Abstract: A non-electric down-hole formation pressure monitoring system utilizing typical down-hole chemical injection system technology as the basis for pressure data acquisition combined with surface computer integration whereby a constant and accurate picture of formation pressure variations may be obtained and recorded at minimum cost. Computer integration into the chemical injection system allows the pressure differential across the pressure balanced valve located adjacent the chemical injection orifice into the well production casing to be exploited by manipulation of the injection pump pressure thereby maintaining a constant differential pressure across the check valve providing a means for tracking the well formation pressure up or down. Pressure variations in the chemical injection capillary tube on the pump side of the remote pressure balance valve mimic formation flow characteristics which may be monitored by the computer at the surface where pump noise and plumbing noise due to vibration etc.

Abstract: The invention relates to a system and method for sensing the characteristics of a fluid in a sub-surface formation. In one embodiment, the invention relates to a sensor apparatus for sensing a chemical in a vapor emitted by a sub-surface fluid sample. In various configurations, the apparatus senses the presence and/or percentage of water, the presence of a gas, an oil/gas ratio, an aliphatic/aromatic hydrocarbon ratio, and/or the presence of corrosive or poisonous chemicals.

Abstract: Described is a downhole method and apparatus for detecting hydrogen sulphide in formation fluids produced in a hydrocarbon well. The sensor system is located within or in communication with an extraction chamber used to extract hydrogen sulphide in a gaseous state from the formation fluid and preferably equipped with renewable sensing elements.

Abstract: A portable pathogen detection system that accomplishes on-site multiplex detection of targets in biological samples. The system includes: microbead specific reagents, incubation/mixing chambers, a disposable microbead capture substrate, and an optical measurement and decoding arrangement. The basis of this system is a highly flexible Liquid Array that utilizes optically encoded microbeads as the templates for biological assays. Target biological samples are optically labeled and captured on the microbeads, which are in turn captured on an ordered array or disordered array disposable capture substrate and then optically read.

Abstract: A electronic system for tracking and monitoring articles to be subjected to a sterilization cycle is disclosed. The method uses a sterilization indicator and electronically links sterilization information with the articles subjected to the sterilization process. The indicator allows a sterilization cycle to be monitored without the need for a user to subjectively distinguish between color, quality or intensity of display patterns.

Abstract: An apparatus and method for detecting explosive-indicating compounds in subsurface soil. The apparatus has a probe with an adsorbent material on some portion of its surface that can be placed into soil beneath the ground surface, where the adsorbent material can adsorb at least one explosive-indicating compound. The apparatus additional has the capability to desorb the explosive-indicating compound through heating or solvent extraction. A diagnostic instrument attached to the probe detects the desorbed explosive-indicating compound. In the method for detecting explosive-indicating compounds in soil, the sampling probe with an adsorbent material on at least some portion of a surface of the sampling probe is inserted into the soil to contact the adsorbent material with the soil. The explosive-indicating compounds are then desorbed and transferred as either a liquid or gas sample to a diagnostic tool for analysis.

Abstract: The present invention provides novel microfluidic devices and methods that are useful for performing high-throughput screening assays. In particular, the devices and methods of the invention are useful in screening large numbers of different compounds for their effects on a variety of chemical, and preferably, biochemical systems.

Abstract: Microfluidic devices for analyzing a plurality of compounds are manufactured for performing high throughput screening assays. The methods are used to manufacture devices that screen large numbers of different compounds for their effects on a variety of chemical and biochemical systems.

Abstract: The present invention is a one-step thermal method for analyzing the acid-base content of earth samples, specifically mine overburden samples. By using a low oxygen concentration, preferably about 3%, the transition metal carbonates in the sample decomposed to produce carbon dioxide at a lower temperature than the alkaline earth metal carbonates. In contrast, alkaline earth metal carbonates decompose at approximately the same (higher) temperature regardless of the oxygen concentration. Any oxidizable sulfur forms present in the sample are also oxidized by using this oxygen concentration so that only one experiment is required to obtain the carbonate and sulfur contents of the sample.

Abstract: The invention relates to a kit for the measurement of anion, cation or zwitterion availability in a medium or for the measurement of free inorganic ions in disrupted cells from plant or animal tissue. The kit comprises ion-exchange material having a measurable ion uptake potential for immobilizing available ions from the medium on the material following contact on the material with the medium or suspension. It also comprises means to remove particulate solids from the material after having contacted the medium with the material. Preferably, the ion-exchange material is cation and/or anion-exchange material in the form of rigid or flexible films, sheets, membranes or the like. The invention also relates to a method for the on-site in situ measurement of anion and/or cation availability in a solid medium and to a method for measuring free organic ions in cells from plant or animal tissue.

