Abstract: A system for drilling a wellbore is disclosed. The injection pump releases the taggant into the mud stream traveling downhole. The taggant attaches to the rock cuttings and it is detected on the surface by the taggant detector. The taggant detector provides the data relating to the taggants detected in the drilling fluid. The data is analyzed by taggant analysis and control engine, which produces an injection profile. Based on the injection profile, the IoT Controller adapts the parameters of the taggant injection pump to achieve a real-time optimization of the taggant injection.

Abstract: A method includes introducing into a drilling fluid a plurality of tags having a first clay nanoparticle and a first polymer embedded into the clay nanoparticle and circulating the drilling fluid and tags through a well during a drilling operation that creates formation cuttings such that the tags interact with the formation cuttings, creating tagged cuttings. The returned cuttings are collected from the circulating drilling fluid at a surface of the well, and the tags on the returned cuttings are detected to identify the tagged cuttings. The method also includes correlating the tagged cuttings with a drill depth in the well from the drilling operation.

Abstract: A downhole rock debris extraction system is provided. The downhole rock debris extraction system includes a downhole marking component, a ground control component and a ground detection and extraction component. The downhole marking component is arranged at a drill bit for underground excavation or near the drill bit, and is configured to mark rock debris by spraying different types of markers in real time during the underground excavation performed by the drill bit; the ground detection and extraction component is configured to detect the types of the markers on the rock debris; and the ground control component is configured to manage and control the downhole marking component to mark the rock debris, and to manage and control the ground detection and extraction component to determine the types of the markers on the rock debris. Furthermore, a control method for the downhole rock debris extraction system is provided.

Abstract: Embodiments relate to polycrystalline diamond compacts (“PDCs”), methods of fabricating PDCs, and applications for such PDCs. In an embodiment, a method includes providing an at least partially leached polycrystalline diamond (“PCD”) body. A residual amount of acid may remain in and/or on the at least partially leached PCD body. The method further includes removing and/or neutralizing at least some of the residual amount of acid from the at least partially leached PCD body and/or a substrate to which the at least partially leached PCD body is attached.

Abstract: A method of monitoring a subterranean operation includes sampling fluid from a borehole during the operation, and estimating, in near real time, a concentration of one or more gases in the sampled fluid and an isotope composition of the sampled fluid. The method also includes identifying an operational inefficiency in the operation based on the isotope composition associated with the one or more gases, and performing, during the operation, at least one of: alerting an operator and adjusting an operational parameter of the operation, based on identifying the operational inefficiency.

Abstract: A method of mud logging is disclosed which the chemical constituents and concentrations of formation fluid are calculated based on pulse power plasma parameters and the constituent species and concentrations of drilling mud, including reaction products, upon which the pulse power plasma has acted. Based on correlation between pulse power plasma parameters, including drilling parameters, drilling can be optimized for identified formation and formation fluid species. An offset between the chemical makeup of the drilling mud exposed to pules power plasma and the chemical makeup of formation fluid is calculated. Based on the calculated offset, pulse power plasma drilling can be controlled as a function of drilling mud concentration including in other wellbores in the formation or field.

Abstract: Method for determining an extraction efficiency of at least one volatile species contained in a drilling mud, the method including: housing a test mud in a first closed container; determining a test parameter representative of a ratio between a first portion of at least one first volatile species, which is absorbed by the test mud, and a second portion of the first volatile species, which is not absorbed by the test mud, the second portion of the first volatile species being measured in a headspace of the first closed container; housing a drilling mud in a second closed container, the drilling mud containing at least one second volatile species, the second volatile species being substantially the same as the first volatile species; determining an operating parameter representative of a quantity of the second volatile species released by the drilling mud in the second closed container, wherein the quantity of the second volatile species is measured in a headspace of the second closed container; determining, as

Abstract: Methods and apparatuses, including computer program products, are described for measuring greenhouse gas. A calibration device receives a first sample of atmospheric gas from a first port exposed to the earth's atmosphere. The calibration device receives a second sample of atmospheric gas from a second port exposed to the earth's atmosphere. The calibration device routes the first sample and the second sample to a measurement device for greenhouse gas analysis. The measurement device determines a characteristic of a greenhouse gas present in at least one of the first sample and the second sample. The measurement device transmits data associated with the determined characteristic of the greenhouse gas to a computing device for determining sinks and sources of the gas.

