US20150285062A1 - Downhole electromagnetic telemetry apparatus - Google Patents
Downhole electromagnetic telemetry apparatus Download PDFInfo
- Publication number
- US20150285062A1 US20150285062A1 US14/441,127 US201314441127A US2015285062A1 US 20150285062 A1 US20150285062 A1 US 20150285062A1 US 201314441127 A US201314441127 A US 201314441127A US 2015285062 A1 US2015285062 A1 US 2015285062A1
- Authority
- US
- United States
- Prior art keywords
- electrically
- probe
- gap sub
- gap
- insulating layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000523 sample Substances 0.000 claims abstract description 64
- 238000005553 drilling Methods 0.000 claims abstract description 53
- 239000012777 electrically insulating material Substances 0.000 claims abstract description 8
- 230000008878 coupling Effects 0.000 claims description 41
- 238000010168 coupling process Methods 0.000 claims description 41
- 238000005859 coupling reaction Methods 0.000 claims description 41
- 239000012530 fluid Substances 0.000 claims description 27
- 238000000034 method Methods 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 11
- 239000011248 coating agent Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 239000005060 rubber Substances 0.000 claims description 5
- 239000004593 Epoxy Substances 0.000 claims description 4
- 239000000919 ceramic Substances 0.000 claims description 4
- 238000002955 isolation Methods 0.000 claims description 4
- 230000005465 channeling Effects 0.000 claims description 3
- 125000003700 epoxy group Chemical group 0.000 claims description 3
- 229920000647 polyepoxide Polymers 0.000 claims description 3
- 229920000642 polymer Polymers 0.000 claims description 3
- 229920001169 thermoplastic Polymers 0.000 claims description 3
- 239000004416 thermosoftening plastic Substances 0.000 claims description 3
- 238000013017 mechanical damping Methods 0.000 claims description 2
- 239000012815 thermoplastic material Substances 0.000 claims 1
- 230000001965 increasing effect Effects 0.000 abstract description 3
- 239000004696 Poly ether ether ketone Substances 0.000 description 4
- 238000007792 addition Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000005755 formation reaction Methods 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 229920002530 polyetherether ketone Polymers 0.000 description 4
- 229920000139 polyethylene terephthalate Polymers 0.000 description 4
- 239000005020 polyethylene terephthalate Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- -1 polyethylene terephthalate Polymers 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000004941 influx Effects 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- E21B47/122—
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/003—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings with electrically conducting or insulating means
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/01—Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
- E21B47/13—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling by electromagnetic energy, e.g. radio frequency
Definitions
- This application relates to subsurface drilling, specifically to apparatus for telemetry of information from downhole locations. Embodiments are applicable to drilling wells for recovering hydrocarbons.
- Recovering hydrocarbons from subterranean zones relies on the process of drilling wellbores.
- Drilling fluid usually in the form of a drilling “mud” is typically pumped through the drill string.
- the drilling fluid cools and lubricates the drill bit and also carries cuttings back to the surface. Drilling fluid may also be used to help control bottom hole pressure to inhibit hydrocarbon influx from the formation into the wellbore and potential blow out at surface.
- Bottom hole assembly is the name given to the equipment at the terminal end of a drill string.
- a BHA may comprise elements such as: apparatus for steering the direction of the drilling (e.g. a steerable downhole mud motor or rotary steerable system); sensors for measuring properties of the surrounding geological formations (e.g. sensors for use in well logging); sensors for measuring downhole conditions as drilling progresses; systems for telemetry of data to the surface; stabilizers; heavy weight drill collars, pulsers and the like.
- the BHA is typically advanced into the wellbore by a string of metallic tubulars (drill pipe).
- Telemetry information can be invaluable for efficient drilling operations.
- telemetry information may be used by a drill rig crew to make decisions about controlling and steering the drill bit to optimize the drilling speed and trajectory based on numerous factors, including legal boundaries, locations of existing wells, formation properties, hydrocarbon size and location, etc.
- a crew may make intentional deviations from the planned path as necessary based on information gathered from downhole sensors and transmitted to the surface by telemetry during the drilling process. The ability to obtain real time data allows for relatively more economical and more efficient drilling operations.
- Various techniques have been used to transmit information from a location in a bore hole to the surface. These include transmitting information by generating vibrations in fluid in the bore hole (e.g. acoustic telemetry or mud pulse telemetry) and transmitting information by way of electromagnetic signals that propagate at least in part through the earth (EM telemetry).
- EM telemetry electromagnetic signals that propagate at least in part through the earth
- Other telemetry systems use hardwired drill pipe or fibre optic cable to carry data to the surface.
- a typical arrangement for electromagnetic telemetry uses parts of the drill string as an antenna.
- the drill string may be divided into two conductive sections by including an insulating joint or connector (a “gap sub”) in the drill string.
- the gap sub is typically placed within a bottom hole assembly such that metallic drill pipe in the drill string above the BHA serves as one antenna element and metallic sections in the BHA serve as another antenna element.
- Electromagnetic telemetry signals can then be transmitted by applying electrical signals between the two antenna elements.
- the signals typically comprise very low frequency AC signals applied in a manner that codes information for transmission to the surface.
- the electromagnetic signals may be detected at the surface, for example by measuring electrical potential differences between the drill string and one or more ground rods.
- a challenge with EM telemetry is that the generated signals are significantly attenuated as they propagate to the surface. Further, the electrical power available to generate EM signals may be provided by batteries or another power source that has limited capacity. Therefore, it is desirable to provide a system in which EM signals are generated efficiently.
- the gap sub is an important factor in an EM telemetry system.
- the gap sub must provide electrical isolation between two parts of the drill string as well as withstand the extreme mechanical loading induced during drilling and the high differential pressures that occur between the center and exterior of the drill pipe.
- Drill string components are typically made from high strength, ductile metal alloys in order to handle the loading without failure.
- Most electrically-insulating materials suitable for electrically isolating different parts of a gap sub are weaker than metals (e.g. rubber, plastic, epoxy) or quite brittle (ceramics). This makes it difficult to design a gap sub that is both configured to provide efficient transmission of EM telemetry signals and has the mechanical properties required of a link in the drill string.
- the invention has several aspects.
- One aspect provides EM telemetry apparatus for downhole applications.
- Another aspect provides methods for subsurface drilling.
- Apparatus provides a subsurface drilling assembly comprising a downhole probe and a gap sub.
- the gap sub comprises an electrically-conducting uphole part comprising an uphole coupling for coupling into a drill string, an electrically-conducting downhole part comprising a downhole coupling for coupling into the drill string, a bore extending through the gap sub from the uphole coupling to the downhole coupling and an electrically-insulating gap portion electrically isolating the uphole part of the gap sub from the downhole part of the gap sub.
- the probe extends within the bore.
- the probe comprises an elongated housing enclosing electronics including a signal generator.
- the probe comprises first and second electrical contacts spaced apart longitudinally on an outside of the housing.
- the apparatus comprises a fluid-carrying channel bypassing the probe. Walls of the fluid-carrying channel are electrically-insulating at least in a section of the channel extending longitudinally from a location above the electrically-insulating gap portion to a location below the electrically-insulating gap portion.
- Apparatus provides a probe for use in subsurface drilling.
- the probe comprises an elongated metallic housing.
- the housing encloses electronics, including a telemetry signal generator.
- the housing comprises first and second electrical contacts spaced apart longitudinally on the outside of the housing and an electrically-insulating gap comprising an electrically-insulating material providing electrical isolation between first and second parts of the metallic housing.
- the gap is located between the first and second electrical contacts.
- the probe also comprises an electrically-insulating layer on an outside surface of the metallic housing.
