Abstract: A process of making observations of a subterranean reservoir penetrated by a wellbore uses distinguishable sets of tracer particles and comprises steps of: (i) delivering a plurality of sets of tracer particles to respective subterranean locations via the wellbore, the particles in each set comprising a tracer substance which distinguishes that set form the other sets; (ii) causing or allowing the tracer substances to flow out from the tracer particles whilst the particles are at the respective subterranean locations; (iii) causing or allowing production of fluid out of said reservoir via the wellbore; and (iv) detecting the presence or absence of the tracer substances in the produced fluid. The tracer substances are sufficiently distinguishable from each other to enable a tracer substance detected in the produced fluid to identify the set of tracer particles from which it has come and hence identify the location from which it has come.

Abstract: Disclosed herein is a gel comprising, polyacrylamide crosslinked with a non-metallic crosslinker, the non-metallic crosslinker comprising a polyamine. A method of making the gel and a method of using the gel are also disclosed.

Abstract: The recovery of oil from a reservoir is assisted by injecting a diluent into the reservoir formation to reduce the viscosity of the crude oil. This diluent is a mixture of a material which is an asphaltene precipitant, especially supercritical carbon dioxide, and a more polar material which comprises at least one aliphatic compound which includes at least one of a cycloaliphatic ring, an olefinic unsaturation, an ester or ether group. The inclusion of such an aliphatic compound which is more polar than the asphaltene precipitant reduces asphaltene precipitation and can enhance the efficiency of oil recovery when the precipitant is by supercritical carbon dioxide.

Abstract: The magnitude of asphaltic precipitation when injecting a viscosity reducing diluent into a reservoir formation, notably to assist oil recovery therefrom, is forecast by (i) determining a relationship between asphaltic precipitation and a solubility parameter for the diluted oil, and then (ii) utilizing that relationship to forecast the magnitude of asphaltic precipitation when injecting a predetermined viscosity reducing diluent into the formation. Making this forecast may be followed by injecting a viscosity reducing diluent into the formation to assist oil recovery. The diluent may in particular be supercritical carbon dioxide or other asphaltene precipitant mixed with a more polar material in proportions designed by forecasting asphaltic precipitation by candidate materials in possible proportions.

Abstract: Methods and apparatus that change the mobility of formation fluids using thermal and non-thermal stimulation including, an example apparatus to simultaneously provide thermal and non-thermal stimulation to change a mobility of a fluid in a subsurface formation includes one or more containers to hold one or more reactants. Additionally, the example apparatus includes a reactor to initiate a chemical reaction with at least one of the reactants. Further, the example apparatus includes an injector to inject a product of the chemical reaction into a formation. The product of the chemical reaction includes heat and a gaseous diluent to change a mobility of a fluid in a subsurface formation.

Abstract: A thickened aqueous composition is delivered to a subterranean location accessible via a wellbore by steps of i. providing a biphasic aqueous mixture comprising two aqueous solutions which, at surface temperature and pressure, are able to co-exist as separate aqueous phases in contact with each other, ii. pumping said biphasic aqueous system down the wellbore to the subterranean location, and iii. converting the biphasic mixture below ground so that its phases combine into a single aqueous phase which is more viscous than the biphasic mixture. The two phases of the aqueous biphasic mixture contain dissolved solutes which segregate between the two phases such that at least one first solute is present at a greater concentration in the first aqueous phase than in the second aqueous phase while at least one second solute is present at a greater concentration in the second aqueous phase than in the first aqueous phase.

Abstract: A process for hydraulic fracturing of a subterranean reservoir formation penetrated by a wellbore includes pumping a fracturing fluid or other aqueous fluid from the surface via the wellbore and into the reservoir. This fluid is an aqueous suspension of particles which each comprise an oilfield chemical distributed within an encapsulating matrix of water-insoluble carrier material. The encapsulating matrix is chosen so as to provide a delayed release of the oilfield chemical from the particles into surrounding fluid, such that oilfield chemical is liberated from the particles after they have entered the fracture. The encapsulating matrix may be a polymer which is at least partially amorphous, with a glass transition temperature below the reservoir temperature.

Abstract: Monitoring of a wellbore which penetrates a reservoir is carried out by providing tracer material at one or more subterranean locations within or proximate the wellbore, so that tracer may enter the flow and be present in flow from the wellbore; repeatedly taking samples from the flow from the wellbore, and analyzing the samples for the presence of tracer, in the vicinity of the wellsite. Taking samples from the flow will generally be done at the surface and may be done by automatic equipment controlled by a programmed computer. The computer may be programmed to take action, such as operating a valve within the well, in response to detection of tracer. Sampling repeatedly and analyzing on site can provide information in something close to real time and thus integrates the use of tracers into an overall process of monitoring and control.

Abstract: The magnitude of asphaltic precipitation when injecting a viscosity reducing diluent into a reservoir formation, notably to assist oil recovery therefrom, is forecast by (i) determining a relationship between asphaltic precipitation and a solubility parameter for the diluted oil, and then (ii) utilizing that relationship to forecast the magnitude of asphaltic precipitation when injecting a predetermined viscosity reducing diluent into the formation. Making this forecast may be followed by injecting a viscosity reducing diluent into the formation to assist oil recovery. The diluent may in particular be supercritical carbon dioxide or other asphaltene precipitant mixed with a more polar material in proportions designed by forecasting asphaltic precipitation by candidate materials in possible proportions.