Abstract: Methods and systems for generating intervention programs for a downhole formation including collecting mud-logging data during a drilling operation, wherein the drilling operation forms a borehole through the formation, generating zone characterization of one or more zones along the borehole based on the collected mud-logging data, defining targeted zones of the one or more zones along the borehole, generating a treatment characterization for each targeted zone based on the collected mud-logging data, and generating an intervention treatment design based on the targeted zones and associated treatment characterizations.

Abstract: A system and method calibrate efficiency of a gas extraction system in extracting hydrocarbons from mud flowing in a drilling operation. A background reading of a hydrocarbon is extracted from the mud flowing in the drilling operation with the gas extraction system and is checked for stability. An injection operation injects a known concentration of the hydrocarbon into mud, and a subject reading of the hydrocarbon is obtained with the gas extraction system during the injection operation. A correction factor of the hydrocarbon is determined for the gas extraction system by comparing the subject reading against its corresponding known concentration. Then, at least one operational reading of the hydrocarbon extracted from the mud with the gas extraction system can be corrected using the determined correction factor.

Abstract: A method for evaluating a formation fluid includes the steps of drilling a borehole intersecting a formation with a drill string, circulating a drilling fluid in the wellbore, selectively liberating a formation fluid from the formation, injecting the liberated fluid into the drilling fluid returning to the surface, drawing a sample of the returning drilling fluid at the surface, and estimating at least one parameter of the drawn sample at the surface.

Abstract: In order to predict properties of a formation in a near-wellbore area exposed to a drilling mud rheological properties of the drilling mud, of a filtrate of the drilling mud and of a reservoir fluid are determined. Properties of an external mudcake, porosity and permeability of the core sample are determined. A mathematical model of the external mudcake is created. The drilling mud is injected through a core sample and dynamics of pressure drop across the sample and dynamics of a flow rate of a liquid leaving the sample are determined. Using an X-ray micro Computed Tomography a profile of concentration of particles of the drilling mud penetrated into the sample is determined. A mathematical model is developed for the internal mudcake to describe dynamics of changes in concentration of the particles of the drilling mud in a pore space of the core sample.

Abstract: A gas analyzer system that can detect atmospheric air gasses in drilling mud is used to calculate an actual lag time in a well. The calculated lag time and a theoretical lag time may be compared to estimate a caving percentage in an open hole section of the well.

Abstract: An accessory for a device includes an actuator that is configured to be activated to operate a switch on the device when the accessory is physically engaged with the device. The switch is operable to cause the device to switch between on and off modes in which the device is configured to function. The off mode is a mode in which the device consumes less energy than when in the on mode. A controller is communicatively coupled with the actuator and is configured to activate the actuator to operate the switch when power is applied to the actuator.

Abstract: Downhole abrading tools have one or more identification tags disposed in or on the cutting end of the tools, and a housing having a detector and a relay module. The identification tags emit one or more signals that are detected by the detector which is disposed in close proximity to the cutting end. The relay module is operatively associated with the detector. During operation of the tool, the cutting end is worn causing release or destruction of one or more identification tags. The release or destruction of one or more identification tags causes a change in the signal or signals being detected by the detector. The signal change(s) is/are communicated through the relay module to the operator so that the operator can identify in real-time the amount of wear of the cutting end and, in some embodiments, the location of the wear of the cutting end.

Abstract: Presented are methods and systems for tracking and assessing drilling fluid flow and performance and, accordingly, detecting drilling mud return depth. The drilling mud is injected with a mineralogical dopant in an amount that does not affect the physical or chemical properties of the drilling mud. The doped drilling mud is injected into a known mud pulse and a detector identifies the mud pulse in which the mineralogical dopant emerges from the borehole, allowing calculation of the drilling mud return depth.

Abstract: A method of detecting changes in return drilling fluid flow during drilling operations includes injecting at least one tracer gas at a measured rate into a return drilling fluid. A first sample of gases are extracted from the return drilling fluid at a location downstream of injection of the at least one tracer gas. A first concentration of the tracer gas in the first sample of gases is measured. A second sample of gases is extracted from the return drilling fluid at the location. A second concentration of the tracer gas in the second sample is measured. Changes in measured concentration of the tracer gas from the first and second samples are determined. The method includes using the change in measured concentration to infer a change in the flow rate.

