Abstract: A system having an NMR measurement device make measurements on a region of investigation in which an NMR-active fluid has been injected. A source of the NMR-active fluid (e.g., methane) is provided, and the pressure of the region of investigation may be monitored. A sealing apparatus serves to isolate the region of investigation. A parameter is estimating using the obtained measurement. The parameter estimated may include the inter-granular porosity, intra-kerogen porosity, kerogen maturity, free gas volume, and/or adsorbed gas volume. A baseline measurement may be made prior to injecting the NMR-active fluid, and the region of investigation may be evacuated before injecting the NMR-active fluid. The obtained T2 distribution can be resolved and each peak attributed to different constituent sources of the signal. The system can be conveyed into a wellbore using a drillstring, a wireline, a slickline, or a coil tubing.

Abstract: In an embodiment a method is described which includes emplacing a sample within a measurement cell, wherein two or more electrodes are configured in the measurement cell; introducing a reactive fluid into the measurement cell; reacting the sample with the reactive fluid, wherein reacting the sample with the reactive fluid results in a change in an ion concentration in the reactive fluid; and measuring the resistivity of the reactive fluid using the two or more electrodes, wherein the resistivity is proportional to the ion concentration in the reactive fluid.

Abstract: A system having an NMR measurement device make measurements on a region of investigation in which an NMR-active fluid has been injected. A source of the NMR-active fluid (e.g., methane) is provided, and the pressure of the region of investigation may be monitored. A sealing apparatus serves to isolate the region of investigation. A parameter is estimating using the obtained measurement. The parameter estimated may include the inter-granular porosity, intra-kerogen porosity, kerogen maturity, free gas volume, and/or adsorbed gas volume. A baseline measurement may be made prior to injecting the NMR-active fluid, and the region of investigation may be evacuated before injecting the NMR-active fluid. The obtained T2 distribution can be resolved and each peak attributed to different constituent sources of the signal. The system can be conveyed into a wellbore using a drillstring, a wireline, a slickline, or a coil tubing.

Abstract: An antenna assembly includes a first leg extending radially over a circumference of a tool, a second leg extending axially over a length of the tool, a third leg radially over a portion of a circumference of the tool, and a fourth leg extending axially over a length of the tool.

Abstract: A downhole tool to make one or more downhole measurements of laser-induced vaporization and/or pyrolysis of hydrocarbons is provided and disposed at a desired location within a wellbore. A tool head of the downhole tool is brought into sealing engagement with the wellbore wall. The fluid within an interior region enclosed by the tool head and the wellbore wall is evacuated and a measurement spot is irradiated with a laser to generate volatile hydrocarbons and/or pyrolytic hydrocarbons. Measurements are made on the volatile hydrocarbons and/or pyrolytic hydrocarbons and one or more formation properties are inferred based on the measurements. A low level of laser radiation intensity, irradiating some or all of the wellbore wall enclosing the interior region, may be used to prevent measurement contamination, and both medium power and high power levels of laser radiation may be used to first vaporize and then pyrolyze the hydrocarbons.

Abstract: Injection fluid tuning is provided. In one possible implementation, injection fluid can be tuned by accessing both surface properties of rock found in a hydrocarbon reservoir of interest and a chemical composition of oil found in the reservoir of interest. An ion effect on wettability of a contact surface of the rock can be acquired and then used to formulate a tuned ion solution based on the ion effect on wettability of the contact surface of the rock. In another possible implementation, an electrolyte solution has an ionic composition and an ionic concentration configured to enhance recovery of oil from a reservoir. The electrolyte solution includes a content of direct contact ions including monovalent ions with a static polarizability larger than a preset limit sufficient to influence a contact surface of a rock in the reservoir to reach a desired wettability.

Abstract: Injection fluid tuning is provided. In one possible implementation, injection fluid can be tuned by accessing both surface properties of rock found in a hydrocarbon reservoir of interest and a chemical composition of oil found in the reservoir of interest. An ion effect on wettability of a contact surface of the rock can be acquired and then used to formulate a tuned ion solution based on the ion effect on wettability of the contact surface of the rock. In another possible implementation, an electrolyte solution has an ionic composition and an ionic concentration configured to enhance recovery of oil from a reservoir. The electrolyte solution includes a content of direct contact ions including monovalent ions with a static polarizability larger than a preset limit sufficient to influence a contact surface of a rock in the reservoir to reach a desired wettability.

