrode probe comprising a third electrode and a fourth electrode electrically isolated from each other, the third and fourth electrodes being spaced apart from each other by a second fixed distance, the third and fourth electrodes each comprising a compressible electrically conducting tip; and an electronic control module in communication with the first and second probes, the electronic control module being programmed to apply an electrical current having a known magnitude between the first electrode and the third electrode, while applying the electricalcurrent, measure a voltage between the second electrode and the fourth electrode, and determine information about the physical property of the rock core sample based on the known magnitude of the electrical current and the measured voltage.

12. The system of claim 11, wherein the compressible electrically conducting tips each comprise a compressible conducting wire mesh, a spring-loaded electrically conducting element, or an electrically conducting elastomer.

13. The system of claim 12, wherein the compressible electrically conducting tips are linear tips or point-like tips.

14. The system of claim 11, wherein each electrically conducting tip has a dimension of 0.5 cm or more in at least one direction.

15. The system of claim 11, wherein each probe comprises a concave face shaped to conform to the rock core sample.

16. The system of claim 11, wherein the tips of each probe are arranged in a onedimensional array or a two-dimensional array.

17. The system of claim 11, further comprising a hinge connecting the first probe to the second probe.

18. The system of claim 11, wherein the electronic control module is programmed to reverse a polarity of the electrical current and to determine information about the physical property of the rock core sample for based on a voltage measurement made for both polarities.

19. The system of claim 11, wherein the electronic control module is further programmed to apply a second electrical current having a known magnitude between the second electrode and the fourth electrode, while applying the second electrical current, measure a voltage between the first electrode and the third electrode, and the information about the physicalproperty of the rock core sample is determined based on the known magnitude of the second electrical current and the measured voltage.

20. The system of claim 11, wherein the information about the physical property of the rock core sample comprises a chargeability of the rock core sample.

21. The system of claim 11, wherein the system is a portable system.

22. The system of claim 11, further comprising a power supply configured to supply electrical power to the electronic control module.

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