Abstract: A method of monitoring the wear of drill bits for drilling wells in earth formations, several embodiments of an improved drill bit for drilling a well in an earth formation, and methods of manufacture. In one embodiment, the bit is assembled by forming the bit, including a bit body and a plurality of cutting components; introducing a wear detector into the bit; and providing a module to monitor the wear detector and generate an indication of bit wear. The wear detector may be a witness material that may change a characteristic of at least a portion of the bit. The module may detect when the witness material is separated from the bit. The wear detector may be introduced during or after formation of the bit. The bit wear may be displayed for an operator.

Abstract: Method comprising the steps of obtaining a sample of a return drilling fluid, the return drilling fluid containing a tagged detectable additive, the tagged detectable additive comprising a polymer comprising at least one chemical tag bonded to the polymer; and determining a concentration of the tagged detectable additive in the return drilling fluid based on a spectroscopic signal of the sample. The tagged detectable additive may include a polymer comprising at least one chemical tag bonded to the polymer.

Abstract: A method for estimating a depth from which cuttings have been recovered from a well may include varying a parameter of one or more marking agents added into a drilling fluid circulated into the well and recovering the cuttings from the well. The depth may be estimated by estimating a value associated with the marking agent that marks the cuttings. A system for estimating a depth from which cuttings have been recovered from a well includes at least one marking agent configured to mark the cuttings and a marking agent dispensing device configured to add the at least one marking agent into a drilling fluid circulated into the well. The marking agent dispensing device may be further configured to vary a parameter of the at least one marking agent.

Abstract: A system and method for releasing a marker within a wellbore. The system and method includes a sensor that detects movement or a position of the marker within the wellbore. The marker may be released in drilling fluid, for example, and may travel from the surface to the drill bit and return to the surface with cuttings. As an example, the markers are used to determine the flow of cuttings within the wellbore.

Abstract: A method of monitoring the wear of drill bits for drilling wells in earth formations, several embodiments of an improved drill bit for drilling a well in an earth formation, and methods of manufacture. In one embodiment, the bit is assembled by forming the bit, including a bit body and a plurality of cutting components; introducing a wear detector into the bit; and providing a module to monitor the wear detector and generate an indication of bit wear. The wear detector may be a witness material that may change a characteristic of at least a portion of the bit. The module may detect when the witness material is separated from the bit. The wear detector may be introduced during or after formation of the bit. The bit wear may be displayed for an operator.

Abstract: The present invention relates to a process and related apparatus for determining the presence and/or quantity of H2S in the drilling debris of a subsoil layer comprising the following working steps: recovering the drilling debris of a layer; degassing the drilling debris from the previous recovery step, and separating a gaseous phase from said debris; clearing the gas released in the step of degassing, and conveying towards an H2S detector; determining the possible presence and/or quantity of H2S in the gaseous phase from the steps of degassing and clearing by means of a suitable means of detection; possible repetition of the previous phases at two layers, at least of the subsoil at different levels of depth in relation to the surface, with consequent determination of a distribution profile of H2S in the subsoil.

Abstract: A system and method for releasing a marker within a wellbore is provided. The system and method includes a sensor that detects movement or a position of the marker within the wellbore. The marker may be released in drilling fluid, for example, and may travel from the surface to the drill bit and return to the surface with cuttings. As an example, the markers are used to determine the flow of cuttings within the wellbore.

Abstract: Downhole systems and methods including tags configured to provide distinguishable identifiers are set for selective release to a subsurface location. Sources/sensors in the wellbore are activated to detect the tags at a subsurface location, and signal data associated with the detected tags is conveyed to the surface.

Abstract: A downhole abrading tools has a body with a first end for connection with a rotating component of a drill string, and a cutting end for rotation in unison with the body, the cutting end having an abrading matrix containing an abrasive material for rotating engagement with an object within the well. The downhole abrading tool also includes a passage through the tool for circulating a drilling fluid. The abrading matrix includes at least one taggant embedded within the abrading matrix capable of being released by the abrading matrix into the downhole location due to wear on the abrasive material and transported to the surface location along with the drilling fluid for detection. When the taggant is released due to excessive wear, the taggant is carried from the downhole location in the well to the surface of the well where it can be detected by the operator of the tool.

Abstract: A downhole abrading tools has a body with a first end for connection with a rotating component of a drill string and a cutting end for rotation in unison with the body. The downhole abrading tool also includes a passage through the tool for circulating a drilling fluid. Disposed within the drilling fluid passageway is a taggant injection assembly having one or more taggants disposed therein that facilitates injection of taggants into the drilling fluid upon the cutting end experience excessive wear. The taggants are then transported to the surface location along with the drilling fluid for detection by the operator of the downhole abrading tool.

