Abstract: A method and system may include receiving, via one or more sensors in a wellbore formed in a subsurface formation, measurements of a concentration of an interactive component and a concentration of a non-interactive component in a formation fluid from the subsurface formation, wherein the non-interactive component and the interactive component comprise a component in the formation fluid that is non-interactive and interactive, respectively, with respect to a drilling fluid. The method and system may further include determining a level of contamination from a drilling fluid filtrate that contaminates the formation fluid based on the non-interactive component concentration in the formation fluid and the interactive component concentration in the formation fluid.

Abstract: A method and system can obtain real time property measurements of a fluid comprising a formation fluid downhole, real time measurements of an amount of an interactive component of the fluid downhole, and real time measurements of an amount of a non-interactive component of the fluid downhole. The method and system further includes determining a total amount of the interactive component in the fluid or a contamination level of the formation fluid at a time of interest based on the real time property measurements of the fluid downhole and the real time measurements of the amounts of the interactive component and non-interactive component downhole. The real time measurements of the amount of the interactive component downhole are real time measurements of the amount of the interactive component in its free form downhole, and the property can be scaled with the contamination level.

Abstract: Methods and systems for determining whether a base oil for use in drilling muds will be compatible with cement during subsequent cementing operations include: providing a drilling fluid that includes a base oil; using the drilling fluid to drill at least a portion of a wellbore penetrating at least a portion of a subterranean formation; measuring a compositional characteristic of the base oil using one or more analytical tests; determining whether the base oil is a compatible base oil or an incompatible base oil based at least in part on the compositional characteristic of the base oil; injecting an amount of spacer fluid into the wellbore, wherein the amount of spacer fluid is selected based on the determination of whether the base oil is a compatible base oil or an incompatible base oil; and injecting the one or more cementing or completion fluids into the wellbore.

Abstract: This disclosure provides a method of determining a pore throat size distribution of reservoir rock, comprising injecting a set of different-sized probe particles through a portion of reservoir rock and measuring retention volumes or times of each of the different-sized probe particles eluting from the portion of reservoir rock. This disclosure also provides a testing apparatus comprising a probe tube for receiving a set of different-sized probe particles in an elution fluid returning from a portion of reservoir rock and an analytical module connected to receive the elution fluid from the probe tube.

Abstract: Systems and methods are provided for determining a presence, type, or amount of an analyte in fluid. An analyte sensor can include a substrate that includes a chiral molecule for sensing the presence of the analyte in the fluid. A property of the chiral molecule may change in response to sensing the presence of the analyte. The change in the property of the chiral molecule can cause a change in polarization of a beam of light traveling through the substrate. The presence, type, or amount of the analyte can be determined based on the change in polarization of the beam of light. The analyte sensor, along with optical fibers, can be used to determine the presence, type, or amount of an analyte in a fluid sample from a wellbore.

Abstract: Optical analysis devices may be configured for optically interacting a set cement with a chemical filter and a detector that together are configured to detect a characteristic of the set cement, wherein optically interacting the set cement with the chemical filter comprises absorbing, by the chemical filter, at least a portion of an electromagnetic radiation having optically interacted with the set cement. Relative to cementing operations, such optical analysis devices may be useful in identifying fluids, analyzing compositions of cement slurries, investigating the status of a reaction occurring in a cement slurry, detecting and/or monitoring corrosion of a set cement, and the like.

Abstract: A composition includes a borehole or pipeline fluid and a delivery molecule, the delivery molecule stable under conditions external to a borehole or pipeline and including a precursor having an end terminating in degradable linkages bonding the precursor to bridged groups and another end terminating in a leaving group, where under in situ conditions in the pipeline or downhole from the borehole surface contact with an initiator acid catalyzes degradation of the degradable linkages and elimination of the leaving group, releasing the precursor and generating an additive from the precursor. A method includes placing the delivery molecule in the borehole or pipeline; and after the placing, contacting the composition with an initiator acid under in situ conditions.

Abstract: A composition includes a borehole or pipeline fluid and a delivery molecule, the delivery molecule stable under conditions external to a borehole or pipeline and including a precursor having an end terminating in degradable linkages bonding the precursor to bridged groups and another end terminating in a leaving group, where under in situ conditions in the pipeline or downhole from the borehole surface contact with an initiator acid catalyzes degradation of the degradable linkages and elimination of the leaving group, releasing the precursor and generating an additive from the precursor. A method includes placing the delivery molecule in the borehole or pipeline; and after the placing, contacting the composition with an initiator acid under in situ conditions.

Abstract: Methods and systems for determining whether a base oil for use in drilling muds will be compatible with cement during subsequent cementing operations are provided. In some embodiments, the methods include: providing a drilling fluid that includes a base oil; using the drilling fluid to drill at least a portion of a wellbore penetrating at least a portion of a subterranean formation; measuring a compositional characteristic of the base oil using one or more analytical tests; determining whether the base oil is a compatible base oil or an incompatible base oil based at least in part on the compositional characteristic of the base oil; injecting an amount of spacer fluid into the wellbore, wherein the amount of spacer fluid is selected based on the determination of whether the base oil is a compatible base oil or an incompatible base oil; and injecting the one or more cementing or completion fluids into the wellbore.

Abstract: Systems and methods are provided for determining a presence, type, or amount of an analyte in fluid. An analyte sensor can include a substrate that includes a chiral molecule for sensing the presence of the analyte in the fluid. A property of the chiral molecule may change in response to sensing the presence of the analyte. The change in the property of the chiral molecule can cause a change in polarization of a beam of light traveling through the substrate. The presence, type, or amount of the analyte can be determined based on the change in polarization of the beam of light. The analyte sensor, along with optical fibers, can be used to determine the presence, type, or amount of an analyte in a fluid sample from a wellbore.

Abstract: A method and system can obtain real time property measurements of a fluid comprising a formation fluid downhole, real time measurements of an amount of an interactive component of the fluid downhole, and real time measurements of an amount of a non-interactive component of the fluid downhole. The method and system further includes determining a total amount of the interactive component in the fluid or a contamination level of the formation fluid at a time of interest based on the real time property measurements of the fluid downhole and the real time measurements of the amounts of the interactive component and non-interactive component downhole. The real time measurements of the amount of the interactive component downhole are real time measurements of the amount of the interactive component in its free form downhole, and the property can be scaled with the contamination level.

Abstract: Optical analysis devices may be configured for optically interacting a set cement with a chemical filter and a detector that together are configured to detect a characteristic of the set cement, wherein optically interacting the set cement with the chemical filter comprises absorbing, by the chemical filter, at least a portion of an electromagnetic radiation having optically interacted with the set cement. Relative to cementing operations, such optical analysis devices may be useful in identifying fluids, analyzing compositions of cement slurries, investigating the status of a reaction occurring in a cement slurry, detecting and/or monitoring corrosion of a set cement, and the like.

Abstract: This disclosure provides a method of determining a pore throat size distribution of reservoir rock, comprising injecting a set of different-sized probe particles through a portion of reservoir rock and measuring retention volumes or times of each of the different-sized probe particles eluting from the portion of reservoir rock. This disclosure also provides a testing apparatus comprising a probe tube for receiving a set of different-sized probe particles in an elution fluid returning from a portion of reservoir rock and an analytical module connected to receive the elution fluid from the probe tube.

Abstract: Optical analysis devices may be configured for optically interacting a material of interest with a chemical filter and a detector that together are configured to detect a characteristic of the material of interest, wherein optically interacting the material of interest with the chemical filter comprises absorbing, by the chemical filter, at least a portion of an electromagnetic radiation having optically interacted with the material of interest. Relative to cementing operations, such optical analysis devices may be useful in identifying fluids, analyzing compositions of cement slurries, investigating the status of a reaction occurring in a cement slurry, detecting and/or monitoring corrosion of a set cement, and the like.

Abstract: Optical analysis systems and methods may be used for analyzing the characteristics, including compositions, of cement additives, which may be used in formulating a cement slurry. For example, a cement additive may be optically interacting with an integrated computational element (“ICE”) configured to detect a characteristic of the cement additive. An output signal may then be generated corresponding to the characteristic of the cement additive detected by the ICE, which may be received and processed with a signal processor to yield a value for the characteristic of the cement additive. The value of the characteristic of the cement additive may then be used to determine an amount of the cement additive for use in producing a cement slurry.

Abstract: Systems and methods for measuring a characteristic of a fluid are provided. The system includes a plurality of waveguides embedded in a substrate, and an exposed surface of the substrate comprising a portion of a side surface of at least one of the plurality of waveguides. The system also includes a sensitized coating in the at least one of the plurality of waveguides. The exposed surface is curved in a direction perpendicular to a light propagation in the waveguide. A method of fabricating a system as above is also provided.

Abstract: Systems and methods for measuring a characteristic of a fluid are provided. The system includes a plurality of waveguides embedded in a substrate, and an exposed surface of the substrate comprising a portion of a side surface of at least one of the plurality of waveguides. The system also includes a sensitized coating in the at least one of the plurality of waveguides. The exposed surface is curved in a direction perpendicular to a light propagation in the waveguide. A method of fabricating a system as above is also provided.

Abstract: Optical analysis devices may be configured for optically interacting a material of interest with a chemical filter and a detector that together are configured to detect a characteristic of the material of interest, wherein optically interacting the material of interest with the chemical filter comprises absorbing, by the chemical filter, at least a portion of an electromagnetic radiation having optically interacted with the material of interest. Relative to dry cements, such optical analysis devices may be useful in classifying and/or grading dry cements and determining the composition and/or concentration of cement slurry additives to enhance the implementation efficacy of the dry cement.

Abstract: Systems and methods for measuring a characteristic of a fluid are provided. The system includes a plurality of waveguides embedded in a substrate, and an exposed surface of the substrate comprising a portion of a side surface of at least one of the plurality of waveguides. The system also includes a sensitized coating in the at least one of the plurality of waveguides. The exposed surface is curved in a direction perpendicular to a light propagation in the waveguide. A method of fabricating a system as above is also provided.

Abstract: Integrated computational elements having alternating layers of materials may be problematic to configure toward mimicking some regression vectors. Further, they sometimes may be inconvenient to use within highly confined locales. Integrated computational elements containing a quantum dot array may address these issues. Optical analysis tools with an integrated computational element can comprise: an electromagnetic radiation source that provides electromagnetic radiation to an optical pathway; an integrated computational element positioned within the optical pathway, the integrated computational element comprising a quantum dot array having a plurality of quantum dots disposed at a plurality of set array positions; and a detector that receives the electromagnetic radiation from the optical pathway after the electromagnetic radiation has optically interacted with a sample and the integrated computational element.