Abstract: Disclosed is a diagnostic device for the colorimetric detection of an analyte in a test fluid. The device is a dry reagent layer which is overcoated with a transparent, fluid permeable membrane. The membrane is made up of a combination of a water dispersible and a water soluble polymer. The membrane may contain a surfactant and a thickener.

Abstract: The presence of hydrocarbons in water is detected by contacting a water sample with an adsorbent material to extract hydrocarbons from the water sample and then contacting the adsorbent material with a solvent for the hydrocarbons. A developer such as a miscible nonsolvent liquid is mixed into the solvent to produce a test mixture. The turbidity of the test mixture is observed to determine the presence of hydrocarbons in the water sample. The nonsolvent may contain at least 0.5% salt, e.g., at least 1%, preferably 5% salt, and an emulsifier. Turbidity may be measured quantitatively by measuring light scattered at 90.degree. to a test light beam or by visual comparison to a reference scale.

Abstract: Provided is a method for testing earth samples for contamination by organic contaminants, and particularly for aromatic compounds such as those found in diesel fuel and other heavy fuel oils, kerosene, creosote, coal oil, tars and asphalts. A drying step is provided in which a drying agent is contacted with either the earth sample or a liquid extract phase to reduce to possibility of false indications of contamination that could occur when humic material is present in the earth sample. This is particularly a problem when using relatively safe, non-toxic and inexpensive polar solvents such as isopropyl alcohol since the humic material tends to be very soluble in those solvents when water is present. Also provided is an ultraviolet spectroscopic measuring technique for obtaining an indication as to whether a liquid extract phase contains aromatic organic contaminants.

Abstract: A device for determining at least one petroleum characteristic of a geologic sediment sample placed in a boat, said device including a first heater heating said sample in a non-oxidizing atmosphere, a measuring component determining hydrocarbon-containing products released after feeding the sample into said first heater, a second subsequent heater heating said sample in an oxidizing atmosphere, a measuring component determining the amount of CO.sub.2 contained in effluents discharged from the two heaters, said CO.sub.2 measuring means include a cell for measuring continuously CO.sub.2 throughout heating of the first and second heaters and a measuring component determining the amount of CO contained in the effluents discharged from the two heaters, and thereby allowing determination of said petroleum characteristic.

Abstract: A method using concentrated aqueous solutions of sodium cobaltinitrite and a rhodamine dye is described which can be used to identify concrete that contains gels formed by the alkali-silica reaction (ASR), and to identify degraded concrete which results in a porous or semi-permeable paste due to carbonation or leaching. These solutions present little health or environmental risk, are readily applied, and rapidly discriminate between two chemically distinct gels; K-rich, Na--K--Ca--Si gels are identified by yellow staining, and alkali-poor, Ca--Si gels are identified by pink staining.

Abstract: A system for detecting organic contaminants in water supplies. A sampling unit is employed which includes a housing having at least one opening therein and a tubular member positioned within the housing having a central passageway surrounded by a side wall. The side wall is made of a composition designed to absorb the contaminants. In use, the sampling unit is immersed in a water supply. The water supply contacts the tubular member through the opening in the housing, with any contaminants being absorbed into the side wall of the tubular member. A carrier gas is then passed through the central passageway of the tubular member. The contaminants will diffuse out of the side wall and into the central passageway where they will subsequently combine with the carrier gas, thereby yielding a gaseous product. The gaseous product is then analyzed to determine the amount and type of contaminants therein.

Abstract: The presence of hydrocarbons in soil is detected by immersing a soil sample in a water-miscible solvent capable of dissolving the hydrocarbons to extract hydrocarbons from the soil into the solvent. An aqueous developer is mixed into the solvent to produce a test mixture. The turbidity of the test mixture is observed to determine the presence of hydrocarbons in the soil. The aqueous developer may contain at least 0.5% salt, e.g., at least 1%, preferably 5% salt, and an emulsifier. Turbidity may be measured quantitatively by measuring light scattered at 90.degree. to a test light beam or by visual comparison to a reference scale.