Abstract: A method for determining a property of formations surrounding an earth borehole being drilled with a drill bit at the end of a drill string, using drilling fluid that flows downward through the drill string, exits through the drill bit, and returns toward the earth's surface in the annulus between the drill string and the periphery of the borehole, including the following steps: obtaining, downhole near the drill bit, a pre-bit sample of the mud in the drill string as it approaches the drill bit; obtaining, downhole near the drill bit, a post-bit sample of the mud in the annulus, entrained with drilled earth formation, after its egression from the drill bit; implementing pre-bit measurements on the pre-bit sample; implementing post-bit measurements on the post-bit sample; and determining a property of the formations from the post-bit measurements and the pre-bit measurements.

Abstract: A downhole abrading tools has a body with a first end for connection with a rotating component of a drill string, and a cutting end for rotation in unison with the body, the cutting end having an abrading matrix containing an abrasive material for rotating engagement with an object within the well. The downhole abrading tool also includes a passage through the tool for circulating a drilling fluid. The abrading matrix includes at least one taggant embedded within the abrading matrix capable of being released by the abrading matrix into the downhole location due to wear on the abrasive material and transported to the surface location along with the drilling fluid for detection. When the taggant is released due to excessive wear, the taggant is carried from the downhole location in the well to the surface of the well where it can be detected by the operator of the tool.

Abstract: The extent of invasion of a water-based drilling fluid into a formation may be determined using at least two tracers where one is deuterium oxide and the other is a water-soluble tracer. One such method includes introducing a drilling fluid having an aqueous phase and known concentrations of a water-soluble tracer and deuterium oxide into a well drilled into a fluid-producing formation; obtaining a sample of the fluid from the fluid-producing formation at a location adjacent to the well; determining the concentrations of the deuterium oxide and water-soluble tracer in the sample; and calculating the deuterium oxide concentration within the fluid producing formation based on the known and determined concentrations of the water-soluble tracer and deuterium oxide in the drilling fluid and in the sample.

Abstract: A downhole abrading tools has a body with a first end for connection with a rotating component of a drill string, and a cutting end for rotation in unison with the body, the cutting end having an abrading matrix containing an abrasive material for rotating engagement with an object within the well. The downhole abrading tool also includes a passage through the tool for circulating a drilling fluid. The abrading matrix includes at least one taggant embedded within the abrading matrix capable of being released by the abrading matrix into the downhole location due to wear on the abrasive material and transported to the surface location along with the drilling fluid for detection. When the taggant is released due to excessive wear, the taggant is carried from the downhole location in the well to the surface of the well where it can be detected by the operator of the tool.

Abstract: A downhole abrading tools has a body with a first end for connection with a rotating component of a drill string and a cutting end for rotation in unison with the body. The downhole abrading tool also includes a passage through the tool for circulating a drilling fluid. Disposed within the drilling fluid passageway is a taggant injection assembly having one or more taggants disposed therein that facilitates injection of taggants into the drilling fluid upon the cutting end experience excessive wear. The taggants are then transported to the surface location along with the drilling fluid for detection by the operator of the downhole abrading tool.

Abstract: Improved well fluids that include hollow particles, and methods of using such improved well fluids in subterranean cementing operations are provided. Also provided are methods of cementing, methods of reducing annular pressure, and well fluid compositions. While the compositions and methods of the present invention are useful in a variety of subterranean applications, they may be particularly useful in deepwater offshore cementing operations.

Abstract: The present invention provides a method and apparatus for generating one or more than one physically detectable physical influence changes to control or manipulate a down hole device. The present invention intercepts existing control signals to various controllers on the rig and superimposes an encoded command on these existing control signals. The controllers comprise of motor drives, choke controllers, acoustic pulse generators, tracer injectors and other controllers that are used to generate a physically detectable changes in the rig environment. The encoded command acting on existing or new controllers generates a perceptible change in a physical parameter such as a variation in drilling mud pressure, a variation in drill string rotation speed, a variation is weight on bit, generation of acoustic pulse, or a variation in tracer injection properties.

Abstract: A method of detecting a non-fixed object created during hole drilling operations on a system (12) includes applying a light emitting lubricant (25) to a drill bit (37) of a hole-drilling device (31). The light emitting lubricant adheres to foreign object debris 10 that is created during the hole drilling operations. The foreign object debris 10 can include shavings (29), portions of the drill bit (37), or the entire drill bit (37). The objects are illuminated with an object illuminator (16). At least one of the objects (10) is determined to be a nonmember within a known pattern of objects and is identified to be a non-fixed object in response to illumination of the objects.