- the electrically insulating layer at least partially covers the electrically-insulating gap and extends continuously to cover an outside surface of the metallic housing on at least one side of the gap. In some embodiments the covering extends for a distance of at least 1 meter.
- the probe is combined with a gap sub.
- the gap sub (which may comprise one component or a plurality of separable components comprises an electrically-conducting uphole part comprising an uphole coupling for coupling into a drill string, an electrically-conducting downhole part comprising a downhole coupling for coupling into the drill string, a bore extending through the gap sub from the uphole coupling to the downhole coupling and an electrically-insulating gap portion electrically isolating the uphole part of the gap sub from the downhole part of the gap sub.
- the probe is located within the bore of the gap sub and the first electrical contact is in electrical contact with the uphole part of the gap sub and the second electrical contact is in electrical contact with the downhole part of the gap sub.
- Apparatus provides a subsurface drilling assembly comprising a gap sub.
- the gap sub comprises an electrically-conducting uphole part comprising an uphole coupling for coupling into a drill string, an electrically-conducting downhole part comprising a downhole coupling for coupling into the drill string, a bore extending through the gap sub from the uphole coupling to the downhole coupling and an electrically-insulating gap portion electrically isolating the uphole part of the gap sub from the downhole part of the gap sub.
- An EM telemetry signal generator is housed within a wall of the gap sub. The EM telemetry signal generator has output leads electrically coupled to the uphole and downhole parts of the gap sub.
- An electrically-insulating sleeve lines at least a portion of the bore of the gap sub adjacent to the electrically-insulating gap.
- the electrically insulating sleeve covers at least one interface between the electrically insulating gap portion of the gap sub and one of the uphole and downhole parts of the gap sub and extends continuously along the one of the uphole and downhole parts of the gap sub.
- a method provides a subsurface drilling method performed using a drill string comprising a gap sub and an electronics package located in a bore of the gap sub.
- the electronics package comprises electrical contacts that are in electrical contact with electrically-conductive parts of the gap sub.
- the method comprises passing a drilling fluid down a bore of the drill string and, at the location of the electronics package, channeling the drilling fluid into a channel that is electrically insulated from both the electrically conductive parts of the gap sub and electrically conductive parts of the housing of the electronics package.
- FIG. 1 is a schematic view of a drilling operation according to an example embodiment.
- FIG. 2 is a longitudinal cross sectional view of a gap sub according to an example embodiment.
- FIGS. 3A-3D are cutaway views of a portion of a gap sub according to an example embodiment.
- FIG. 4 is a schematic view of an equivalent electrical circuit for a telemetry signal generator and gap sub according to an example embodiment.
- FIG. 5 is a cutaway view of a gap sub with radially-inwardly extending parts according to an example embodiment.
- FIG. 5A is an axial cross sectional view of a gap sub with radially-inwardly extending parts according to an example embodiment.
- FIG. 6 shows schematically an example embodiment in which an electronics package is located in a cavity in a wall of a gap sub.
- FIG. 1 shows schematically an example drilling operation.
- a drill rig 10 drives a drill string 12 which includes sections of drill pipe that extend to a drill bit 14 .
- the illustrated drill rig 10 includes a derrick 10 A, a rig floor 10 B and draw works 10 C for supporting the drill string.
- Drill bit 14 is larger in diameter than the drill string above the drill bit.
- An annular region 15 surrounding the drill string is typically filled with drilling fluid. The drilling fluid is pumped through a bore in the drill string to the drill bit and returns to the surface through annular region 15 carrying cuttings from the drilling operation.
- a casing 16 may be made in the well bore.
- a blow out preventer 17 is supported at a top end of the casing.
- the drill rig illustrated in FIG. 1 is an example only. The methods and apparatus described herein are not specific to any particular type of drill rig.
- Drill string 12 includes a gap sub 20 .
- An EM signal generator 18 located inside the drill string (for example in an electronics probe contained within the bore of the drill string) is electrically connected across the electrically-insulating gap of the gap sub 20 .
- the signals from the EM signal generator result in electrical currents 19 A and electric fields 19 B that are detectable at the surface.
- a signal receiver 13 is connected by signal cables 13 A to measure potential differences between electrical grounding stakes 13 B and the top end of drill string 12 .
- a display 11 may be connected to display data received by the signal receiver 13 .
- FIG. 2 shows an example arrangement of a gap sub 20 .
- Gap sub 20 has an electrically-conducting uphole portion 20 A and an electrically conducting downhole portion 20 B separated by gap 20 C filled with an electrically-insulating material.
- Couplings 21 for coupling to adjacent elements of the drill string are provided at the uphole and downhole ends of gap sub 20 .
- An electronics package 22 comprising an EM telemetry signal generator (not shown in FIG. 2 ) is supported in a bore 20 D of gap sub 20 .
- Electronics package 22 has a metal housing 23 comprising first and second parts 23 A and 23 B that are electrically insulated from one another by an electrically-insulating gap 23 C.
- First and second electrodes 24 A and 24 B are connected to the telemetry signal generator and are respectively in contact with the uphole portion 20 A and the downhole portion 20 B of gap sub 20 .
- Electrode 24 A may be, but is not necessarily, in electrical contact with first part 23 A of the housing of electronics package 22 .
- Electrode 24 B may be, but is not necessarily in electrical contact with second part 23 B of the housing of electronics package 22 .
- An electrically-insulating layer 25 at least partially covers electrically-insulating gap 23 C of electronics package 22 .
- Electrically insulating layer 25 extends over the outside surface of electronics package 22 and continuously covers the outside surface of conductive housing 23 of electronics package 22 for a distance beyond electrically-insulating gap 23 C on one or both sides of electrically-insulating gap 23 C.
- the length of continuous coverage of electrically-insulating layer 25 is at least 1 meter and preferably at least 11 ⁇ 2 meters or 2 meters. In some example embodiments the length of continuous coverage of electrically-insulating layer 25 is 3 to 4 meters.
- electrically-insulating layer 25 continuously covers at least 60% or 70% or 80% of that portion of the outside surface of electronics package 22 that lies between electrodes 24 A and 24 B. In some embodiments electrically insulating layer 25 continuously covers substantially all of that portion of the outside surface of electronics package 22 that lies between electrodes 24 A and 24 B. Here, ‘substantially all’ means at least 95%.
- electrically-insulating layer 25 comprises a coating applied to electronics package 22 , a sleeve or tube extending around electronics package 22 , or the like.
- the material of layer 25 may be any electrically insulating material suitable for exposure to downhole conditions. Some non-limiting examples are suitable thermoplastics, epoxies, ceramics, elastomeric polymers, and rubber.
- Layer 25 may comprise a coating that is applied to, or bonded to electronics package 22 or a pre-formed component (formed e.g. by extrusion, injection molding, or the like which is subsequently attached to, affixed around, or supported around electronics package 22 .
- the material of layer 25 should be capable of withstanding downhole conditions without degradation.
- the ideal material can withstand temperature of up to at least 150 C (preferably 175 C or 200 C or more), is chemically resistant or inert to any drilling fluid to which it will be exposed, does not absorb fluid to any significant degree and resists erosion by drilling fluid.
- An example of a suitable material is PET (polyethylene terephthalate) or PEEK (polyether ether ketone).
- a second electrically-insulating layer 26 is provided between electronics package 22 and the inner surfaces of the electrically-conducting uphole and/or downhole parts 20 A and 20 B of gap sub 20 .
- Electrically insulating layer 26 extends to at least partially cover the inner side of electrically-insulating gap 20 C and extends continuously to cover electrically-conductive parts of the bore wall on at least one side of electrically-insulating gap 20 C.
- electrically insulating layer 26 continuously covers a part of the bore wall that includes the inner side of electrically-insulating gap 20 C and extends continuously to cover parts of both uphole and downhole parts 20 A and 20 B of gap sub 20 .