Abstract: A porous material (10) is contaminated with soil (14). Optionally, the porous material is partially shielded by an impermeable layer. The contaminated porous material is packaged and shipped to a user site. The contaminated porous material is removed from the package and placed in an automated processor containing medical equipment (22). The medical equipment and porous material are subjected to a cleaning, disinfecting, or sterilizing cycle in the processor. The cleaning process is evaluated by examining the porous material with an infrared or other electronic reader (24) to determine the presence of remaining soil which has not be removed during the cleaning, disinfecting, or sterilizing cycle.

Abstract: A method of determining a parameter of a physical model representing the electrical behavior of a composition is provided. The method comprises defining said model by a relationship between the electrical properties of the composition, a plurality of physical variables of the composition and said parameter, and measuring an electrical property of the composition. A sample which is representative for said composition is selected, and an electrical property of the sample is measured for various magnitudes of at least one of said physical variables. An incoherence function is selected, defining a difference between the measured electrical properties and the electrical properties as calculated from said relationship, said incoherence function being such that independent measurements are weighted in dependence of their accuracy. The parameter is determined by minimization of the incoherence function.

Abstract: A method for the quantitative determination of dissolved oxygen in a liquid fuel includes the steps of doping a sample of the fuel with a preselected concentration of a probe material including a luminophor which exhibits luminescence of wavelength which is quenched by oxygen dissolved in the fuel, illuminating the fuel with light from a coherent light source, such as a laser, of a wavelength which induces the luminescence in the luminophor, and thereafter measuring the change with time of the luminescence from the luminophor in the fuel and determing from the change with time of the luminescence the concentration of oxygen in the fuel.

Abstract: A water-immiscible organic fluid is tagged and identified by tagging the organic fluid with between about 0.25 and about 100 ppm of a marker compound having the formula: ##STR1## where the OH groups are either ortho or para to the diazo moieties, and the Xs are the same or different and are selected from C.sub.1 -C.sub.12 -alkyl, Cl, Br, F, NH.sub.2, CN, NO.sub.2, NH(C.sub.1-3 -alkyl) and N(C.sub.1-3 -alkyl).sub.2, and the fluid is identified by extracting the tagged fluid with an alkaline aqueous extractant having a pH above about 12 and containing, based on 100 parts by weight of said extractant, between about 10 and about 60 parts by weight of an organic cosolvent having the formula:R.sup.1 --O--R.sup.2 --NH.sub.2 (II)where R.sup.1 is C.sub.1 -C.sub.3 -alkyl, and R.sup.2 is C.sub.2 -C.sub.6 -alkylene.

Abstract: A method allowing fast assessment of at least one petroleum characteristic of geologic sediments from a sample of these sediments, said method comprising heating the sample in a non-oxidizing atmosphere, and which method comprises different temperature rise stages; determining at least three magnitudes S.sub.1r, S.sub.2a and S.sub.b representative of the quantity of hydrocarbons contained in said sample, and deducing at least one petroleum characteristic of the geologic sediment from these three magnitudes.

Abstract: The present invention relates to a method for determining at least one petroleum characteristic of a geologic sediment sample heated in a non-oxidizing atmosphere and an oxidizing atmosphere. The sample is heated to a first temperature value below 200.degree. C. for a predetermined period of time and then to a second temperature value ranging between 600 and 850.degree. C. according to a temperature gradient between 0.2.degree. C. and 50.degree. C./min. Carbon dioxide and carbon monoxide are continuously measured during the temperature stages in order to determine at least one petroleum characteristic, wherein said petroleum characteristic comprises a quantity of organic oxygen, inorganic oxygen, total organic carbon, or inorganic carbon.

Abstract: The present invention involves a unitized dry reagent test device and method for removing the interference caused by suspended particulate materials in the calorimetric determination of analytes in samples containing such materials. More specifically, the testing methodologies of the present invention comprise the use of a multilayer reagent impregnated matrix having known particulate removal characteristics attached to a test fluid impervious support means which has known light transmission characteristics. On-site or field testing of soil samples is an advantageous and representative application of the devices and methods of the present invention.

Abstract: A method of evaluating at least on type of pollution characteristic in a soil sample contaminated by hydrocarbon compounds, a method wherein the soil sample is first heated in a non-oxidizing atmosphere, then in an oxidizing atmosphere. The method comprises several temperature rise stages from which at least five quantities Q.sub.0, Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are measured, wherein the quantities represent concentrations of hydrocarbon compounds in the soil sample. At least one type of pollution characteristic of the sample is determined from quantities Q.sub.0, Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4.

