Patent Publication Number: US-2021164305-A1

Title: Drilling fluid measurements using active gas dilution

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to gas extraction and measurement to determine the composition of gasses produced in wellbore fluid during drilling operations. More particularly, although not necessarily exclusively, this disclosure relates to active, automated control of the dilution of gas samples extracted from wellbore fluid. 
     BACKGROUND 
     A well can include a wellbore drilled through a subterranean formation. Systems to drill such a wellbore use drilling fluid or mud to assist in drilling boreholes into a surface of the earth. Drilling fluid may serve a variety of functions for a drilling system, including, but not limited to, cooling and cleaning a drill bit of the drilling system during operation, allowing a mud motor of the drilling system to convert fluid energy to mechanical energy to provide shaft rotation to the drill bit, and transporting the drill cuttings out of the borehole. The circulation of drilling fluid within a drilling borehole and the interaction between the downhole environment and the drilling fluid may affect or modify the properties of the drilling fluid. The properties of the drilling fluid may be analyzed subsequent to circulation in the borehole to determine the drilling environment of the drilling system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an example of a drilling system including a degasser system for making wellbore drilling fluid measurements using active gas dilution according to at least some aspects of the present disclosure. 
         FIG. 2  is block diagram of the degasser using active gas dilution control in a drilling system according to some aspects of the disclosure. 
         FIG. 3  is block diagram of a computing device for making wellbore drilling fluid measurements using active gas dilution according to some aspects of the disclosure. 
         FIG. 4  is a cross-sectional schematic diagram depicting an example of some of the hardware in a degasser system making wellbore drilling fluid measurements using active gas dilution according to some aspects of the disclosure. 
         FIG. 5  is block diagram of an example of a degasser system using active gas dilution control according to some aspects of the disclosure. 
         FIG. 6  is block diagram of another example of a degasser system using active gas dilution control according to some aspects of the disclosure. 
         FIG. 7  is block diagram of an additional example of a degasser system using active gas dilution control according to some aspects of the disclosure. 
         FIG. 8  is a flowchart of a process for active gas dilution control according to some aspects of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Certain aspects and features relate to a system that improves, and makes more accurate, the compositional measurements made on gasses in wellbore drilling fluid by actively and automatically correcting the flow of a mixture of a sample gas and a carrier gas supplied to detectors used to make the measurements. This control reduces the introduction of contaminants from the measurement environment and allows compositional measurement to be made well above the lower detection limit of the detectors in the analytical equipment being used for the measurements, resulting in higher measurement accuracy. It can also eliminate the need for pressure vents to maintain an appropriate fluid pressure level, since a controller adjusts flow continuously to maintain proper conditions for making measurements. 
     In some examples, a carrier gas source is connected to a flow control device that is coupled to the extractor of a degasser system. The sample gas evolves in the extractor and mixes with the carrier gas, with the combination gas being pushed or pulled to an enclosure. In the enclosure, the amount of combined gasses is measured. The combination gas then continues to the detectors of compositional measurement devices in order to determine composition. The measured flow value is fed to a computing device along with composition information to allow for closed-loop adjustment of the flow value. The computing device uses a stored set point referenced to pressure, temperature, or both, to achieve a flow based on a compositionally corrected flow and the specified number of detectors that consume the gas. The computing device adjusts the flow control device to maintain a constant flow rate within an accurate measurement range of the detectors. 
     In some examples, a system includes a gas flow arrangement including a flow controller, a measurement device, and an extractor, and a computing device in communication with the gas flow arrangement. The computing device includes a non-transitory memory device with instructions that are executable by the computing device so that the computing device mixes the carrier gas with the sample gas extracted from the drilling fluid to produce a combination gas. The computing device then measures a physical state of the combination gas, determines a gas flow rate of the combination gas, and determines a corrected flow rate for the carrier gas based on the physical state of the combination gas. The corrected flow rate is the flow rate that provides for optimized compositional measurements of the combination gas. The computing device adjusts a carrier flow rate of the carrier gas into the drilling fluid to maintain the corrected flow rate of the carrier gas. The physical state of the combination gas can include one or more of its chemical composition, its temperature, or its pressure within the enclosure. 
