Abstract: A method includes operating a downhole acquisition tool in a wellbore in a geological formation. The wellbore or the geological formation, or both, contain a reservoir fluid. The method also includes receiving a portion of the reservoir fluid into the downhole acquisition tool and performing downhole fluid analysis using the downhole acquisition tool in the wellbore to determine at least one measurement associated with the portion of the reservoir fluid. The at least one measurement includes fluid density, optical density, or both. The method also includes using a processor of the downhole acquisition tool to obtain compressibility of the reservoir fluid based at least in part on the fluid density, the optical density, or both and determining a composition of the reservoir fluid based at least in part on the compressibility.

Abstract: A fluid sampling probe may include one or more features that increase the likelihood that a seal will be maintained during a sampling operation, even for sampling operations in unconsolidated formations. This may reduce contamination in formation fluid samples that are obtained during sampling operations. The fluid sampling probe may include a reinforcement ring configured to extend into a geological formation beyond an elastomer portion of the fluid sampling probe, which may support the geological formation and prevent a failure of the formation during sampling operations. The fluid sampling probe may also include a stop sleeve to prevent overextension that could otherwise cause the geological formation to collapse. In addition, the fluid sampling probe may include a relatively wider sealing elastomer that may decrease in height monotonically radially from the center of the fluid sampling probe.

Abstract: A formation sampling method includes disposing a downhole tool comprising a packer and an expandable probe within a wellbore. The method also includes performing pressure transient testing by setting the expandable packer and the probe to engage a wall of the wellbore and measuring a pressure response at the expandable packer and the probe while withdrawing formation fluid into the downhole tool through the expandable packer. The method further includes monitoring a contamination level of the formation fluid during the pressure transient testing, and performing formation sampling with the probe in response to determining that the monitored contamination level meets a predetermined threshold.

Abstract: The present disclosure relates to methods and apparatus for determining a viscosity-pressure profile of downhole fluid by measuring the viscosity at several different pressures during a sampling operation. According to certain embodiments, the viscosity may be measured at different times during a sampling operation and used to generate the viscosity-pressure profile. For example, the viscosity may be measured at the beginning of pumping, during filling of a sample chamber, during a pressure-build up period, and while retracting the probe. The measured viscosities may then be employed to determine a profile that represents the change in viscosity that occurs with pressure.

Abstract: A method for performing contamination monitoring through estimation wherein measured data for optical density, gas to oil ratio, mass density and composition of fluid components are used to obtain plotting data and the plotting data is extrapolated to obtain contamination levels.

Abstract: Methods and downhole tools for operation within in a wellbore that extends into a subterranean formation. The operation includes simultaneously causing a change in a first parameter of fluid drawn into the downhole tool from the formation and determining a change in a second parameter of the fluid relative to the change in the first parameter. A third parameter of the fluid is determined based on the first and second parameter changes.

Abstract: The present disclosure relates to a downhole fluid analysis method that includes withdrawing formation fluid into a downhole tool at a plurality of stations within a wellbore, analyzing the formation fluid within a fluid analyzer of a downhole tool to determine properties of the formation fluid for the plurality of stations, and developing, based on the determined properties of the formation fluid, a relationship for predicting viscosity from a measured optical density.

Abstract: Systems and methods for obtaining in-situ measurements of mixed formation fluids are provided. A downhole acquisition tool may move to a first station in a wellbore in a geological formation to collect a sample of first formation fluid from the first station. The downhole acquisition tool may move to a second station in the wellbore and a sample of second formation fluid may be collected. A proportion of the first formation fluid and the second formation fluid may be mixed within the downhole acquisition tool in-situ while the downhole acquisition tool is within the wellbore to obtain a formation fluid mixture. The formation fluid mixture may be passed into a fluid testing component of the downhole acquisition tool while the downhole acquisition tool is in the wellbore to measure fluid properties of the formation fluid mixture in-situ.

Abstract: Various implementations described herein are directed to a method for assessing risks of compartmentalization. In one implementation, the method may include receiving seismic data for a formation of interest; identifying areas in the formation having a dip angle greater than about 30 degrees; performing a plurality of downhole fluid analysis (DFA) within a wellbore around the formation having the dip angle greater than about 30 degrees to identify areas experiencing mass density inversion; and determining the areas experiencing mass density inversion by DFA as having one or more risks of compartmentalization.

Abstract: Apparatus and methods for performing downhole testing. Example apparatus include a downhole tool string for conveying within a wellbore, the downhole tool string comprising an anchor device, a testing device, and a linear or rotary actuator. The anchor device maintains a portion of the downhole tool string in a predetermined position within the wellbore. The testing device is operable to receive a downhole sample from or test a subterranean formation surrounding the wellbore. The linear actuator is connected between the anchor device and testing device, and moves the testing device relative to the anchor device.

Abstract: The present disclosure relates to systems and methods for determining an integrity of a sample chamber. In certain embodiments, formation fluid is collected from a subterranean formation within a sample chamber disposed in a downhole tool, the downhole tool is withdrawn from a wellbore, an estimated surface pressure of the collected formation fluid is determined, the estimated surface pressure of the collected formation fluid is compared with an actual surface pressure of the sample chamber, and the integrity of the sample chamber is determined based on the comparison of the estimated surface pressure and the actual surface pressure.