Abstract: In an embodiment a method is described which includes emplacing a sample within a measurement cell, wherein two or more electrodes are configured in the measurement cell; introducing a reactive fluid into the measurement cell; reacting the sample with the reactive fluid, wherein reacting the sample with the reactive fluid results in a change in an ion concentration in the reactive fluid; and measuring the resistivity of the reactive fluid using the two or more electrodes, wherein the resistivity is proportional to the ion concentration in the reactive fluid.

Abstract: A tool having a pump-out unit, pumping unit, and NMR unit is disposed in a wellbore. On a pump-up cycle, after removing borehole fluids, a fluid is injected into a region of investigation. NMR measurements are made while fluid migrates into the region of investigation. On a production cycle, pressure is removed, allowing fluid to exit the formation while NMR measurements are made. A rate of fluid production is estimated using the time-dependent NMR measurements. Alternatively, the mass of a sample is measured. Fluid is injected into the sample and the mass of the injected sample is measured. Pressure is removed and the mass of the injected sample as the fluid migrates out of the sample is measured. The change in mass of the injected sample as the fluid migrates out of the sample is determined and a rate of fluid production is estimated using the determined change in mass.

Abstract: A method to obtain gain-corrected measurements. A measurement tool having one or more arrays is provided, wherein the arrays include two co-located triaxial transmitters and two co-located triaxial receivers. Measurements are obtained using the transmitters and the receivers. Impedance matrices are formed from the obtained measurements and the impedance matrices are combined to provide gain-corrected measurements. The apparatus may alternatively be a while-drilling logging tool having one or more arrays, wherein each array comprises a transmitter, a receiver, and a buck, and wherein the signal received by the receiver is subtracted from the signal received by the buck or vice versa. A slotted shield may be incorporated into either embodiment of the tool. The slots may form one or more island elements. A material is disposed in the slots. The islands and shield body have complementary tapered sides that confine the islands within the shield body.

Abstract: Sealing particles are used to stop or reduce undesired fluid loss. The sealing particles may be swellable or have effective cross-sectional areas greater than five square millimeters or are both swellable and have effective cross-sectional areas greater than five square millimeters. The sealing particles are disposed in one or more locations in which there is undesired fluid flow and, once lodged therein, stop or at least reduce the undesired fluid loss. A tubular having a bypass flow path may be used to deploy the sealing particles. The bypass flow path may use a biased or unbiased sleeve that is selectably movable to expose or block exit ports in the tubular. A retrievable sealing disk may be deployed to move the sleeve. The sealing particles may be made of a bi-stable material with extenders and may be actuated using swellable material. The sealing particles may extend in multiple dimensions.

Abstract: A NMR logging tool is provided and disposed in a wellbore at some desired depth. Packers are provided and actuated to hydraulically isolate a section of the wellbore and form a cavity between the NMR logging tool and the wall of the isolated section of the wellbore. The cavity is evacuated until a first desired pressure within the cavity is attained. Fluid is injected into the cavity until a second desired pressure within the cavity is attained. A plurality of NMR measurements is made on the region of the formation, each of the plurality of measurements being made at different times. Formation properties are inferred using the measurements. A baseline NMR measurement may be made when a first desired pressure is attained. A time-zero NMR measurement may be made when a second desired pressure is attained. Similar measurements may be made in a laboratory on a sample.

Abstract: Various triaxial antenna designs having are provided. Some embodiments include a split-z coil that can include two axial coils with saddle coils in the x- and y-directions located therebetween. The split z-coils can function by having a combined magnetic moment similar to that of a single axial coil located between the two parts of the split z-coil. In some examples, the antenna assemblies can include a protrusion or other non-planar structure.