     In some examples, excess gas is purged from the extractor and the purge flow rate is based at least in part on the corrected flow rate of the carrier gas. A current purge flow rate can also be used to adjust the purge flow rate. Flow rates can be determined based on gas liquid ratio or a direct flow rate value can be used. The purge flow can be used to improve accuracy by providing more precise flow rate control. 
     These illustrative examples are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts. The following sections describe various additional features and examples with reference to the drawings in which like numerals indicate like elements, and directional descriptions are used to describe the illustrative aspects but, like the illustrative aspects, should not be used to limit the present disclosure. 
       FIG. 1  is a schematic diagram of an example of a drilling system including a degasser system for making wellbore drilling fluid measurements using active gas dilution. Drilling system  100  of  FIG. 1  includes a derrick  102  at a surface  104 . The derrick  102  may support components of the drilling system  100 , including a drill string  106 . The drill string  106  may include segmented pipes that may extend below the surface  104  in wellbore  108 . The drill string  106  may transmit drilling fluid (or drilling mud) necessary to operate a drill bit  110 . The weight of the drill string  106  may provide an axial force on the drill bit  110 . The drill string  106  includes downhole components  112  (e.g., a bottom hole assembly, a down hole motor assembly, etc.). Although  FIG. 1  shows the drill bit  110  oriented in a downward direction, the drill bit  110  may be oriented in any direction in the wellbore  108 . 
     The drilling fluid transported through the drill string  106  may be released in the wellbore  108  near the drill bit  110 . The drilling fluid may serve multiple purposes, including cooling the drill bit  110  and other downhole components  112  as they rotate and interface with the surfaces of the wellbore  108  and transmitting hydraulic energy to the downhole components  112  that may be converted to mechanical energy for operation of the drill bit  110 . As the drilling fluid travels through the wellbore  108  back to the surface  104 , the drilling fluid may clean the wellbore  108  and may carry cuttings (e.g., rocks) excavated by the drill bit  110  to the surface  104  to be removed from the wellbore  108 . 
     The drilling system  100  includes a degasser system  114  positioned proximate to the derrick  102  at the surface  104  of the wellbore  108 . The degasser system  114  receives drilling fluid that has been circulated by the drilling system  100  in the wellbore  108 . As the drilling fluid circulates in the wellbore  108  and interfaces with the downhole environment, properties of the wellbore  108  and downhole environment may be transferred to or alter the properties the drilling fluid. For example, the drilling fluid may absorb gases from formations exposed in the wellbore  108  as the drilling fluid interfaces with the surfaces of the wellbore  108  and the downhole environment. The degasser system  114  includes various devices and components for sampling and analyzing drilling fluid from the wellbore  108  to determine the properties of the wellbore  108  based on the gases absorbed during circulation of the drilling fluid in the wellbore  108 . These devices include an extractor and a controller (computing device) to control the various devices in order to provide wellbore drilling fluid measurements using active gas dilution. 
       FIG. 2  is block diagram of the degasser system  114  using active gas dilution control in a drilling system like that shown in  FIG. 1  according to some aspects of the disclosure. The degasser system includes a carrier gas source  202 . The carrier gas may be a noble gas or a gas that is inert to the extraction and detection methodology being used for the wellbore. The carrier gas source is connected to a flow controller  204 . The flow controller may be, as examples, a valve, a mass flow controller or an orifice system that can control flow. The flow controller may have flow measurement capability built in. The flow controller may also include integrated pressure and temperature measurement devices. The flow controller flows carrier gas into the extractor  206  where drilling fluid is processed to sample gas extracted from the drilling fluid. The resulting combination gas is then pumped from or pulled from the extractor by a pump  208 . The pump is connected to a flow measurement device  210  that measures flow as mass or volume and may also measure temperature and pressure using integrated measurement devices. The flow measurement device  210  is connected to a compositional measurement device  212  or multiple measurement devices to determine the chemical composition of the flow. Measurement devices may include analytical instruments, detectors, transducers, or any combination of these. 