- electrically insulating layer 26 comprises a coating applied to the inside of gap sub 20 , a sleeve or tube extending around the inside of gap sub 20 , or the like.
- the material of layer 26 may be any electrically insulating material suitable for exposure to downhole conditions. Some non-limiting examples are suitable thermoplastics, epoxies, ceramics, elastomeric polymers, and rubber. Layer 26 may comprise a coating that is applied to, formed on or bonded to the inner wall of gap sub 20 or a pre-formed component (formed e.g. by extrusion, injection molding, or the like) which is subsequently attached to, affixed around, supported around the inside of the bore of gap sub 20 .
- a suitable material is PET (polyethylene terephthalate) or PEEK (polyether ether ketone).
- the inventors have determined that low impedance paths within the bore of a gap sub can provide a significant source of inefficiency in the transmission of EM telemetry signals.
- the provision of electrically insulating layer 25 especially in combination with the provision of electrically insulating layer 26 has been found to dramatically reduce losses arising from conduction currents within the bore of the gap sub.
- electrically-insulating layers 25 and 26 lining electrically-conductive surfaces within bore 27 , the shortest path through the fluid in bore 27 electrically connecting parts 20 A and 20 B of gap sub 20 is at least the length of the shorter one of electrically-insulating layers 25 and 26 .
- FIGS. 3A to 3D illustrate possible electrical conduction paths through which current originating from electrodes 24 A and 24 B could pass. It can be seen that all of these possible electrical conduction paths are blocked by at least one of electrically-insulating layer 25 , electrically-insulating layer 26 , electrically-insulating gap 23 C, and electrically-insulating gap 20 C.
- insulating layers 25 and 26 should be sufficient to raise the impedance of the conductive paths through the bore fluid to a desired degree. Providing electrically insulating layers 25 and 26 that are at least approximately 2 meters (6 feet) long has been shown to reduce power lost as a result of current flowing inside the borehole by 90% or more in some cases.
- insulating layers 25 and 26 are at least 1 meter in length (although they could be shorter in some embodiments). In some embodiments insulating layer 26 extends for a length that is at least 75% of the length of electrically insulating layer 25 . In preferred embodiments, electrically insulating layer 26 is at least as long as electrically insulating layer 25 . In some embodiments, electrically insulating layer 26 covers substantially the entire inside of that portion of the bore of gap sub 20 lying between electrodes 24 A and 24 B.
- FIG. 4 illustrates schematically an equivalent electrical circuit for the telemetry signal generator and gap sub 20 (neglecting capacitive and inductive effects).
- Resistor R IN represents the available current paths within the bore 20 D of the gap sub 20 and resistor R OUT represents the available current paths external to the gap sub 20 .
- Dual non-conductive layers 25 and 26 provide an effectively large internal isolation path (a large value for R IN ) thus increasing the electrical efficiency of the gap sub 20 EM telemetry by providing an internal resistance (R IN ) between antenna elements of the gap sub 20 that is large compared to the resistance of the external gap (R OUT ).
- Another advantage of providing non-conductive layers on both the inner surface of gap sub 20 and the outer surface of electronics package 22 is that layers 25 and 26 prevent conductive outer surfaces of electronics package 22 from making electrical contact with inner surfaces of gap sub 20 as might possibly occur in cases where the electronics package and gap sub are subjected to high shocks and/or vibration. Such contact could damage a telemetry signal generator (e.g. by shorting its output) and/or interfere with telemetry of downhole information.
- a centralizer may optionally be provided to maintain electronics package 22 central in bore 20 D of gap sub 20 .
- Various centralizer designs are used. Any suitable centralizer may be used.
- one or both of layers 25 and 26 is integrated with a centralizer.
- centralizing members such as longitudinally-extending ridges or bumps or other protrusions may be provided on one or both of layers 25 and 26 to maintain electronics package 22 centered in the bore of gap sub 20 .
- the centralizing members may comprise a resilient elastomeric or vibration dampening material such as rubber or a suitable plastic, for example.
- Providing electrically-insulating layers 25 and/or 26 also allows the minimum spacing between the inner surfaces of electrically conducting parts 20 A and 20 B of gap sub 20 and the outer surface of the housing 23 of electronics package 22 to be reduced significantly without causing losses due to conduction through the fluid within the bore of gap sub 20 to increase significantly. This is particularly significant where the drilling fluids being used are of a type that provides relatively low electrical impedance. Water-based drilling fluids tend to have lower electrical impedance.
- Providing electrically-insulating layers 25 and/or 26 also allows the width of gap 20 C inside the bore of gap sub 20 and the width of gap 23 C to be reduced. Reducing the widths of gaps 20 C and/or 23 C can result in more robust apparatus since most available electrically-insulating materials suitable for gaps 23 C and 20 C are less robust than the materials (most typically metals) used for other parts of gap sub 20 and housing 23 .
- Electrically-insulating layers 25 and 26 A also alleviate any need to align gap 20 C of gap sub 20 with gap 23 C of electronics package 22 .
- gap 20 C is longitudinally spaced apart from Gap 23 C.
- the provision of electrically-insulating layers 25 and 26 allows the longitudinal position of electronics package 22 to be adjusted without causing problems that might otherwise arise from the misalignment of gaps 20 C and 23 C.
- the location of gap 23 C on electronics package 22 may be selected for optimum mechanical properties and/or for optimum placement of electronics systems and components within electronics package 22 when it is unnecessary for gap 23 C to be aligned longitudinally with gap 20 C.
- electrically conducting parts 20 A and 20 B of gap sub 20 are formed to provide parts that extend radially inwardly to provide support to electronics package 22 .
- the radially-inwardly extending parts may be integrally formed with parts 20 A and 20 B of the same metal.
- FIG. 5 illustrates an example apparatus 50 comprising a gap sub 20 that is formed to provide radially-inwardly extending parts in the form of rounded lobes 52 that extend longitudinally within bore 20 D of gap sub 20 .
- Lobes 52 may extend for substantially the full length of electronics package 22 .
- Lobes 52 may be formed, for example, by hobbing.
- FIG. 5A shows an example embodiment wherein an electrically insulating layer 25 is provided on the outside of electronics package 22 .
- Another electrically insulating layer 26 A is preferably but optionally provided on the inside of the bore of gap sub 20 covering lobes 52 .
- lobes 52 are dimensioned such that electronics package 22 is firmly held within their inwardly-facing tips.
- Electrically-insulating layers 25 and/or 26 A may be of materials that provide mechanical damping as well as electrical insulation. Mechanically coupling electronics package 22 to gap sub 20 continuously along its length can substantially reduce flexing and vibration of electronics package 22 caused by lateral accelerations of the drill string, flow of drilling fluid, or the like.
- Apparatus as described herein may be applied in a wide range of subsurface drilling applications.
- the apparatus may be applied to provide telemetry in logging while drilling (‘LWD’) and/or measuring while drilling (‘MWD’) applications.
- LWD logging while drilling
- MWD measuring while drilling
- Providing apparatus as described herein in which electrical current flow between different antenna elements within the bore of a drill string is significantly diminished reduces the load on a telemetry signal generator. This in turn may permit the same telemetry signal generator to operate with a reduced power output and/or to provide a higher-voltage signal to the antenna elements, thereby facilitating one or more of extended battery life, reduced power consumption, improved telemetry signal strength at the surface and reduced telemetry error rate.
- Extended battery life in downhole applications is very significant since battery replacement or recharging may require withdrawal of the electronics package from the hole. This can be time consuming and labor intensive. Thus, increased battery life can result in a longer run length during drilling operations with fewer service intervals needed.
- Another aspect of the invention provides a subsurface drilling method.