Abstract: A downhole densitometer is used to determine one or more characteristics of a flowing fluid. The densitometer has one or more downhole x-ray sources and one or more downhole x-ray detectors. A fluid is allowed to flow past the x-ray sources. X-rays emitted by the x-ray sources and that have travelled through the flowing fluid are detected by the x-ray detectors. Characteristics of the flowing fluid are determined based on the detected x-rays. The densitometer may also have reference detectors used to measure a reference signal. The measured reference signal is used to normalize source emissions. The densitometer may be used as a permanent monitor and it may be used in conjunction with other sensors such as a flow-rate sensor or a capacitance sensor. The x-ray source may be, for example, a pyroelectric source, a radioisotopic source, or a traditional x-ray tube source.

Abstract: A measurement device makes measurements on a region of investigation in which a native fluid or complex fluid (e.g., emulsified fluid) has been replaced by a fluid of different viscosity. Various methods such as core flooding, pressure cycling, centrifuging, or imbibition may be used to replace the native fluid. The replacement fluid may include alkanes, alkenes, or some combination of those, and is preferably non-polar. The replacement fluid may mix with the native fluid within the pores to produce a mixture having a different viscosity than the native fluid. Measurements can be made on a sample in a lab or on an isolated region of a subsurface formation. Standard measurement techniques such as the Amott-Harvey technique or the United States Bureau of Mines technique may be used. Alternatively, NMR measurements may be performed. A parameter such as wettability and relaxivity is estimated using data obtained by the measurement device.

Abstract: Various triaxial antenna designs having are provided. Some embodiments include a split-z coil that can include two axial coils with saddle coils in the x- and y-directions located therebetween. The split z-coils can function by having a combined magnetic moment similar to that of a single axial coil located between the two parts of the split z-coil. In some examples, the antenna assemblies can include a protrusion or other non-planar structure.

Abstract: For a given medium, a property may be inferred based on nuclear magnetic resonance (NMR) data. NMR data that includes two or more different NMR signals are used. Differences between any particular two of the two or more different NMR decays are computed and a distribution is produced based on the computed differences. The property of the medium may be inferred using the produced distribution. The produced distribution features the change in a parameter. The NMR distributions may be T2 distributions, T1 distributions, diffusion, or any other type of NMR data. The NMR data may be acquired: at different times, for different levels of invasion, before and after water flooding, or for different saturation states. The inferred property may pertain to the oil and gas industry, material analysis, medicine, pharmaceuticals, the process industry, or the food industry. For example, the inferred property may be the porosity of a subsurface formation.

Abstract: A permanent monitoring tool is provided and disposed in a wellbore. Measurements are made at different times using the permanent monitoring tool on a region of a formation penetrated by the wellbore. One or more properties of the formation are inferred at one or more depths of investigation within the region using the measurements. Any changes in the one or more inferred formation properties are determined and one or more reservoir management decisions are made based on the determined changes. The well may be an observation well, an injector well, or a production well. The permanent monitoring tool may be a magnetic resonance tool or an electromagnetic tool. The measurements may be stacked to improve the signal-to-noise ratio of the signal. Different depths of investigation may be selected using antenna arrays of different lengths. The inferred properties may be saturation or resistivity. Conductive or non-conductive casing may be used.

Abstract: A tool having an energy source and a surface roughness measurement device is provided. A baseline measurement of surface roughness of a sample is made. The sample is then exposed to energy from the energy source, causing the temperature of the sample to increase. A second measurement of surface roughness of the sample is made. The change in surface roughness of the sample is determined. Formation properties such as the total organic carbon in the sample is inferred based on the determined change in surface roughness of the sample. The tool may be disposed in a wellbore and may use packers to isolate a portion of the wellbore, or it may use a hydraulic seal on an extendible member to isolate a sample portion of the wellbore wall. The energy source may be a laser that produces radiation that selectively heats a particular component of the sample constituent material.

Abstract: A tool having two current electrodes, three or more voltage electrodes, and a measurement device capable of making electrical measurements is provided, along with a sample. With electrical connectivity to the sample, one current electrode is disposed at one location on the sample while the other current electrode is disposed at another location on the sample, and the three or more voltage electrodes are disposed on the sample intermediate the two current electrodes. An electric current is passed through the sample. The measurement device is used to make a first set of electrical measurements that involve a first pair of voltage electrodes and to make a second set of electrical measurements that involve a second pair of voltage electrodes. The first set of electrical measurements is compared to the second set of electrical measurements. It is inferred whether the sample has heterogeneous electrical properties using the compared electrical measurements.