Abstract: A system for driving a large diameter caisson into the ground, comprising a crane assembly, a plurality of vibratory devices, a clamp assembly, a suspension assembly, and a timing system. Each vibratory device generates a vibratory force. The clamp assembly rigidly secures each of the vibratory devices to one of a plurality of predetermined angularly spaced locations about the caisson. The suspension assembly connects the vibratory devices to the crane assembly such that transmission of vibratory forces from the vibratory devices to the crane assembly is inhibited. The timing system operatively connects the plurality of vibratory devices to synchronize the vibratory forces generated thereby.

Abstract: Compositions and methods for determining the source of treatment fluids being produced from a production formation having multiple zones by introducing a treatment composition having a tracking material into a zone in the subterranean formation, and detecting the tracking material in treatment composition that flows back from the subterranean formation.

Abstract: Disclosed is a method of determining the extent of recovery of materials injected into a oil well comprising the steps of: a) preparing a material to be injected into an oil well; b) admixing therewith a chemical tracer compound at a predetermined concentration; c) injecting the admixture into an oil well; d) recovering from the oil well a production fluid; e) analyzing the production fluid for the concentration of the chemical tracer present in the production fluid; and f) calculating the amount of admixture recovered from the oil well using the concentration of the chemical tracer present in the production fluid as a basis for the calculation. Fluorinated benzoic acids are disclosed as a preferred tracer.

Abstract: An electrically conductive oil mud meeting the fluid requirements for resistive logging tools and a method for preparing such mud is disclosed. The fluid has been optimized to deliver performance in a manner as similar to that of a traditional invert emulsion drilling fluid as is practical while still maintaining the required electrical conductivity for resistivity-based logging tools. This electrically conductive oil-based mud comprises a polar synthetic ester base and complimentary ester surfactants, one being more oil soluble, the other being more water soluble. The surfactants interact synergistically to provide dense packing of micelles at the palisade layer. This fluid is oil-wetting to solids, and in general behaves like a traditional oil mud.

Abstract: A gas analyzer for an oil drilling rig normally flows gas captured from a mud pit source through parallel paths from the gas source to a total gas analyzer. One of the paths is a loop path. Periodically the loop path is switched from the source to the total gas analyzer and connected to a path from an air supply to a chromatograph. After a short time during which the gas from the loop path is transferred to the chromatograph then the loop path is switched back to the original parallel path. This arrangement permits a small instrument to perform both the functions of total gas analyzer and chromatograph.

Abstract: The invention provides a warning to the excavation above a pipe, conduit or cable laid underground by a service utility by the directional drilling method by providing a coloured area of drilling mud and/or soil about the pipe, conduit or cable. A colouring material is added to the drill fluid during the direct drilling operation which then colours the drill mud and/or soil about the pipe, conduit or cable.

Abstract: In a well drilling operation (10), drilling fluid (70) is used to remove rock cuttings (68) and associated formation fluids released by the drill bit (84) and transport them to the surface. At the surface, a portion of these cuttings and fluids is extracted from the drilling fluid (70) for analyses. The resulting data are used in formation evaluation. This method shows how to determine the concentrations of specific formation fluids in the drilling fluid by adding and maintaining a select foreign substance of controlled concentration to the drilling fluid as a reference fluid (64), and factoring the returned formation fluids by the reference fluid. The method also shows how the technique is used as a means to assure quality control of the measuring system and as a non-disruptive means to measure lag.

Abstract: In the rotary drilling of oil wells a drilling mud is used both to transport the cuttings up to the surface and to impose an hydrostatic pressure on the walls of the borehole. For these functions the mud must for example have an acceptable viscosity and density. It is therefore important to monitor the characteristics of the mud, and to keep them within certain limits. Only recently, however, has drilling practice recognized the importance of monitoring the mud's ionic composition. The various techniques proposed involve separation of the mud into liquid and solid portions, and analysis of these. Though they have proven useful, yet there are a number of problems. For example, the separation has not always been easy, and the available techniques often may not satisfactorily remove the fines.