     Still referring to  FIG. 2 , the flow measurement and the current or intermediate compositional measurement(s) are sent as signals to a control system, computing device  214 . In  FIG. 2 , arrows such as arrow  216  indicate flow of gasses or liquids, and arrows such as arrow  218  indicate electronic signals. The control system corrects the flow measurement for changes in composition, and in some examples the control system corrects for temperature and pressure. The control system will have a flow set point in some examples referencing a pressure and temperature using a stored look-up table or vector. The control system adjusts the signal to the flow controller connected to the carrier gas source to maintain the flow set point. The set point may be a specified as a gas/liquid (G/L) ratio or a flow value. If a specified G/L ratio is used, the liquid flow rate must be input or measured to provide a reference for the control system. An updated, possibly more accurate compositional measurement can then be made and the set point can be continuously updated for ongoing measurements. 
       FIG. 3  is block diagram of a computing device that in some examples can serve as a control system for making wellbore drilling fluid measurements using active gas dilution according to some aspects of the disclosure. The computing device  214  includes a processing device  302 , a bus  304 , a communication interface  306 , a memory device  308 , a user input device  324 , and a display device  326 . In some examples, some or all of the components shown in  FIG. 3  can be integrated into a single structure, such as a single housing. In other examples, some or all of the components shown in  FIG. 3  can be distributed (e.g., in separate housings) and in communication with each other. The processing device  302  can execute one or more operations for active gas dilution. The processing device  302  can execute instructions stored in the memory device  308  to perform the operations. The processing device  302  can include one processing device or multiple processing devices. Non-limiting examples of the processing device  302  include a field-programmable gate array (“FPGA”), an application-specific integrated circuit (“ASIC”), a processor, a microprocessing device, etc. 
     The processing device  302  shown in  FIG. 3  is communicatively coupled to the memory device  308  via the bus  304 . The non-transitory memory device  308  may include any type of memory device that retains stored information when powered off. Non-limiting examples of the memory device  308  include electrically erasable and programmable read-only memory (“EEPROM”), flash memory, or any other type of non-volatile memory. In some examples, at least some of the memory device  308  can include a non-transitory computer-readable medium from which the processing device  302  can read instructions  309 . A computer-readable medium can include electronic, optical, magnetic, or other storage devices capable of providing the processing device  302  with computer-readable instructions or other program code. Non-limiting examples of a computer-readable medium include (but are not limited to) magnetic disk(s), memory chip(s), read-only memory (ROM), random-access memory (“RAM”), an ASIC, a configured processing device, optical storage, or any other medium from which a computer processing device can read instructions. The instructions can include processing device-specific instructions generated by a compiler or an interpreter from code written in any suitable computer-programming language, including, for example, C, C++, C#, etc. 
     Still referring to the example of  FIG. 3 , the memory device  308  includes stored values for flow rates  320 . The memory device  308  includes computer program code instructions  309  for controlling gas dilution. Memory device  308  in this example includes stored temperatures  314  and stored pressures  316 . Memory device  308  also includes the stored, current flow set point  312  and a stored table  310  of flow set points referenced to temperatures and pressures. 
     In some examples, the computing device  214  includes a communication interface  306 . The communication interface  306  can represent one or more components that facilitate a network connection or otherwise facilitate communication between electronic devices. Examples include, but are not limited to, wired interfaces such as Ethernet, USB, IEEE 1394, and/or wireless interfaces such as IEEE 802.11, Bluetooth, near-field communication (NFC) interfaces, RFID interfaces, or radio interfaces for accessing cellular telephone networks (e.g., transceiver/antenna for accessing a CDMA, GSM, UMTS, or other mobile communications network). 
     In some examples, the computing device  214  includes a user input device  324 . The user input device  324  can represent one or more components used to input data. Examples of the user input device  324  can include a keyboard, mouse, touchpad, button, or touch-screen display, etc. In some examples, the computing device  214  includes a display device  326 . Examples of the display device  326  can include a liquid-crystal display (LCD), a television, a computer monitor, a touch-screen display, etc. In some examples, the user input device  324  and the display device  326  can be a single device, such as a touch-screen display. 
