Downhole fluid sensing device is disclosed for determining heat capacity of a formation fluid produced by a sampled subterranean well, the sensor package having an annulus shaped, elongate body defining a cylindrical fluid sampling space, the sensor package and the sampling space having a common longitudinal center axis. The elongate sensor package body has a fluid entrance port that provides well fluid ingress into the fluid sampling space and a fluid exit port that provides well fluid egress out of the fluid sampling space. A heat source is coupled to the elongate sensor package body and located along a portion of the fluid path, and the heat source inputs heat into sampled well fluid. Finally, temperature sensing devices (located between the fluid entrance port and fluid exit port measure heat conducted to the sampled well fluid, wherein each of the temperature sensing devices is radially spaced from the heat source.

A downhole well fluid sensing device is disclosed for determining thermal conductivity of a formation fluid produced by a sampled subterranean well, the sensor package having an annulus shaped, elongate body defining a cylindrical fluid sampling space, the elongate body and the sampling space having a common longitudinal center axis. The elongate body has a fluid entrance port that provides well fluid ingress into the fluid sampling space and a fluid exit port that provides well fluid egress out of the fluid sampling space. A heat source is coupled to the elongate body and located along a portion of the fluid path, and the heat source inputs heat into sampled well fluid. Finally, temperature sensing devices located between the fluid entrance port and fluid exit port measure heat conducted to the sampled well fluid, wherein each of the temperature sensing devices is radially spaced from the heat source.

Systems and methods for selecting surfactants for use in subterranean formations are provided. In one embodiment, the methods comprise: providing a sample of oil from at least a portion of a subterranean formation; measuring at least one of the total acid number (TAN) and the total base number (TBN) of the oil sample; and selecting a set of surfactants to evaluate for a treatment in at least a portion of the subterranean formation based on at least one of the TAN and the TBN of the oil sample, the set of surfactants selected from the group consisting of: a set of cationic surfactants, a set of anionic surfactants, and a set of zwitterionic surfactants.

Methods are provided for determining saturation parameters of a formation while sampling the formation. Flow rate and pressure data may be used in order to provide mobility information close to the probe. In turn, the mobility information may be used in conjunction with at least water fraction information in order to provide an estimation of saturation parameters of the formation such as maximum residual oil saturation S.sub.orm, connate water saturation S.sub.wc, and residual water saturation S.sub.wr. Resistivity measurements may be used to help in the estimation of the saturation parameters. Initial estimations may be used as the starting parameters for a full parameter inversion. An interpretation scheme in the absence of invasion details is provided.

A downhole formation fluid viscometer sensor and method therefor include a viscometer sensing package, a flexible diaphragm, a magnet and electric coil, and a signal pickup assembly. The viscometer sensor may also include a first cavity and a second cavity for mechanical and electric energy transfer. The magnet and electric coil may be driven by external alternating current to generate an electromagnetic force. Silicon oil may be used to fill the first cavity and/or a pressure balance hole may connect the first cavity to an external area. The diaphragm may be a titanium alloy and a ferromagnetic magnet may be attached to the diaphragm. The diaphragm preferably has a thickness from about 0.030 to about 0.040 inches and the magnet and electric coil can propel the diaphragm to vibrate at a frequency from 0 to 100 kHz. Formation fluid viscosity is determined using resonant frequency linewidth, with contributions from the sensor package intrinsic properties removed.

A system for increasing the detecting degradation of a wellbore. The system comprises a computer memory configured for storing computing instructions and a processor operably coupled to the computer memory. The system comprises a sensor operably coupled to the computer memory and is configured to determine the presence of at least one chemical species indicative of degradation of the wellbore in a fluid exiting the wellbore. Methods of monitoring a wellbore for corrosion or other degradation of one or more components of wellbore equipment are disclosed as are methods of increasing the lifetime of a wellbore.

A method may include collecting a sample of mud gas during a wellbore drilling operation, associating the sample with a depth of the wellbore, and detecting concentrations of methane, ethane and ethylene. With the detected concentrations, a determination can be made as to the degree of a mud gas artifact event occurring, including determining the differences between the logarithmic values of concentrations of methane and total C2 concentration and the logarithmic values of total C2 concentration and ethane. A visually displayed mud gas log is modified to indicate the degree of the determined mud gas artifact event.

Methods and systems are provided for characterizing interfacial tension (IFT) of reservoir fluids, which involves obtaining fluid property data that represents fluid properties of a reservoir fluid sample measured downhole at reservoir conditions, and inputting the fluid property data to a computational model that determines a value of oil-water IFT of the reservoir fluid sample based on the fluid property data. In embodiments, the fluid property data represents single-phase fluid properties of the reservoir fluid sample, such as fluid density and viscosity of an oil phase of the reservoir fluid sample and fluid density of a water phase of the reservoir fluid sample. In embodiments, the computation model can be based on machine learning or analytics combined with a thermodynamics-based physics model.

Examples described herein provide a downhole sampling method that includes receiving fluid data from a fluid downhole in a wellbore operation. The method further includes defining a subset of the fluid data and a remaining subset of the fluid data. The method further includes iteratively generating, by a processing device, a plurality of curves fit to the subset of the fluid data. The method further includes performing, by the processing device, a validation on the plurality of curves as applied to the remaining subset of the fluid data to determine one or more best fit curves from the plurality of curves.

In some embodiments, a method for locally lumped equation of state fluid characterization can include determining a set of components for the material balance calculations for a plurality of grid blocks of a reservoir. The plurality of grid blocks can experience different recovery methods between them. Lumping schemes can be determined for the plurality of grid blocks. Phase behavior calculations can be performed on the plurality of grid blocks, wherein different lumping schemes can be used across the plurality of grid blocks.