- the method is performed using a drill string comprising a gap sub and an electronics package located in a bore of the gap sub.
- the electronics package has electrical contacts that are in electrical contact with electrically-conductive parts of the gap sub.
- the method involves passing a drilling fluid down a bore of the drill string and, at the location of the electronics package, channeling the drilling fluid into a channel that is electrically insulated from both the electrically conductive parts of the gap sub and electrically conductive parts of the housing of the electronics package.
- the channel is an annular channel that surrounds that portion of the electronics package between the electrodes. This is not mandatory, however.
- gap sub be a single component.
- a gap sub comprises a plurality of components that can be assembled together into the drill string to provide electrical insulation between two parts of the drill string.
- a probe may extend fully or partially through one, two, three, or more coupled-together sections of the drill string.
- electronic systems which may include a telemetry signal generator are provided in a package located in a cavity formed in a wall of a drill collar or gap sub. Such embodiments may not have a separate probe mounted in a bore of the drill collar or gap sub. Electrical connections between an EM telemetry signal generator housed in a wall of a drill string section and uphole and downhole portions 20 A and 20 B of the gap sub may be made by way of conductors embedded in the wall of the gap sub.
- FIG. 6 shows schematically an example embodiment in which an electronics package 60 is located in a cavity 61 in a wall of a gap sub 20 .
- efficiency of EM telemetry may be improved by providing an electrically-insulating layer 26 that at least partially covers the inside of electrically-insulating gap 20 C and extends to continuously cover parts of one or both of the inner surfaces of the electrically-conducting uphole and downhole parts 20 A and 20 B of gap sub 20 that are adjacent to electrically-insulating gap 20 C.
- the electrically-insulating layer 26 covers at least one of the interfaces 62 between electrically-insulating gap 20 C and uphole and downhole parts 20 A and 20 B.
- a component e.g. a circuit, module, assembly, device, drill string component, drill rig system etc.
- reference to that component should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Geochemistry & Mineralogy (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Geophysics (AREA)
- Remote Sensing (AREA)
- Electromagnetism (AREA)
- Mechanical Engineering (AREA)
- Earth Drilling (AREA)
- Geophysics And Detection Of Objects (AREA)
- Near-Field Transmission Systems (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
Abstract
Description
- This application claims priority from U.S. Application No. 61/723,286, filed 6 Nov. 2012. For purposes of the United States, this application claims the benefit under 35 U.S.C. §119 of U.S. Application No. 61/723,286, filed 6 Nov. 2012 and entitled DOWNHOLE ELECTROMAGNETIC TELEMETRY APPARATUS which is hereby incorporated herein by reference for all purposes.
- This application relates to subsurface drilling, specifically to apparatus for telemetry of information from downhole locations. Embodiments are applicable to drilling wells for recovering hydrocarbons.
- Recovering hydrocarbons from subterranean zones relies on the process of drilling wellbores.
- Wellbores are made using surface-located drilling equipment which drives a drill string that eventually extends from the surface equipment to the formation or subterranean zone of interest. The drill string can extend thousands of feet or meters below the surface. The terminal end of the drill string includes a drill bit for drilling (or extending) the wellbore. Drilling fluid usually in the form of a drilling “mud” is typically pumped through the drill string. The drilling fluid cools and lubricates the drill bit and also carries cuttings back to the surface. Drilling fluid may also be used to help control bottom hole pressure to inhibit hydrocarbon influx from the formation into the wellbore and potential blow out at surface.
- Bottom hole assembly (BHA) is the name given to the equipment at the terminal end of a drill string. In addition to a drill bit a BHA may comprise elements such as: apparatus for steering the direction of the drilling (e.g. a steerable downhole mud motor or rotary steerable system); sensors for measuring properties of the surrounding geological formations (e.g. sensors for use in well logging); sensors for measuring downhole conditions as drilling progresses; systems for telemetry of data to the surface; stabilizers; heavy weight drill collars, pulsers and the like. The BHA is typically advanced into the wellbore by a string of metallic tubulars (drill pipe).
- Telemetry information can be invaluable for efficient drilling operations. For example, telemetry information may be used by a drill rig crew to make decisions about controlling and steering the drill bit to optimize the drilling speed and trajectory based on numerous factors, including legal boundaries, locations of existing wells, formation properties, hydrocarbon size and location, etc. A crew may make intentional deviations from the planned path as necessary based on information gathered from downhole sensors and transmitted to the surface by telemetry during the drilling process. The ability to obtain real time data allows for relatively more economical and more efficient drilling operations.
- Various techniques have been used to transmit information from a location in a bore hole to the surface. These include transmitting information by generating vibrations in fluid in the bore hole (e.g. acoustic telemetry or mud pulse telemetry) and transmitting information by way of electromagnetic signals that propagate at least in part through the earth (EM telemetry). Other telemetry systems use hardwired drill pipe or fibre optic cable to carry data to the surface.
- A typical arrangement for electromagnetic telemetry uses parts of the drill string as an antenna. The drill string may be divided into two conductive sections by including an insulating joint or connector (a “gap sub”) in the drill string. The gap sub is typically placed within a bottom hole assembly such that metallic drill pipe in the drill string above the BHA serves as one antenna element and metallic sections in the BHA serve as another antenna element. Electromagnetic telemetry signals can then be transmitted by applying electrical signals between the two antenna elements. The signals typically comprise very low frequency AC signals applied in a manner that codes information for transmission to the surface. The electromagnetic signals may be detected at the surface, for example by measuring electrical potential differences between the drill string and one or more ground rods. A challenge with EM telemetry is that the generated signals are significantly attenuated as they propagate to the surface. Further, the electrical power available to generate EM signals may be provided by batteries or another power source that has limited capacity. Therefore, it is desirable to provide a system in which EM signals are generated efficiently.
- Design of the gap sub is an important factor in an EM telemetry system. The gap sub must provide electrical isolation between two parts of the drill string as well as withstand the extreme mechanical loading induced during drilling and the high differential pressures that occur between the center and exterior of the drill pipe. Drill string components are typically made from high strength, ductile metal alloys in order to handle the loading without failure. Most electrically-insulating materials suitable for electrically isolating different parts of a gap sub are weaker than metals (e.g. rubber, plastic, epoxy) or quite brittle (ceramics). This makes it difficult to design a gap sub that is both configured to provide efficient transmission of EM telemetry signals and has the mechanical properties required of a link in the drill string.
- The following references describe various telemetry systems: U.S. Pat. No. 3323327; U.S. Pat. No. 4,176,894; U.S. Pat. No. 4,348,672; U.S. Pat. No. 4,496,174; U.S. Pat. No. 4,684,946; U.S. Pat. No. 4,676,773; U.S. Pat. No. 4,739,325; U.S. Pat. No. 5,130,706; U.S. Pat. No. 5,138,313; U.S. Pat. No. 5,236,048; U.S. Pat. No. 5,406,983; U.S. Pat. No. 5,467,832; U.S. Pat. No. 5,520,246; U.S. Pat. No. 5,749,605; U.S. Pat. No. 5,883,516; U.S. Pat. No. 6,050,353; U.S. Pat. No. 6,098,727; U.S. Pat. No. 6,158,532; U.S. Pat. No. 6,404,350; U.S. Pat. No. 6,446,736; U.S. Pat. No. 6,515,592; U.S. Pat. No. 6,727,827; U.S. Pat. No. 6,750,783; U.S. Pat. No. 6,926,098; U.S. Pat. No. 7,151,466; U.S. Pat. No. 7,243,028; U.S. Pat. No. 7,255,183; U.S. Pat. No. 7,252,160; U.S. Pat. No. 7,326,015; U.S. Pat. No. 7,387,167; U.S. Pat. No. 7,573,397; U.S. Pat. No. 7,605,716; U.S. Pat. No. 7,836,973; U.S. Pat. No. 7,880,640; U.S. Pat. No. 7,900,968; U.S. Pat. No. 8,154,420 US 2004/0104047; US 2005/0217898; US 2006/0202852; US 2006/003206; US 2007/0235224; US 2007/0247328; US 2009/0023502; US 2009/0065254; US 2009/0066334; US 2010/0033344; US 2011/025469; US 2011/0309949; US 2012/0085583; WO2006/083764; WO2008/116077; WO2009/086637; WO2011/049573; WO2010/121345; WO2010/121346; WO2011/133399; WO2012/042499; WO2011/049573; WO2012/045698; WO2012/082748.