       FIG. 4  is a cross-sectional schematic diagram depicting an example of some of the hardware in a degasser system making wellbore drilling fluid measurements using active gas dilution according to some aspects of the disclosure. The sample degasser system  400  includes an extractor  401  with includes a tank  402  in which drilling fluid may be located after entering through a fluid inlet valve  404  and before leaving through a fluid outlet valve  406  to allow the extractor  401  to maintain a constant volume of drilling fluid in the tank  402 . The extractor  401  also includes a carrier gas intake valve  408 . The carrier gas intake valve  408  may allow the carrier gas to flow directly into the tank  402 . The carrier gas intake valve  408  is coupled to the flow controller  204  by a fluid line  410  that may transport the carrier gas from the flow controller  204  to the carrier gas intake valve  408 . The extractor  401  is coupled to the pump  208  by the line  412 . Flow controller  204  is coupled to a carrier gas source by line  413 . 
     Still referring to  FIG. 4 , the pump  208  extracts the gases from the drilling fluid in the extractor  401  at an extraction rate that may be adjusted either manually or automatically, in concert with the rate of injection of the carrier gas into the extractor, to control the dilution of the gases. The gas extracted by pump  208  is a combination gas including the carrier gas and sample gas from the drilling fluid. Computing device  214  serves as a control system and is electrically connected to flow controller  204 . Computing device  214  is also connected to measurement device  212 , which may include detectors, analytical instruments, or both, to provide compositional measurements of the gas being pumped from the extractor  401 . Gasses exit through port  416  after measurements take place. 
       FIG. 5  is block diagram of another example of a degasser system using active gas dilution control according to some aspects of the disclosure. The main difference between degasser system  114 , previously discussed, and degasser system  500  shown in  FIG. 5  is that the determination of a corrected flow rate does not take into account compositional measurements. The physical state of the combination gas is based on flow, temperature, pressure, or a combination of these. The degasser system  500  includes the carrier gas source  202  and the flow controller  204 . The flow controller may be, as examples, a valve, a mass flow controller or an orifice system that can control flow. The flow controller may have flow measurement capability built in. The flow controller may also include integrated pressure and temperature measurement devices. The flow controller flows carrier gas into the extractor  206  where drilling fluid is processed to sample gas from the drilling fluid. The resulting combination gas is then pumped from or pulled from the extractor by pump  208 . The pump is connected to a flow measurement device  510  that measures flow as mass or volume and also measures temperature and pressure using integrated measurement devices. 
     Still referring to  FIG. 5 , the flow, temperature, and pressure measurements are sent as signals to a control system, computing device  514 . The control system corrects the flow measurement for changes in temperature and pressure. The control system will have a flow set point in some examples, referencing pressure and temperature using a stored look-up table or vector. The control system adjusts the signal to the flow controller connected to the carrier gas source to maintain the flow set point. 
       FIG. 6  is block diagram of another example of a degasser system using active gas dilution control according to some aspects of the disclosure. The degasser system  600  includes the carrier gas source  202  and the flow controller  204 . The flow controller may be, as examples, a valve, a mass flow controller or an orifice system that can control flow. The flow controller may have flow measurement capability built in. The flow controller may also include integrated pressure and temperature measurement devices. The flow controller flows carrier gas into the extractor  606  where drilling fluid is processed to sample gas from the drilling fluid. Extractor  606  includes an excess purge device  608 . The flow of the purge is controlled by purge flow controller  610 . The combination gas from extractor  606  is pumped from or pulled from the extractor by pump  208 . The pump is connected to a flow measurement device  210  that measures flow as mass or volume and may also measure temperature and pressure using integrated measurement devices. 
     Still referring to  FIG. 6 , degasser system  600  includes a flow measurement device  612  to measure the purge flow. Computing device  614  corrects the flow measurement for changes in composition, and in some examples the control system corrects for temperature and pressure. The control system will have a flow set point in some examples, referencing a pressure and temperature using a stored look-up table or vector. The control system adjusts the signal to the flow controller connected to the carrier gas source to maintain the flow set point. In system  600  however, the computing device also measures purge flow using flow measurement device  612  and controls purge flow according to a purge flow set point using purge flow controller  610 . The control system can use the purge flow measurement and the corrected flow rate for the carrier gas to manage the amount of purge flow using purge flow controller  610  in order to achieve more precise control for composition measurement. 