Abstract: A subsurface soil contaminant identification system employs a cone penetrometer unit for continuously measuring the concentration of energetic materials in potentially contaminated soils. The sensor is rugged, reliable, and has a fast response time. The invention utilizes two pulsed, time-delayed miniature lasers. An infrared laser is used for decomposing the energetic material into NO and other products, while a visible laser operating near 452 nm is used for NO detection by (2+2) resonance-enhanced multiphoton ionization (REMPI). The system employs a fiber optic to transmit the output radiation at distances of approximately 30-50 meters, a lens assembly to focus one or both laser beams, a pair of miniature electrodes to collect the ions, a penetrometer, and data acquisition/processing equipment. A REMPI spectrum of 0.1% NO at atmospheric pressure reveals that the spectral resolution is sufficient such that characteristic spectral features of NO can be identified unequivocally.

Abstract: The presence of hydrocarbons in soil is detected by immersing a soil sample in a water-miscible solvent capable of dissolving the hydrocarbons to extract hydrocarbons from the soil into the solvent. An aqueous developer is mixed into the solvent to produce a test mixture. The turbidity of the test mixture is observed to determine the presence of hydrocarbons in the soil. The aqueous developer may contain at least 0.5% salt, e.g., at least 1%, preferably 5% salt, and an emulsifier. Turbidity may be measured quantitatively by measuring light scattered at 90.degree. to a test light beam or by visual comparison to a reference scale.

Abstract: A method using concentrated aqueous solutions of sodium cobaltinitrite and rhodamine B is described which can be used to identify concrete that contains gels formed by the alkali-silica reaction (ASR). These solutions present little health or environmental risk, are readily applied, and rapidly discriminate between two chemically distinct gels; K-rich, Na--K--Ca--Si gels are identified by yellow staining, and alkali-poor, Ca--Si gels are identified by pink staining.

Abstract: A method for determined porosity of an earth formation surrounding a borehole without prior knowledge of formation lithology. Neutron logging tools are used to measure thermal neutron porosity, epithermal neutron porosity and formation absorption cross section. Two calculating methods are used for a series of assumed porosity values to calculate matrix diffusion length. Matrix diffusion lengths calculated by the two methods are compared to find the highest assumed porosity for which the calculated diffusion lengths are substantially the same. This highest porosity value is the actual formation porosity.

Abstract: An apparatus for characterization of in-situ microbial biofilm populations in subsurface groundwater. The device permits biofilm-forming microorganisms to adhere to packing material while emplaced in a groundwater strata, so that the packing material can be later analyzed for quantity and type of microorganisms, growth rate, and nutrient requirements.

Abstract: A method of obtaining small representative solid-phase samples from a large solid-phase sample. Solid-phase material is optionally separated from any liquid-phase that may be present and is mixed. A portion of the mixed solid-phase particulate sample is selected which provides an intermediate size representative sample. After adding liquid diluent to the intermediate particulate sample in a vessel, the suspension is agitated to promote separation of small particles as may be adhering to large particles to obtain a homogeneous suspension. Agitating is preferably carried out using a magnetic stirring bar. Fractions of this homogeneous suspension are then obtained by aspirating using a pipette and transferred to test tubes which will constitute small, truly representative solid-phase particulate samples from which replicate testing can be confidently performed.

Abstract: Provided is a method for testing earth samples for contamination by organic contaminants, and particularly for aromatic compounds such as those found in diesel fuel and other heavy fuel oils, kerosene, creosote, coal oil, tars and asphalts. A drying step is provided in which a drying agent is contacted with either the earth sample or a liquid extract phase to reduce to possibility of false indications of contamination that could occur when humic material is present in the earth sample. This is particularly a problem when using relatively safe, non-toxic and inexpensive polar solvents such as isopropyl alcohol since the humic material tends to be very soluble in those solvents when water is present. Also provided is an ultraviolet spectroscopic measuring technique for obtaining an indication as to whether a liquid extract phase contains aromatic organic contaminants.

Abstract: The invention relates to a process for the chemical logging of a liquid and to an installation for performing the process. An object of the invention is to develop a process which makes it possible to carry out precise cartographies of chemical elements present in a liquid. This object is achieved with the aid of a process which includes performing a continuous sampling or removal of the liquid to be analyzed by way of a pipe moved progressively in the interior of the liquid. The pipe is provided with a pump which makes it possible to return the liquid to the surface, perform analyses on the samples and calculate for each analysis result the depth at which the sampling operation was carried out. The invention is more particularly used in boreholes, wells or oceanography.