- Despite work that has been done to develop systems for subsurface telemetry there remains a need for practical subsurface telemetry systems and there remains a need to provide such systems that offer improved efficiency and/or greater range.
- The invention has several aspects. One aspect provides EM telemetry apparatus for downhole applications. Another aspect provides methods for subsurface drilling.
- Apparatus according to one aspect provides a subsurface drilling assembly comprising a downhole probe and a gap sub. The gap sub comprises an electrically-conducting uphole part comprising an uphole coupling for coupling into a drill string, an electrically-conducting downhole part comprising a downhole coupling for coupling into the drill string, a bore extending through the gap sub from the uphole coupling to the downhole coupling and an electrically-insulating gap portion electrically isolating the uphole part of the gap sub from the downhole part of the gap sub. The probe extends within the bore. The probe comprises an elongated housing enclosing electronics including a signal generator. The probe comprises first and second electrical contacts spaced apart longitudinally on an outside of the housing. The apparatus comprises a fluid-carrying channel bypassing the probe. Walls of the fluid-carrying channel are electrically-insulating at least in a section of the channel extending longitudinally from a location above the electrically-insulating gap portion to a location below the electrically-insulating gap portion.
- Apparatus according to another aspect provides a probe for use in subsurface drilling. The probe comprises an elongated metallic housing. The housing encloses electronics, including a telemetry signal generator. The housing comprises first and second electrical contacts spaced apart longitudinally on the outside of the housing and an electrically-insulating gap comprising an electrically-insulating material providing electrical isolation between first and second parts of the metallic housing. The gap is located between the first and second electrical contacts. The probe also comprises an electrically-insulating layer on an outside surface of the metallic housing. The electrically insulating layer at least partially covers the electrically-insulating gap and extends continuously to cover an outside surface of the metallic housing on at least one side of the gap. In some embodiments the covering extends for a distance of at least 1 meter. In some embodiments the probe is combined with a gap sub. The gap sub (which may comprise one component or a plurality of separable components comprises an electrically-conducting uphole part comprising an uphole coupling for coupling into a drill string, an electrically-conducting downhole part comprising a downhole coupling for coupling into the drill string, a bore extending through the gap sub from the uphole coupling to the downhole coupling and an electrically-insulating gap portion electrically isolating the uphole part of the gap sub from the downhole part of the gap sub. In the combination, the probe is located within the bore of the gap sub and the first electrical contact is in electrical contact with the uphole part of the gap sub and the second electrical contact is in electrical contact with the downhole part of the gap sub.
- Apparatus according to another aspect provides a subsurface drilling assembly comprising a gap sub. The gap sub comprises an electrically-conducting uphole part comprising an uphole coupling for coupling into a drill string, an electrically-conducting downhole part comprising a downhole coupling for coupling into the drill string, a bore extending through the gap sub from the uphole coupling to the downhole coupling and an electrically-insulating gap portion electrically isolating the uphole part of the gap sub from the downhole part of the gap sub. An EM telemetry signal generator is housed within a wall of the gap sub. The EM telemetry signal generator has output leads electrically coupled to the uphole and downhole parts of the gap sub. An electrically-insulating sleeve lines at least a portion of the bore of the gap sub adjacent to the electrically-insulating gap. The electrically insulating sleeve covers at least one interface between the electrically insulating gap portion of the gap sub and one of the uphole and downhole parts of the gap sub and extends continuously along the one of the uphole and downhole parts of the gap sub.
- A method according to a further aspect provides a subsurface drilling method performed using a drill string comprising a gap sub and an electronics package located in a bore of the gap sub. The electronics package comprises electrical contacts that are in electrical contact with electrically-conductive parts of the gap sub. The method comprises passing a drilling fluid down a bore of the drill string and, at the location of the electronics package, channeling the drilling fluid into a channel that is electrically insulated from both the electrically conductive parts of the gap sub and electrically conductive parts of the housing of the electronics package.
- Further aspects of the invention and features of example embodiments are illustrated in the accompanying drawings and/or described in the following description.
- The accompanying drawings illustrate non-limiting example embodiments of the invention.
-
FIG. 1 is a schematic view of a drilling operation according to an example embodiment. -
FIG. 2 is a longitudinal cross sectional view of a gap sub according to an example embodiment. -
FIGS. 3A-3D are cutaway views of a portion of a gap sub according to an example embodiment. -
FIG. 4 is a schematic view of an equivalent electrical circuit for a telemetry signal generator and gap sub according to an example embodiment. -
FIG. 5 is a cutaway view of a gap sub with radially-inwardly extending parts according to an example embodiment. -
FIG. 5A is an axial cross sectional view of a gap sub with radially-inwardly extending parts according to an example embodiment. -
FIG. 6 shows schematically an example embodiment in which an electronics package is located in a cavity in a wall of a gap sub. - Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. The following description of examples of the technology is not intended to be exhaustive or to limit the system to the precise forms of any example embodiment. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.
- While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.