       FIG. 7  is block diagram of an additional example of a degasser system using active gas dilution control according to some aspects of the disclosure. The degasser system  700  includes the carrier gas source  202  and the flow controller  204 . The flow controller may be, as examples, a valve, a mass flow controller or an orifice system that can control flow. The flow controller may have flow measurement capability built in. The flow controller may also include integrated pressure and temperature measurement devices. The flow controller flows carrier gas into the extractor  606  where drilling fluid is processed to sample gas from the drilling fluid. Extractor  606  includes an excess purge device  608 . The flow of the purge is controlled by purge flow controller  610 . The combination gas from extractor  606  is pumped from or pulled from the extractor by pump  208 . The pump is connected to a flow measurement device  210  that measures flow as mass or volume and may also measure temperature and pressure using integrated measurement devices. 
     Still referring to  FIG. 7 , computing device  714  corrects the flow measurement for changes in composition, and in some examples the control system corrects for temperature and pressure. The control system will have a flow set point in some examples, referencing a pressure and temperature using a stored look-up table or vector. The control system adjusts the signal to the flow controller connected to the carrier gas source to maintain the flow set point. In system  700  the computing device also controls purge flow according to a purge flow set point using purge flow controller  610 . The control system relies on flow measurement from flow measurement device  210  and the corrected flow rate for the carrier gas to manage the amount of purge flow using purge flow controller  610  in order to achieve more precise control for composition measurement. System  700  does not have a separate purge flow measurement device. 
       FIG. 8  is a flowchart of a process  800  for active gas dilution control according to some aspects of the disclosure. The process will be described, as an example, referencing devices in  FIG. 2 ,  FIG. 3 , and  FIG. 6 . At block  802 , carrier gas is next with sample gas extracted from the drilling fluid to produce a combination gas. At block  804 , processing device  302  measures the physical state of the combination gas. This physical state can include the composition, the pressure, the temperature, or combination of such properties. For example, processing device  302  can measure the composition using compositional measurement device  212 . At this stage of the processes  800 , the compositional measurement performed is primarily to obtain data for adjusting the flow rate rather than to obtain an accurate picture of the drilling environment. At block  806 , processing device  302  measures the flow rate of the combination gas into the drilling fluid, for example, using flow measurement device  210 . The flow rate can be expressed as a numerical rate of flow or as a gas/liquid ratio. 
     Still referring to  FIG. 8 , at block  808 , excess gas is optionally purged from the extractor, for example using excess purge device  608 . At block  810 , the flow rate of the excess gas is measured by processing device  302 . At block  812 , the flow rate of the excess gas is adjusted by processing device  302 . At block  814 , processing device  302  determines a corrected flow rate using a set point based on temperature, pressure, or both. The set point may be determined from stored table  310 . At block  816 , processing device  302  adjusts the flow rate of the carrier gas from carrier gas source  202  into the drilling fluid to maintain the determined, corrected flow rate. At block  818 , accurate compositional measurements are made for use in analyzing the drilling fluid and the drilling environment. The process  800  can repeat continuously to maintain a set point flow rate for accurate ongoing measurements. 
     In some aspects, drilling fluid measurements using active gas dilution can be provided according to one or more of the following examples. As used below, any reference to a series of examples is to be understood as a reference to each of those examples disjunctively (e.g., “Examples 1-4” is to be understood as “Examples 1, 2, 3, or 4”). 
     Example 1. A system includes a gas flow subsystem including a measurement device and an extractor and a computing device in communication with the gas flow subsystem. The computing device includes a non-transitory memory device further including instructions that are executable by the computing device to cause the computing device to perform operations. The operations include injecting a carrier gas into the extractor to mix with a sample gas extracted from drilling fluid and produce a combination gas, acquiring, using the measuring device, a physical state of the combination gas, determining a gas flow rate of the combination gas from the extractor, and determining, based on the gas flow rate and the physical state of the combination gas, a corrected flow rate for the carrier gas that is usable for making optimized compositional measurements of the combination gas. The operations further include adjusting a carrier flow rate of the carrier gas to maintain the corrected flow rate of the carrier gas into the extractor. 