Abstract: Steam quality is measured by mixing the steam with a small amount of surfactant to convert the steam to a stable foam, passing the stable foam through a capillary tube to determine foam quality (volume of vapor per volume of vapor and liquid) by measuring the streaming potential coupling coefficient of the foam passing through the tube, and converting foam quality (volume per volume) to steam quality (mass of vapor per mass of vapor and liquid) based upon the fluid density of the liquid-water and water-vapor phase of the steam.

Abstract: A system is provided for locating and delineating sea floor occurrences of petroleum seepage, achieved by apparatus for the detection of the resulting abnormal distribution of electrical potential within the affected sediments. The system uses an electrically insulating probe, deployed by steel cable from a ship, for the implantation of numerous electrodes within the sediment at depths between 60 cm and 5 m. Insulated conductors within the probe connect the electrodes to a reference electrode by way of an electrometer which facilitates measurement of the difference in electrical potential between any one of the probe electrodes and the reference electrode. Digital measurements are conducted to an associated acoustic modem and thence to the ship through the water. The system allows rapid assessments of sedimentary electrical conditions over large areas of seafloor by the repeated introduction, utilization, withdrawal, and relocation of the probe.

Abstract: A method for compensating toxicity test data for the measured toxicity of a reference sample by the steps of:a. obtaining toxic response data for a plurality of concentrations of at least two different test samples, including reagent controls having zero sample concentration for each sample;b. defining the sample having the smallest toxic response at high concentrations as the reference sample;c. computing the toxic response of the test sample relative to that for the reference sample for at least two concentrations in accordance with the equation:relative gamma=.GAMMA..sub.R =(L.sub.SC /L.sub.SX)(L.sub.RX /L.sub.RC)-1, where L.sub.SC =light output of the test sample control (i.e. for X=0),L.sub.SX =light output of the test sample for concentration X,L.sub.RX =light output of the reference sample for concentration X,L.sub.RC =light output of the reference sample control (i.e. for X=0); andd. generating a dose-response curve of concentration versus relative .GAMMA.

Abstract: An in-hole oil-drilling probe is mountable in a drill string to measure hydrocarbon concentrations in drilling fluid flowing around the drill string. The probe consists of a drill collar which is mountable in the drill string. A solvent, in which hydrocarbons are soluble, circulates within the drill collar through a hydrocarbon detection chamber. A membrane in the drill collar has an outer surface positioned to contact flowing drilling fluid and an inner surface positioned to contact circulating solvent within the drill collar. The membrane allows hydrocarbons to permeate from the drilling fluid into the solvent and into the hydrocarbon detection chamber with the solvent. A radiant energy source directs radiant ultra-violet energy into the hydrocarbon detection chamber. A sensor apparatus measures fluorescent energy radiating from the hydrocarbon detection chamber to determine solvent hydrocarbon concentration.

Abstract: A tool for measuring the mechanical properties of a formation through which a borehole has been drilled, comprising a tool body capable of being lowered into a borehole, the tool body having pads mounted on movable arms, each pad carrying a PDC type cutter which is urged against wall of the borehole so as to cut into the formation; transducers are provided for determining the depth of cut made by the cutter and for determining the resistance of the rock to cutting. The tool is connected to a wireline, enabling the cutter to be moved through the formation and the data from the transducers to be returned to the surface for analysing the depth of cut and resistance to cutting to determine the mechanical properties of the rock.

Abstract: A method assures the quantitative or semiquantitative assessment of analytes in soils by in situ optical methods. A determination is made of the optical chemical response factors for chemicals of interest which are added in known amounts to discrete soil matrices (types) and conditions (moisture content) under controlled laboratory conditions to provide predetermined reference signals. A combination probe is provided with an optical chemical sensing device that produces chemical concentration signals representative of the concentration of a chemical of interest in a soil sample and further is provided with a strain gauge sensing device that produces strain gauge signals representative of soil type and optionally, condition of the soil sample. The combination probe is inserted into the soil sample and the optical chemical sensing device produces the chemical concentration signals and the optical strain gauge sensing device, simultaneously and in parallel, produces the optical strain gauge signals.

Abstract: A method for determining residual oil saturation of a watered-out reservoir using two water soluble tracers having different partition coefficients in oil. The partitioning tracers are selected from the group consisting of tritiated or carbon 14 tagged alcohols, ketones, aldehydes, water and oil insoluble inorganics and organic radioactive isotopes. The tracers are injected into the formation, and their production curves are analyzed over a period of time to determine chromatographic separation of the tracers.