Abstract: The present disclosure relates to methods and apparatus for determining a viscosity-pressure profile of downhole fluid by measuring the viscosity at several different pressures during a sampling operation. According to certain embodiments, the viscosity may be measured at different times during a sampling operation and used to generate the viscosity-pressure profile. For example, the viscosity may be measured at the beginning of pumping, during filling of a sample chamber, during a pressure-build up period, and while retracting the probe. The measured viscosities may then be employed to determine a profile that represents the change in viscosity that occurs with pressure.

Abstract: The present disclosure relates to methods and apparatus for determining a viscosity-pressure profile of downhole fluid by measuring the viscosity at several different pressures during a sampling operation. According to certain embodiments, the viscosity may be measured at different times during a sampling operation and used to generate the viscosity-pressure profile. For example, the viscosity may be measured at the beginning of pumping, during filling of a sample chamber, during a pressure-build up period, and while retracting the probe. The measured viscosities may then be employed to determine a profile that represents the change in viscosity that occurs with pressure.

Abstract: Systems and methods for identifying a likelihood that a reservoir of a geological formation received a secondary charge of hydrocarbons of relatively very different thermal maturity of composition are provided. One method includes positioning a downhole acquisition tool in a wellbore in a geological formation and testing one or more fluid properties of the formation fluid. Data processing circuitry may identify whether a relationship of the one or more fluid properties exceeds a first threshold that indicates likely asphaltene instability. When this is the case, data processing circuitry may be used to model the geological formation using a realization scenario in which multiple charges of hydrocarbons of substantially different thermal maturity or substantially different composition, or both, filled a reservoir of the geological formation over geologic time.

Abstract: A method includes operating a downhole acquisition tool in a wellbore in a geological formation. The wellbore or the geological formation, or both, contain a reservoir fluid. The method also includes receiving a portion of the reservoir fluid into the downhole acquisition tool and performing downhole fluid analysis using the downhole acquisition tool in the wellbore to determine at least one measurement associated with the portion of the reservoir fluid. The at least one measurement includes fluid density, optical density, or both. The method also includes using a processor of the downhole acquisition tool to obtain compressibility of the reservoir fluid based at least in part on the fluid density, the optical density, or both and determining a composition of the reservoir fluid based at least in part on the compressibility.

Abstract: Methods for obtaining in-situ, multi-temperature measurements of fluid properties, such as saturation pressure and asphaltene onset pressure, are provided. In one example, a sample of formation fluid is obtained using a downhole acquisition tool positioned in a wellbore in a geological formation. The downhole acquisition tool may be stationed at a first depth in the wellbore that has an ambient first temperature. While stationed at the first depth, the downhole acquisition tool may test a first fluid property of the sample to obtain a first measurement point at approximately the first temperature. The downhole acquisition tool may be moved to a subsequent station at a new depth with an ambient second temperature, and another measurement point obtained at approximately the second temperature. From the measurement points, a temperature-dependent relationship of the first fluid property of the first formation fluid may be determined.

Abstract: Systems and methods for obtaining in-situ measurements of mixed formation fluids are provided. A downhole acquisition tool may move to a first station in a wellbore in a geological formation to collect a sample of first formation fluid from the first station. The downhole acquisition tool may move to a second station in the wellbore and a sample of second formation fluid may be collected. A proportion of the first formation fluid and the second formation fluid may be mixed within the downhole acquisition tool in-situ while the downhole acquisition tool is within the wellbore to obtain a formation fluid mixture. The formation fluid mixture may be passed into a fluid testing component of the downhole acquisition tool while the downhole acquisition tool is in the wellbore to measure fluid properties of the formation fluid mixture in-situ.

Abstract: The present disclosure relates to a formation sampling method that includes disposing a downhole tool comprising a packer and an expandable probe within a wellbore. The method also includes performing pressure transient testing by setting the expandable packer and the probe to engage a wall of the wellbore and measuring a pressure response at the expandable packer and the probe while withdrawing formation fluid into the downhole tool through the expandable packer. The method further includes monitoring a contamination level of the formation fluid during the pressure transient testing, and performing formation sampling with the probe in response to determining that the monitored contamination level meets a predetermined threshold.

Abstract: A method includes receiving first fluid property data from a first location in a hydrocarbon reservoir and receiving second fluid property data from a second location in the hydrocarbon reservoir. The method includes performing a plurality of realizations of models of the hydrocarbon reservoir according to a respective plurality of one or more plausible dynamic processes to generate one or more respective modeled fluid properties. The method includes selecting the one or more plausible dynamic processes based at least in part on a relationship between the first fluid property data, the second fluid property data, and the modeled fluid properties obtained from the realizations to identify potential disequilibrium in the hydrocarbon reservoir.

Abstract: The present disclosure relates to a downhole fluid analysis method that includes withdrawing formation fluid into a downhole tool at a plurality of stations within a wellbore, analyzing the formation fluid within a fluid analyzer of a downhole tool to determine properties of the formation fluid for the plurality of stations, and developing, based on the determined properties of the formation fluid, a relationship for predicting viscosity from a measured optical density.