-
FIG. 1 shows schematically an example drilling operation. Adrill rig 10 drives adrill string 12 which includes sections of drill pipe that extend to adrill bit 14. The illustrateddrill rig 10 includes aderrick 10A, arig floor 10B and draw works 10C for supporting the drill string.Drill bit 14 is larger in diameter than the drill string above the drill bit. Anannular region 15 surrounding the drill string is typically filled with drilling fluid. The drilling fluid is pumped through a bore in the drill string to the drill bit and returns to the surface throughannular region 15 carrying cuttings from the drilling operation. As the well is drilled, acasing 16 may be made in the well bore. A blow outpreventer 17 is supported at a top end of the casing. The drill rig illustrated inFIG. 1 is an example only. The methods and apparatus described herein are not specific to any particular type of drill rig. -
Drill string 12 includes agap sub 20. AnEM signal generator 18 located inside the drill string (for example in an electronics probe contained within the bore of the drill string) is electrically connected across the electrically-insulating gap of thegap sub 20. The signals from the EM signal generator result inelectrical currents 19A andelectric fields 19B that are detectable at the surface. In the illustrated embodiment asignal receiver 13 is connected bysignal cables 13A to measure potential differences between electrical grounding stakes 13B and the top end ofdrill string 12. Adisplay 11 may be connected to display data received by thesignal receiver 13. -
FIG. 2 shows an example arrangement of agap sub 20.Gap sub 20 has an electrically-conductinguphole portion 20A and an electrically conductingdownhole portion 20B separated bygap 20C filled with an electrically-insulating material.Couplings 21 for coupling to adjacent elements of the drill string are provided at the uphole and downhole ends ofgap sub 20. Anelectronics package 22 comprising an EM telemetry signal generator (not shown inFIG. 2 ) is supported in abore 20D ofgap sub 20. -
Electronics package 22 has ametal housing 23 comprising first andsecond parts gap 23C. First andsecond electrodes uphole portion 20A and thedownhole portion 20B ofgap sub 20.Electrode 24A may be, but is not necessarily, in electrical contact withfirst part 23A of the housing ofelectronics package 22.Electrode 24B may be, but is not necessarily in electrical contact withsecond part 23B of the housing ofelectronics package 22. - An electrically-insulating
layer 25 at least partially covers electrically-insulatinggap 23C ofelectronics package 22. Electrically insulatinglayer 25 extends over the outside surface ofelectronics package 22 and continuously covers the outside surface ofconductive housing 23 ofelectronics package 22 for a distance beyond electrically-insulatinggap 23C on one or both sides of electrically-insulatinggap 23C. In some embodiments the length of continuous coverage of electrically-insulatinglayer 25 is at least 1 meter and preferably at least 1½ meters or 2 meters. In some example embodiments the length of continuous coverage of electrically-insulatinglayer 25 is 3 to 4 meters. - In some embodiments, electrically-insulating
layer 25 continuously covers at least 60% or 70% or 80% of that portion of the outside surface ofelectronics package 22 that lies betweenelectrodes layer 25 continuously covers substantially all of that portion of the outside surface ofelectronics package 22 that lies betweenelectrodes - In some embodiments, electrically-insulating
layer 25 comprises a coating applied toelectronics package 22, a sleeve or tube extending aroundelectronics package 22, or the like. The material oflayer 25 may be any electrically insulating material suitable for exposure to downhole conditions. Some non-limiting examples are suitable thermoplastics, epoxies, ceramics, elastomeric polymers, and rubber.Layer 25 may comprise a coating that is applied to, or bonded toelectronics package 22 or a pre-formed component (formed e.g. by extrusion, injection molding, or the like which is subsequently attached to, affixed around, or supported aroundelectronics package 22. The material oflayer 25 should be capable of withstanding downhole conditions without degradation. The ideal material can withstand temperature of up to at least 150 C (preferably 175 C or 200 C or more), is chemically resistant or inert to any drilling fluid to which it will be exposed, does not absorb fluid to any significant degree and resists erosion by drilling fluid. An example of a suitable material is PET (polyethylene terephthalate) or PEEK (polyether ether ketone). - A second electrically-insulating
layer 26 is provided betweenelectronics package 22 and the inner surfaces of the electrically-conducting uphole and/ordownhole parts gap sub 20. Electrically insulatinglayer 26 extends to at least partially cover the inner side of electrically-insulatinggap 20C and extends continuously to cover electrically-conductive parts of the bore wall on at least one side of electrically-insulatinggap 20C. In some embodiments electrically insulatinglayer 26 continuously covers a part of the bore wall that includes the inner side of electrically-insulatinggap 20C and extends continuously to cover parts of both uphole anddownhole parts gap sub 20. In some embodiments electrically insulatinglayer 26 comprises a coating applied to the inside ofgap sub 20, a sleeve or tube extending around the inside ofgap sub 20, or the like. - As with
layer 25, the material oflayer 26 may be any electrically insulating material suitable for exposure to downhole conditions. Some non-limiting examples are suitable thermoplastics, epoxies, ceramics, elastomeric polymers, and rubber.Layer 26 may comprise a coating that is applied to, formed on or bonded to the inner wall ofgap sub 20 or a pre-formed component (formed e.g. by extrusion, injection molding, or the like) which is subsequently attached to, affixed around, supported around the inside of the bore ofgap sub 20. An example of a suitable material is PET (polyethylene terephthalate) or PEEK (polyether ether ketone). - The inventors have determined that low impedance paths within the bore of a gap sub can provide a significant source of inefficiency in the transmission of EM telemetry signals. The provision of electrically insulating
layer 25, especially in combination with the provision of electrically insulatinglayer 26 has been found to dramatically reduce losses arising from conduction currents within the bore of the gap sub. With electrically-insulatinglayers bore 27, the shortest path through the fluid inbore 27 electrically connectingparts gap sub 20 is at least the length of the shorter one of electrically-insulatinglayers -
FIGS. 3A to 3D illustrate possible electrical conduction paths through which current originating fromelectrodes layer 25, electrically-insulatinglayer 26, electrically-insulatinggap 23C, and electrically-insulatinggap 20C. - By providing electrically insulating barriers on conductive surfaces of
electronics package 22 and/orgap sub 20 that would otherwise be exposed to the drilling fluid in the bore ofgap sub 20, considerable improvements in the efficiency of EM transmission may be achieved. The lengths of insulatinglayers layers - In example embodiments, insulating
layers embodiments insulating layer 26 extends for a length that is at least 75% of the length of electrically insulatinglayer 25. In preferred embodiments, electrically insulatinglayer 26 is at least as long as electrically insulatinglayer 25. In some embodiments, electrically insulatinglayer 26 covers substantially the entire inside of that portion of the bore ofgap sub 20 lying betweenelectrodes -
FIG. 4 illustrates schematically an equivalent electrical circuit for the telemetry signal generator and gap sub 20 (neglecting capacitive and inductive effects). Resistor RIN represents the available current paths within thebore 20D of thegap sub 20 and resistor ROUT represents the available current paths external to thegap sub 20. Dualnon-conductive layers gap sub 20 EM telemetry by providing an internal resistance (RIN) between antenna elements of thegap sub 20 that is large compared to the resistance of the external gap (ROUT). - Another advantage of providing non-conductive layers on both the inner surface of
gap sub 20 and the outer surface ofelectronics package 22 is that layers 25 and 26 prevent conductive outer surfaces ofelectronics package 22 from making electrical contact with inner surfaces ofgap sub 20 as might possibly occur in cases where the electronics package and gap sub are subjected to high shocks and/or vibration. Such contact could damage a telemetry signal generator (e.g. by shorting its output) and/or interfere with telemetry of downhole information. - A centralizer may optionally be provided to maintain
electronics package 22 central inbore 20D ofgap sub 20. Various centralizer designs are used. Any suitable centralizer may be used. In some embodiments one or both oflayers layers electronics package 22 centered in the bore ofgap sub 20. The centralizing members may comprise a resilient elastomeric or vibration dampening material such as rubber or a suitable plastic, for example. - Providing electrically-insulating
layers 25 and/or 26 also allows the minimum spacing between the inner surfaces of electrically conductingparts gap sub 20 and the outer surface of thehousing 23 ofelectronics package 22 to be reduced significantly without causing losses due to conduction through the fluid within the bore ofgap sub 20 to increase significantly. This is particularly significant where the drilling fluids being used are of a type that provides relatively low electrical impedance. Water-based drilling fluids tend to have lower electrical impedance. - Providing electrically-insulating
layers 25 and/or 26 also allows the width ofgap 20C inside the bore ofgap sub 20 and the width ofgap 23C to be reduced. Reducing the widths ofgaps 20C and/or 23C can result in more robust apparatus since most available electrically-insulating materials suitable forgaps gap sub 20 andhousing 23. - Electrically-insulating
layers gap 20C ofgap sub 20 withgap 23C ofelectronics package 22. In someembodiments gap 20C is longitudinally spaced apart fromGap 23C. Thus the provision of electrically-insulatinglayers electronics package 22 to be adjusted without causing problems that might otherwise arise from the misalignment ofgaps gap 23C onelectronics package 22 may be selected for optimum mechanical properties and/or for optimum placement of electronics systems and components withinelectronics package 22 when it is unnecessary forgap 23C to be aligned longitudinally withgap 20C. - In some embodiments, electrically conducting
parts gap sub 20 are formed to provide parts that extend radially inwardly to provide support toelectronics package 22. The radially-inwardly extending parts may be integrally formed withparts -
FIG. 5 illustrates anexample apparatus 50 comprising agap sub 20 that is formed to provide radially-inwardly extending parts in the form ofrounded lobes 52 that extend longitudinally withinbore 20D ofgap sub 20.Lobes 52 may extend for substantially the full length ofelectronics package 22.Lobes 52 may be formed, for example, by hobbing. -
FIG. 5A shows an example embodiment wherein an electrically insulatinglayer 25 is provided on the outside ofelectronics package 22. Another electrically insulatinglayer 26A is preferably but optionally provided on the inside of the bore ofgap sub 20 coveringlobes 52. - As shown in
FIG. 5A ,lobes 52 are dimensioned such thatelectronics package 22 is firmly held within their inwardly-facing tips. Electrically-insulatinglayers 25 and/or 26A may be of materials that provide mechanical damping as well as electrical insulation. Mechanicallycoupling electronics package 22 togap sub 20 continuously along its length can substantially reduce flexing and vibration ofelectronics package 22 caused by lateral accelerations of the drill string, flow of drilling fluid, or the like. - Apparatus as described herein may be applied in a wide range of subsurface drilling applications. For example, the apparatus may be applied to provide telemetry in logging while drilling (‘LWD’) and/or measuring while drilling (‘MWD’) applications. Providing apparatus as described herein in which electrical current flow between different antenna elements within the bore of a drill string is significantly diminished reduces the load on a telemetry signal generator. This in turn may permit the same telemetry signal generator to operate with a reduced power output and/or to provide a higher-voltage signal to the antenna elements, thereby facilitating one or more of extended battery life, reduced power consumption, improved telemetry signal strength at the surface and reduced telemetry error rate. Extended battery life in downhole applications is very significant since battery replacement or recharging may require withdrawal of the electronics package from the hole. This can be time consuming and labor intensive. Thus, increased battery life can result in a longer run length during drilling operations with fewer service intervals needed.