Abstract: A reagent carrying tape is captured between the soil and the outer wall of penetrometer. As the penetrometer moves with respect to the soil, the tape is pressed against an optical window in the penetrometer. Contaminants in the soil reacting with the reagents cause an optically sensible reaction in the tape to occur which is optically detected at the optical port as the penetrometer moves with respect to the tape and the soil sample. The optically sensible reaction occurring in the tape is optically isolated from the masking effects of the soil. A method is also disclosed.

Abstract: An apparatus for detecting oil and other lighter-than-water contaminants in an effluent stream in a sewage system. The apparatus includes a disposable detector which floats in the effluent stream and detects oil and other contaminants having a specific gravity lighter than the water by absorbing the oil and such contaminants in an oleophilic material, permitting the oil and other contaminants to rise and collect in a collection tube. The acidity of pH of the effluent being monitored is determined by routing a portion of the effluent stream across a litmus paper.

Abstract: An apparatus for detecting oil and other lighter-than-water contaminants in an effluent stream in a sewage system. The apparatus includes a disposable detector which floats in the effluent stream and detects oil and other contaminants having a specific gravity lighter than the water by absorbing the oil and such contaminants in an oleophilic material, permitting the oil and other contaminants to rise and collect in a collection tube. The acidity or pH of the effluent being monitored is determined by routing a portion of the effluent stream through the lower side of the detector across a litmus paper. The detector is held in the sewage system by a securing system which indicates whether the detector has been tampered with since it was installed.

Abstract: The invention relates to a device for the sampling of liquids which permeate dialysis membranes, comprising cells bounded by two such membranes. The device according to the invention is suited for determining hydrochemical profiles of groundwater, in lakes and the like. The device according to the invention is a modular one, comprising a plurality of consecutive dialysis cells, spaced at predetermined intervals, in a support system. The sampler is introduced into the liquid and left there for an adequate period of time to establish an equilibrium. After removal, each of the cells is analysed and provides information on the composition of the liquid at the given depth.

Abstract: A cylinder is mounted to descend a borehole for purposes of measuring the mass flow rate of gas flowing upward in the borehole. Within the cylinder is a source of tracer gas which is ejected at a constant mass flow rate [05] from near the lower end of the cylinder. A tracer gas concentration measuring means near the top of the cylinder will measure the degree of concentration of the tracer gas and thereby provide a measurement of the mass flow rate of other gases flowing upwardly around the cylinder.

Abstract: A method and apparatus are described for logging an open hole well, or the like, for the purpose of determining the presence of a given constituent in the various substrata and for providing means and method for determining the degree of presence of the constituent in a given formation where it has been located. A probe capable of being lowered into a bore hole includes a color video camera, a particular form of light source, apparatus for carrying and issuing a spray of cleaning substance and apparatus for carrying and issuing a chemical which facilitates the analysis of the degree of presence of the constituent. The probe is lowered to the bottom of the bore hole and then raised to a desired level. A cleaning jet sprays the surface to be inspected. The cleaned surface is then illustrated with light having a frequency in a predetermined frequency range and the reflected light is directed to the camera. The video signal is conducted to the surface where it is displayed.

Abstract: A process for in situ simulation of diagenetic processes in a subterranean formation is provided. A mineral substrate is placed in the formation of interest in a sealed vessel. The vessel is opened so as to expose the mineral substrate to formation fluids. After sufficient time for the formation fluids to act upon the mineral substrate, the substrate is removed from the formation and is examined for physical and chemical effects indicative of porosity changes in the formation.

Abstract: Residual oil saturation is determined by injecting water containing or contacting dissolved halocarboxylic acid salt and carbonate salt into an oil and water containing reservoir and chromatographically analyzing the patterns of the concentrations of in situ generated CO.sub.2 and water soluble acid salt in fluid produced from the reservoir.

Abstract: This invention provides an understanding of the structure and porosity of soil and stony regions. The method is characterized by release of a measuring gas in the region being investigated and its penetration through the investigated region to several places where it is captured and measured. Thus, the measured data from the various measuring locations provides the structure and the porosity of the region being investigated. The method is especially suited for the investigation of dams and the location of underground cavities and tectonic faults.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of particles comprising kerogen and various inorganic carbonates. A processing zone is established in the fragmented mass of formation particles and advanced therethrough. Off-gas, including carbon dioxide from carbonate decomposition, is withdrawn from the retort. The carbon dioxide content of the withdrawn off-gas, being a function of the processing zone temperature, is then determined. The determined carbon dioxide content of the withdrawn off-gas is then compared to values of carbon dioxide content of off-gas predicted as a function of processing zone temperature.