A method for separating oil-water two-phase NMR signals by using dynamic nuclear polarization comprising: using a combination of a non-selective free radical and a selective relaxation reagent to selectively enhance an NMR signal of an oil phase or a water phase, the relaxation reagent being capable of selectively suppressing dynamic polarization enhancement of the water phase or oil phase, thus achieving the polarization enhancement of a single fluid phase in the mixed fluid phases and realizing separation of the two-phase signals; or using a selective free radical to selectively enhance the NMR signal of the oil phase or the water phase, thus achieving the polarization enhancement of a single fluid phase in the mixed fluid phases and realizing separation of the oil-water two-phase NMR signals. The method is simple and easy to operate, has a short test time, and can efficiently separate NMR signals of oil and water phases.

A formation monitoring well system accurately measures formation electrical properties behind the casing to determine water-oil contact positions and/or to assess the integrity of the cement seal over the life of the well. The well system includes a casing string having one or more formation monitoring modules embedded therein, each having a toroid sensor.

During operation, current is provided to the casing string, and the toroid measures the current flowing into the formation. Also, the voltage drop between the sensor and an electrode positioned between the cement layer and formation may be measured. This data may then be processed to determine the resistivities of the formation and/or cement layer, whereby the cement seal quality, water-oil contact surface position, etc. may be extracted from the results.

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.

This disclosure may relate to a system and method for calculating the mud angle from a downhole device. A method for estimating a mud angle may comprise: disposing a downhole tool into a borehole; extending an arm of the downhole tool to a first location, wherein a pad is disposed on the arm; taking a first impedance measurement with at least one button electrode, wherein the button electrode is disposed in a button array, wherein the button array is disposed on the pad; extending the arm to a second location; taking a second impedance measurement with the at least one button electrode; transmitting the first measurement and the second measurement to an information handling system; and estimating the mud angle from the first impedance measurement and the second impedance measurement with an information handling system.

A system for locating water floods, in some embodiments, comprises: multiple non-reference electrodes with insulative pads for coupling to a borehole casing; a reference electrode with an insulative pad for coupling to the borehole casing; and multiple transducers coupled to the reference and non-reference electrodes, each of said electrodes coupled to one or more of the multiple transducers, wherein each transducer coupled to a non-reference electrode determines a differential non-reference potential between that non-reference electrode and the reference electrode, and wherein a transducer that couples to the borehole casing determines an absolute reference potential between the borehole casing and the reference electrode; wherein the differential non-reference potentials are mathematically combined with the absolute reference potential to produce absolute non-reference potentials; wherein scaling weights are applied to said absolute non-reference potentials to produce scaled absolute potentials that are used to determine a water flood location.

A method of determining a condition within a wellbore. The method comprises introducing a tubular member in a wellbore extending through a subterranean formation, the tubular member comprising a downhole article including a deformable material disposed around a surface of the tubular member, electrically conductive elements dispersed within the deformable material. The method includes measuring at least one electrical property of the deformable material. At least one of water ingress into the wellbore or an amount of expansion of the deformable material is determined based on the at least one measured electrical property. Related downhole systems and other related methods are also disclosed.

A k-space data acquisition device and method, and a magnetic resonance imaging device and method. The k-space data acquisition device includes an acquisition trajectory determiner configured to determine an acquisition trajectory of echo signals in a k space in a manner of filling echo data in a pseudo radial order; and a data acquirer configured to acquire k-space data conforming to the acquisition trajectory and fill the k space.

The present disclosure relates to a method for measuring a water level by using a UAV and virtual water control points and a method for generating 3D water surface spatial information, and a UAV used therefor. According to an embodiment, an UAV for a water surface survey includes: a position measurement unit configured to receive a GPS signal and to obtain position information of the UAV; a distance measurement unit including a plurality of laser measurement devices configured to project lasers toward the water surface; and a controller configured to calculate a moving distance of the UAV, based on measurement values of the position measurement unit and the distance measurement unit.

A method for sensing a condition of a hydrocarbon reservoir from a subterranean well having a lined section with a liner and an unlined section includes attaching an electric current sensor to the liner proximate to a lower end of the lined section and a plurality of electromagnetic sources located along the unlined section. The electromagnetic sources are activated independently and the resulting current induced in the liner by each electromagnetic source is measured with the electric current sensor. These measurements can be inverted to determine the spatial distribution of the electric conductivity within the reservoir and its changes in time due to fluid substitution during production. Alternatively, a fast and robust method for interpretation of the data is presented for early detection and location of a possible water front approaching the production well.