Abstract: A method of determining the invasion of drilling mud filtrate into a core sample from a borehole in a subterranean rock formation, comprising using a drilling mud which forms a filter cake during coring of the borehole thereby to limit invasion of drilling mud solids into the subterranean rock to an extent less than invasion of the base fluid in which the mud solids otherwise are normally suspended, dissolving a dopant in the base fluid of the drilling mud to form a solution having an X-ray attenuation characteristic different from the X-ray attenuation characteristic of the connate fluids in the subterranean formation, obtaining a core sample from the borehole using the doped drilling mud with the dopant remaining in solution in the base fluid under subterranean conditions at the core sample depth, scanning the core sample with a computed tomography scanner to determine the attenuation characteristics at a plurality of points in a cross-section in the core sample, and determining from the attenuation charact

Abstract: A method of determining dilution of a well bore fluid, such as a drilling fluid, comprising preparing a drilling fluid having a known concentration of bromide ion, using the drilling fluid, recovering a sample of the used drilling fluid, determining quantitatively the concentration of bromide ion in the used drilling fluid, comparing the concentration of bromide ion in the sample drilling fluid with the known concentration of bromide ion in the drilling fluid and determining the dilution of the drilling fluid.

Abstract: The invention in one aspect provides a method of testing drilling mud in use which comprises periodically sampling the circulating mud and analyzing its aqueous filtrate at the rig site by ion chromatography for selected positive and negative ions; one or more other parameters of the sampled mud and/or mud filtrate (e.g. pH, temperature) may also be measured; preferably the composition of the mud filtrate thus monitored is interpreted to indicate downhole interactions, with the composition of the mud supplied to the hole being adjusted to or towards the optimum as drilling proceeds. The invention also provides a method in which the solids of the periodically sampled mud are analyzed at the rig site, e.g. for sorbed ions and/or for cation exchange capacity; the values so obtained are preferably combined with those for the mud filtrate analysis and used in the diagnosis of downhole conditions for adjustment of the composition of freshly supplied mud.

Abstract: For monitoring drilling mud circulation there is incorporated in the supply mud a known amount or concentration of at least one tracer ion which is substantially non-interactive with the other mud components and with the strata drilled, and the return or circulatory mud is analyzed at the rig site (preferably by ion chromatography) for the non-interactive ion(s) to give an indication or annular dispersion. Preferably at least two tracer ions (e.g. a tracer compound providing a non-interactive cation and non-interactive anion) are used, these being analyzed independently in the return or circulatory mud to give separate checks on annular dispersion. Preferably the tracer is injected discontinuously into the supply mud, in spaced discrete relatively concentrated doses, and the residence time distribution of the tracer is plotted for each dose.

Abstract: Lag-determining method and apparatus which provides for determination of and an indication of when borehole cuttings from preselected depths arrive at the surface of the earth is disclosed and includes devices for inputting the value of the lag strokes and the predetermined drilling depth increments. A signal representative of the actual drilling depth is provided to a computer circuitry. Counter circuitry accumulates a count of the strokes of the positive displacement mud pump. Adder circuitry sums the lag strokes and the accumulated count of the mud pump. Comparator circuitry provides an output when the compared values of the accumulated number of strokes of the positive displacement mud pump equals the sum of the lag strokes and the strokes of the positive displacement mud pump at a predetermined depth plus the depth increment. Visual and audio indications provide notification of the arrival of borehole cuttings from preselected depths.

Abstract: An oil well drilling rig (10) recirculates drilling mud which is analyzed continuously by pumping it through a gas separation unit (72) where the gases in the mud become separated and mixed with a carrier gas and are conveyed to gas analyzing devices (196) where the concentration of the different hydrocarbon components of the gases in the mud are continuously measured and the signals representative of these measurements are processed together with mud flow rate, and the carrier gas flow rate or the sample gas flow rate signals in a signal processor (64) to provide a continuous log of gas component concentration during drilling.

Abstract: Measurement while drilling apparatus for detecting and communicating information relative to downhole parameters and/or characteristics of the earth strata via an electrically conductive drill string composed of a plurality of lengths of metallic pipe connected end-to-end in series and through which a drilling fluid is caused to flow and then return to the surface through the well cavity formed between the exterior wall of the drill string and the interior wall of the well comprising a DC voltage supply for establishing a unidirectional biasing current passing through the electrically conductive drill string, drill bit and surrounding earth strata, a colloidal suspension of ferro-magnetic particles coated with a non-conductive coating forming a part of the drilling fluid and carried by the drilling fluid through the well cavity wherein the ferromagnetic particles are caused by the magnetic field to migrate toward the outer surface of the drill string and to form an insulative coating thereon, a downhole modul