- Another aspect of the invention provides a subsurface drilling method. The method is performed using a drill string comprising a gap sub and an electronics package located in a bore of the gap sub. The electronics package has electrical contacts that are in electrical contact with electrically-conductive parts of the gap sub. The method involves passing a drilling fluid down a bore of the drill string and, at the location of the electronics package, channeling the drilling fluid into a channel that is electrically insulated from both the electrically conductive parts of the gap sub and electrically conductive parts of the housing of the electronics package. In some embodiments, examples of which are described above, the channel is an annular channel that surrounds that portion of the electronics package between the electrodes. This is not mandatory, however.
- A wide range of alternatives are possible. For example, it is not mandatory that the gap sub be a single component. In some embodiments a gap sub comprises a plurality of components that can be assembled together into the drill string to provide electrical insulation between two parts of the drill string. A probe may extend fully or partially through one, two, three, or more coupled-together sections of the drill string.
- In some embodiments, electronic systems which may include a telemetry signal generator are provided in a package located in a cavity formed in a wall of a drill collar or gap sub. Such embodiments may not have a separate probe mounted in a bore of the drill collar or gap sub. Electrical connections between an EM telemetry signal generator housed in a wall of a drill string section and uphole and
downhole portions FIG. 6 shows schematically an example embodiment in which anelectronics package 60 is located in acavity 61 in a wall of agap sub 20. In such embodiments efficiency of EM telemetry may be improved by providing an electrically-insulatinglayer 26 that at least partially covers the inside of electrically-insulatinggap 20C and extends to continuously cover parts of one or both of the inner surfaces of the electrically-conducting uphole anddownhole parts gap sub 20 that are adjacent to electrically-insulatinggap 20C. The electrically-insulatinglayer 26 covers at least one of theinterfaces 62 between electrically-insulatinggap 20C and uphole anddownhole parts layer 26 lining bore 27, the shortest path through the fluid inbore 27 electrically connectingparts gap sub 20 is at least the length of electrically-insulatinglayer 26. - Unless the context clearly requires otherwise, throughout the description and the claims:
-
- “comprise”, “comprising”, and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.
- “connected”, “coupled”, or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof.
- “herein”, “above”, “below”, and words of similar import, when used to describe this specification shall refer to this specification as a whole and not to any particular portions of this specification.
- “or”, in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
- the singular forms “a”, “an” and “the” also include the meaning of any appropriate plural forms.
- Words that indicate directions such as “vertical”, “transverse”, “horizontal”, “upward”, “downward”, “forward”, “backward”, “inward”, “outward”, “vertical”, “transverse”, “left”, “right”, “front”, “back”, “top”, “bottom”, “below”, “above”, “under”, and the like, used in this description and any accompanying claims (where present) depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly.
- Where a component (e.g. a circuit, module, assembly, device, drill string component, drill rig system etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.
- Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by: replacing features, elements and/or acts with equivalent features, elements and/or acts; mixing and matching of features, elements and/or acts from different embodiments; combining features, elements and/or acts from embodiments as described herein with features, elements and/or acts of other technology; and/or omitting combining features, elements and/or acts from described embodiments.
- It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.
Claims (48)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/441,127 US20150285062A1 (en) | 2012-11-06 | 2013-11-06 | Downhole electromagnetic telemetry apparatus |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201261723286P | 2012-11-06 | 2012-11-06 | |
PCT/CA2013/050850 WO2014071520A1 (en) | 2012-11-06 | 2013-11-06 | Downhole electromagnetic telemetry apparatus |
US14/441,127 US20150285062A1 (en) | 2012-11-06 | 2013-11-06 | Downhole electromagnetic telemetry apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
US20150285062A1 true US20150285062A1 (en) | 2015-10-08 |
Family
ID=50683876
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/441,127 Abandoned US20150285062A1 (en) | 2012-11-06 | 2013-11-06 | Downhole electromagnetic telemetry apparatus |
Country Status (7)
Country | Link |
---|---|
US (1) | US20150285062A1 (en) |
EP (1) | EP2917481B1 (en) |
CN (1) | CN104919137B (en) |
CA (1) | CA2890603C (en) |
EA (2) | EA201791477A1 (en) |
NO (1) | NO2970497T3 (en) |
WO (1) | WO2014071520A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107438697A (en) * | 2015-04-16 | 2017-12-05 | 哈利伯顿能源服务公司 | For providing the stabilizer with fin installing type electrode of signal to drill string antenna |
US20190033482A1 (en) * | 2016-12-21 | 2019-01-31 | Halliburton Energy Services, Inc. | Use of gap subs behind a coil antenna in electromagnetic induction tools |
US10428640B1 (en) * | 2018-10-15 | 2019-10-01 | Ozzie's Enterprises LLC | Borehole mapping tool and methods of mapping boreholes |
US10519762B2 (en) | 2017-06-20 | 2019-12-31 | Baker Hughes, A Ge Company, Llc | Lateral support for downhole electronics |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150315906A1 (en) * | 2012-12-28 | 2015-11-05 | Halliburton Energy Services Inc. | Downhole Electromagnetic Telemetry System Utilizing Electrically Insulating Material and Related Methods |
US9863239B2 (en) | 2014-06-19 | 2018-01-09 | Evolution Engineering Inc. | Selecting transmission frequency based on formation properties |
GB2546217B (en) | 2014-12-18 | 2020-10-14 | Halliburton Energy Services Inc | High-efficiency downhole wireless communication |
US10422217B2 (en) | 2014-12-29 | 2019-09-24 | Halliburton Energy Services, Inc. | Electromagnetically coupled band-gap transceivers |
US10641081B2 (en) | 2015-02-24 | 2020-05-05 | Evolution Engineering Inc. | Device and method for retaining probe exterior wear sleeve |
CA2931556C (en) | 2015-05-27 | 2023-09-26 | Evolution Engineering Inc. | Electromagnetic telemetry system with compensation for drilling fluid characteristics |
CN107546487B (en) * | 2016-06-29 | 2020-12-11 | 中国石油化工股份有限公司 | High-strength insulated antenna coupling assembly |