Abstract: A sand consolidation system and a method for use of the system is provided. The consolidation system includes an emulsion having an oil phase and an aqueous phase, wherein the emulsion contains a source of insoluble silica particles and a source of calcium hydroxide, wherein the calcium hydroxide particles are present in the oil phase, and the insoluble silica particles are contained in the aqueous phase. Both types of particles must have average particle sizes which will fit into the pores of the formations.

Abstract: The recovery of oil from a reservoir is assisted by injecting a diluent into the reservoir formation to reduce the viscosity of the crude oil. This diluent is a mixture of a material which is an asphaltene precipitant, especially supercritical carbon dioxide, and a more polar material which comprises at least one aliphatic compound which includes at least one of a cycloaliphatic ring, an olefinic unsaturation, an ester or ether group. The inclusion of such an aliphatic compound which is more polar than the asphaltene precipitant reduces asphaltene precipitation and can enhance the efficiency of oil recovery when the precipitant is by supercritical carbon dioxide.

Abstract: A method and system are described in which a first composition may be delivered to a target location, which target location may include but is not limited to a location in a wellbore penetrating an earth formation. The first composition is dispersed into a second composition to form an emulsion, where the emulsion is stabilized by particles that are responsive to a magnetic field. The emulsion is used to transport the first composition to the target location where the emulsion is subjected to a magnetic field sufficient to interact with the particles and disrupt the emulsion, and thereby change the viscosity of the composition and/or release the first composition at the target location. In some aspects, the first and second composition may react together upon the release of the first composition at the target location.

Abstract: A process for hydraulic fracturing of a subterranean reservoir formation penetrated by a wellbore includes pumping a fracturing fluid or other aqueous fluid which is an aqueous suspension of particles which each comprise an oilfield chemical distributed within an encapsulating matrix of water-insoluble carrier_material from the surface via the wellbore and into the reservoir. The encapsulating matrix is chosen so as to provide a delayed release of the oilfield chemical from the particles into surrounding fluid, such that oilfield chemical is liberated from the particles after they have entered the fracture. The encapsulating matrix may be a polymer which is at least partially amorphous, with a glass transition temperature below the reservoir temperature.

Abstract: A process of making observations of a subterranean reservoir penetrated by a wellbore uses distinguishable sets of tracer particles and comprises steps of: (i) delivering a plurality of sets of tracer particles to respective subterranean locations via the wellbore, the particles in each set comprising a tracer substance which distinguishes that set form the other sets; (ii) causing or allowing the tracer substances to flow out from the tracer particles whilst the particles are at the respective subterranean locations; (iii) causing or allowing production of fluid out of said reservoir via the wellbore; and (iv) detecting the presence or absence of the tracer substances in the produced fluid. The tracer substances are sufficiently distinguishable from each other to enable a tracer substance detected in the produced fluid to identify the set of tracer particles from which it has come and hence identify the location from which it has come.

Abstract: Methods and apparatus to change the mobility of formation fluids using thermal and non-thermal stimulation are described. An example apparatus to simultaneously provide thermal and non-thermal stimulation to change a mobility of a fluid in a subsurface formation includes one or more containers to hold one or more reactants. Additionally, the example apparatus includes a reactor to initiate a chemical reaction with at least one of the reactants. Further, the example apparatus includes an injector to inject a product of the chemical reaction into a formation. The product of the chemical reaction includes heat and a gaseous diluent to change a mobility of a fluid in a subsurface formation.

Abstract: A thickened aqueous composition is delivered to a subterranean location accessible via a wellbore by steps of i. providing a biphasic aqueous mixture comprising two aqueous solutions which, at surface temperature and pressure, are able to co-exist as separate aqueous phases in contact with each other, ii. pumping said biphasic aqueous system down the wellbore to the subterranean location, and iii. converting the biphasic mixture below ground so that its phases combine into a single aqueous phase which is more viscous than the biphasic mixture. The two phases of the aqueous biphasic mixture contain dissolved solutes which segregate between the two phases such that at least one first solute is present at a greater concentration in the first aqueous phase than in the second aqueous phase while at least one second solute is present at a greater concentration in the second aqueous phase than in the first aqueous phase.

Abstract: A method for stimulation of gas production from coal seams is described using a permeability modifier, such as a coal swelling agent, injected into the coal seams via a wellbore to reduce the permeability of the coal seams prior to a fracturing treatment.

Abstract: This invention relates in general to characterizing hydrocarbon reservoirs and/or determining flow properties of fluids associated with the reservoir-including fluids introduced into the reservoir to provide for hydrocarbon extraction-using biological tags and real-time polymerase chain reactions for tag detection. In embodiments of the present invention, one or more biological tags may be added to one or more liquids associated with the hydrocarbon reservoir and subsequently one or more liquid samples may be taken from locations associated with the hydrocarbon and the presence of the one or more biological tag may be qualitatively and/or quantitatively tested for in the samples using real-time PCR.

Abstract: A reservoir treatment fluid is described being a hydrochloric acid and a compound forming a carboxylic acid within a well penetrating a subterranean reservoir.

Abstract: A sand consolidation system and a method for use of the system is provided. The consolidation system includes an emulsion having an oil phase and an aqueous phase, wherein the emulsion contains a source of insoluble silica particles and a source of calcium hydroxide, wherein the calcium hydroxide particles are present in the oil phase, and the insoluble silica particles are contained in the aqueous phase. Both types of particles must have average particle sizes which will fit into the pores of the formations.