     Example 2. The system of example 1, wherein the physical state of the combination gas includes a chemical composition of the combination gas. 
     Example 3. The system of example(s) 1-2, wherein the physical state of the combination gas includes at least one of a temperature or a pressure of the combination gas. 
     Example 4. The system of example(s) 1-3, wherein the operation of adjusting the carrier flow rate of the carrier gas is based on a set point referenced to a temperature and a pressure. 
     Example 5. The system of example(s) 1-4, wherein the operations further include adjusting a purge flow controller to set a purge flow rate of excess gas from the extractor based at least in part on the corrected flow rate of the carrier gas. 
     Example 6. The system of example(s) 1-5, wherein the operations further include determining the purge flow rate of the excess gas. 
     Example 7. The system of example(s) 1-6, wherein at least one operation of determining the purge flow rate or determining the gas flow rate is based on a gas liquid ratio. 
     Example 8. A method includes injecting, by a processing device using a flow control device, a carrier gas into an extractor to mix with a sample gas extracted from drilling fluid and produce a combination gas and acquiring, by the processing device using a measuring device, a physical state of the combination gas. The method further includes determining, by the processing device, a gas flow rate of the combination gas from the extractor, determining, by the processing device and based on the gas flow rate and the physical state of the combination gas, a corrected flow rate for the carrier gas that is usable for making optimized compositional measurements of the combination gas, and adjusting, by the processing device, a carrier flow rate of the carrier gas to maintain the corrected flow rate of the carrier gas into the extractor. 
     Example 9. The method of example 8, wherein the physical state of the combination gas includes a chemical composition of the combination gas. 
     Example 10. The method of example(s) 8-9, wherein the physical state of the combination gas includes at least one of a temperature or a pressure of the combination gas. 
     Example 11. The method of example(s) 8-10, wherein adjusting the carrier flow rate of the carrier gas is based on a set point referenced to a temperature and a pressure. 
     Example 12. The method of example(s) 8-11 further includes adjusting a purge flow controller to set a purge flow rate of excess gas from the extractor based at least in part on the corrected flow rate of the carrier gas. 
     Example 13. The method of example(s) 8-12 further includes determining the purge flow rate of the excess gas. 
     Example 14. The method of example(s) 8-13 wherein at least one of determining the purge flow rate or determining the gas flow rate is based on a gas liquid ratio. 
     Example 15. A non-transitory computer-readable medium that includes instructions that are executable by a processing device for causing the processing device to perform a method. The method includes injecting a carrier gas into an extractor to mix with a sample gas extracted from drilling fluid and produce a combination gas, acquiring a physical state of the combination gas, and determining a gas flow rate of the combination gas. The method further includes determining, based on the gas flow rate and the physical state of the combination gas, a corrected flow rate for the carrier gas that is usable for making optimized compositional measurements of the combination gas, and adjusting a carrier flow rate of the carrier gas into the extractor to maintain the corrected flow rate of the carrier gas. 
     Example 16. The non-transitory computer-readable medium of example 15, wherein the physical state of the combination gas includes a chemical composition of the combination gas. 
     Example 17. The non-transitory computer-readable medium of example(s) 15-16, wherein the physical state of the combination gas includes at least one of a temperature or a pressure of the combination gas. 
     Example 18. The non-transitory computer-readable medium of example(s) 15-17, wherein adjusting the carrier flow rate of the carrier gas is based on a set point referenced to a temperature and a pressure. 
     Example 19. The non-transitory computer-readable medium of example(s) 15-18, wherein the method further includes adjusting a purge flow controller to set a purge flow rate of excess gas from the extractor based at least in part on the corrected flow rate of the carrier gas. 
     Example 20. The non-transitory computer-readable medium of example(s) 15-19, wherein determining at least one of the gas flow rate or the purge flow rate is based on a gas liquid ratio. 
     The foregoing description of certain examples, including illustrated examples, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art without departing from the scope of the disclosure.