CN106593317B (en) * | 2017-02-23 | 2019-02-01 | 中国地质大学(武汉) | A kind of insulating inner tube and preparation method thereof |
GB2599064B (en) * | 2020-04-16 | 2023-05-31 | Schlumberger Technology Bv | Systems and methods for downhole communication |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2650067A (en) * | 1948-12-13 | 1953-08-25 | Philip W Martin | Apparatus for logging wells while drilling |
US20050167098A1 (en) * | 2004-01-29 | 2005-08-04 | Schlumberger Technology Corporation | [wellbore communication system] |
US20070235224A1 (en) * | 2006-04-05 | 2007-10-11 | Diamond Back - Quantum Drilling Motors, L.L.C. | Drill pipe with vibration dampening liner |
US20080041575A1 (en) * | 2006-07-10 | 2008-02-21 | Schlumberger Technology Corporation | Electromagnetic wellbore telemetry system for tubular strings |
US8020634B2 (en) * | 2005-10-05 | 2011-09-20 | Schlumberger Technology Corporation | Method and apparatus for supporting a downhole component in a downhole drilling tool |
US20150267481A1 (en) * | 2012-11-06 | 2015-09-24 | Evolution Engineering Inc. | Drill collar with integrated probe centralizer |
US9523246B2 (en) * | 2012-11-06 | 2016-12-20 | Evolution Engineering Inc. | Centralizer for downhole probes |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN100513742C (en) * | 2004-02-16 | 2009-07-15 | 中国石油集团钻井工程技术研究院 | Electromagnetic telemetering method and system of measuring by bit |
US7477162B2 (en) * | 2005-10-11 | 2009-01-13 | Schlumberger Technology Corporation | Wireless electromagnetic telemetry system and method for bottomhole assembly |
US7782060B2 (en) * | 2006-12-28 | 2010-08-24 | Schlumberger Technology Corporation | Integrated electrode resistivity and EM telemetry tool |
RU2011128000A (en) * | 2008-12-10 | 2013-01-20 | Шлюмбергер Текнолоджи Б.В. | METHOD AND DEVICE FOR LATERALLY DIRECTED WELL |
US8162044B2 (en) * | 2009-01-02 | 2012-04-24 | Joachim Sihler | Systems and methods for providing electrical transmission in downhole tools |
-
2013
- 2013-11-06 EA EA201791477A patent/EA201791477A1/en unknown
- 2013-11-06 WO PCT/CA2013/050850 patent/WO2014071520A1/en active Application Filing
- 2013-11-06 CA CA2890603A patent/CA2890603C/en active Active
- 2013-11-06 CN CN201380058061.7A patent/CN104919137B/en active Active
- 2013-11-06 EA EA201590897A patent/EA028582B1/en not_active IP Right Cessation
- 2013-11-06 EP EP13854109.9A patent/EP2917481B1/en active Active
- 2013-11-06 US US14/441,127 patent/US20150285062A1/en not_active Abandoned
-
2014
- 2014-03-14 NO NO14729504A patent/NO2970497T3/no unknown
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2650067A (en) * | 1948-12-13 | 1953-08-25 | Philip W Martin | Apparatus for logging wells while drilling |
US20050167098A1 (en) * | 2004-01-29 | 2005-08-04 | Schlumberger Technology Corporation | [wellbore communication system] |
US8020634B2 (en) * | 2005-10-05 | 2011-09-20 | Schlumberger Technology Corporation | Method and apparatus for supporting a downhole component in a downhole drilling tool |
US20070235224A1 (en) * | 2006-04-05 | 2007-10-11 | Diamond Back - Quantum Drilling Motors, L.L.C. | Drill pipe with vibration dampening liner |
US20080041575A1 (en) * | 2006-07-10 | 2008-02-21 | Schlumberger Technology Corporation | Electromagnetic wellbore telemetry system for tubular strings |
US20150267481A1 (en) * | 2012-11-06 | 2015-09-24 | Evolution Engineering Inc. | Drill collar with integrated probe centralizer |
US9523246B2 (en) * | 2012-11-06 | 2016-12-20 | Evolution Engineering Inc. | Centralizer for downhole probes |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107438697A (en) * | 2015-04-16 | 2017-12-05 | 哈利伯顿能源服务公司 | For providing the stabilizer with fin installing type electrode of signal to drill string antenna |
US20180106145A1 (en) * | 2015-04-16 | 2018-04-19 | Halliburton Energy Services, Inc. | Stabilizer with fin-mounted electrode for providing signals to drill string antenna |
US11015440B2 (en) * | 2015-04-16 | 2021-05-25 | Halliburton Energy Services, Inc. | Stabilizer with fin-mounted electrode for providing signals to drill string antenna |
US20190033482A1 (en) * | 2016-12-21 | 2019-01-31 | Halliburton Energy Services, Inc. | Use of gap subs behind a coil antenna in electromagnetic induction tools |
US11035975B2 (en) * | 2016-12-21 | 2021-06-15 | Halliburton Energy Services, Inc. | Use of gap subs behind a coil antenna in electromagnetic induction tools |
US10519762B2 (en) | 2017-06-20 | 2019-12-31 | Baker Hughes, A Ge Company, Llc | Lateral support for downhole electronics |
US10428640B1 (en) * | 2018-10-15 | 2019-10-01 | Ozzie's Enterprises LLC | Borehole mapping tool and methods of mapping boreholes |
US10947835B2 (en) * | 2018-10-15 | 2021-03-16 | Ozzie's Enterprises LLC | Borehole mapping tool and methods of mapping boreholes |
Also Published As
Publication number | Publication date |
---|---|
CA2890603C (en) | 2018-12-04 |
EA201590897A8 (en) | 2015-11-30 |
EP2917481A1 (en) | 2015-09-16 |
CN104919137A (en) | 2015-09-16 |
CA2890603A1 (en) | 2014-05-15 |
EA028582B1 (en) | 2017-12-29 |
EP2917481B1 (en) | 2018-02-21 |
CN104919137B (en) | 2018-05-08 |
WO2014071520A1 (en) | 2014-05-15 |
CN104919137A8 (en) | 2017-12-08 |
EP2917481A4 (en) | 2016-11-30 |
NO2970497T3 (en) | 2018-03-24 |
EA201791477A1 (en) | 2018-03-30 |
EA201590897A1 (en) | 2015-08-31 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA2890603C (en) | Downhole electromagnetic telemetry apparatus | |
US11795769B2 (en) | Centralizer for downhole probes | |
US10358906B2 (en) | Downhole probe centralizer | |
US10352111B2 (en) | Drill collar with integrated probe centralizer | |
US11411298B2 (en) | Lower electrode extension for sub-surface electromagnetic telemetry system | |
US10156102B2 (en) | Gap assembly for EM data telemetry | |
US9932776B2 (en) | Pinned electromagnetic telemetry gap sub assembly | |
US10215020B2 (en) | Mud motor with integrated MWD system | |
US10352151B2 (en) | Downhole electronics carrier | |
WO2015168804A1 (en) | Drill string sections with interchangeable couplings |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: EVOLUTION ENGINEERING INC., CANADA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LOGAN, AARON W.;DERKACZ, PATRICK R.;LOGAN, JUSTIN C.;AND OTHERS;REEL/FRAME:035609/0176 Effective date: 20121106 Owner name: EVOLUTION ENGINEERING INC., CANADA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KAZEMI, MOJTABA;REEL/FRAME:035580/0873 Effective date: 20150331 |
|
AS | Assignment |
Owner name: EVOLUTION ENGINEERING INC., CANADA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LOGAN, AARON W.;DERKACZ, PATRICK R.;LOGAN, JUSTIN C.;AND OTHERS;SIGNING DATES FROM 20150728 TO 20150811;REEL/FRAME:036626/0393 |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: FINAL REJECTION MAILED |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |