CN100513742C - Electromagnetic telemetering method and system of measuring by bit - Google Patents

Abstract

The invention provides an electromagnetic telemetry method and system for measurement while drilling, wherein the data measured by the downhole sensor is converted into an electromagnetic signal and then output; the electromagnetic signal is transmitted to the ground by using the drill string and the formation as a medium; the electromagnetic signal is received Electromagnetic signals in the medium and process the received electrical signals. The conversion of the data measured by the downhole sensor into an electromagnetic signal and then the output refers to: using the sensor to measure the geological parameters of the wellbore trajectory and the formation position where the drill bit is located, and performing carrier frequency modulation and power amplification processing on the measured data , transmit and output the processed signal to overcome the problems existing in the existing telemetry technology. Widely used in special process wells or conventional drilling with various media as drilling fluid for measurement while drilling. In the drilling project, the drilling trajectory can be drilled more accurately according to the engineering design requirements, and the formation information can be grasped more timely and accurately, and the measurement data can be transmitted to the ground in real time and accurately.

Description

An electromagnetic telemetry method and system for measurement while drilling

technical field

The present invention relates to the technique of using electromagnetic telemetry to transmit downhole data in the measurement-while-drilling or non-measurement-while-drilling drilling equipment of petroleum, mining, geological exploration, etc., specifically speaking, an electromagnetic telemetry method and system for measurement-while-drilling.

Background technique

At present, in drilling projects such as petroleum, mining, and geological exploration, in order to make the drilling trajectory more accurate and drill according to the engineering design requirements, and to grasp the stratum information more timely and accurately, it is necessary to install the directional sensor and the sensor for collecting geological information. The location of the drill bit. These sensors measure downhole with the drilling of the drilling rig, and at the same time, the data collected by the sensors are transmitted to the ground in real time, so that engineers and technicians can keep abreast of the trajectory of the wellbore and changes in formation information. This process of transmitting downhole measurement information is often referred to as "telemetry."

There are generally two methods for telemetry downhole measurement information in drilling engineering, one is "wired telemetry method"; the other is "mud pulse telemetry method"; "wired telemetry method" is to connect the lower end of an armored single-core cable Through the channel of the drill string, it is put into the downhole drill collar, and the data obtained by the measuring instrument is transmitted to the ground by this armored single-core cable. But this method cannot be used in rotary drilling and wells with inclination angles greater than 45 degrees. Because the cable will be twisted if the drill string rotates in the passage of the drill string, and when the inclination angle is greater than 45 degrees, it will be difficult for the instrument to be lowered to the bottom of the well by its own weight.

Regarding the "mud pulse telemetry method", it uses a pulse generator installed in the drill collar to generate pressure waves in the mud in the drill string channel, and uses this pressure wave as a carrier to transmit data. This telemetry method can only be used in drilling construction with ordinary mud as the medium. If it is used in underbalanced drilling, it will not be able to transmit downhole data, because the drilling fluid (medium) in underbalanced drilling is gas or foam mud. Gases and foamy slurries are compressible, and the pressure pulses generated in this medium can be severely deformed so that the receiving sensor cannot pick up the signal correctly. Therefore, in the drilling project, in order to make the drilling trajectory more accurate and drill according to the engineering design requirements, and to grasp the formation information more timely and accurately, it is necessary to install the orientation sensor and the sensor for collecting geological information near the drill bit for measurement while drilling. At the same time, the measurement data should be transmitted to the ground in real time. How to solve the problem of real-time transmission of downhole measurement data to the ground is a key issue.

Contents of the invention

The content of the present invention is to provide an electromagnetic telemetry method and system for measuring while drilling, so as to overcome the problems existing in the existing telemetry technology. It is widely used in special process wells (such as directional drilling, horizontal drilling, underbalanced drilling, etc.) or conventional drilling for measurement while drilling with various media as drilling fluid. In the drilling project, the drilling trajectory can be drilled more accurately according to the engineering design requirements, and the formation information can be grasped more timely and accurately, and the measurement data can be transmitted to the ground in real time and accurately.

The technical solution of the present invention is: an electromagnetic telemetry method for measuring while drilling, which includes:

The electromagnetic telemetry transmission system is composed of sensors and instrument sub-sections, downhole transmitting devices, drill strings, signal cables, ground receiving devices, grounding electrodes and formations; the bottom-hole data is measured by sensors and the sensors in the instrument sub-sections; the measured Carrier frequency modulation and power amplification are performed on the data; the processed signal is generated and output by the transmitting coil and the transmitting circuit in the downhole transmitting device; the carrier frequency electromagnetic signal is transmitted by using the drill string and the formation as the medium The signal is transmitted to the ground; the ground receiving device is used to receive the carrier frequency electromagnetic signal in the medium and process the received carrier frequency electromagnetic signal.

The transmitting coil is equipped with a ceramic material insulating ring or a high-temperature epoxy resin insulating ring; the carrier-frequency electromagnetic signal is a carrier-frequency current and a carrier-frequency electromagnetic wave; through a cable, one end of the ground receiving device is connected to the ground electrode, and the other end is connected to the wellbore casing As well as a point on the well platform or derrick. The grounding electrode is 5-100 meters away from the platform of the derrick, and grounding conductive fluid needs to be poured into the formation around the grounding electrode.

The ground receiving device includes a current sensor and an electromagnetic wave sensor. The use of the ground receiving device to receive the carrier frequency electromagnetic signal in the medium and process the received carrier frequency electromagnetic signal refers to: using a current sensor, an electromagnetic wave sensor To receive the electromagnetic signal transmitted from the medium, the current sensor receives the carrier frequency current flowing through the drill string and the formation, and the electromagnetic wave sensor receives the carrier frequency electromagnetic wave passing through the formation.

The processing of the received carrier-frequency electromagnetic signal includes pre-amplification, signal monitoring switching, band-pass filtering, automatic gain control, demodulation, signal detection, and digital filtering of the received carrier-frequency electromagnetic signal. The carrier frequency current is transmitted through the carrier frequency current loop composed of drill string, drill bit, formation, ground receiving device, signal cable and ground electrode.

The carrier frequency electromagnetic wave is transmitted through the carrier frequency electromagnetic wave channel formed by the formation and the ground receiving device.

The present invention also provides an electromagnetic telemetry system for measurement while drilling, wherein the electromagnetic telemetry transmission system is composed of sensors, instrument sub-sections, downhole transmitting devices, drill strings, signal cables, ground receiving devices, grounding electrodes and formations; The drill string and the formation constitute an electromagnetic channel. The sensor in the sensor and the instrument sub-section transmits the measured bottom-hole data to the downhole transmitter; the downhole transmitter modulates the bottom-hole data into a carrier frequency signal and transmits it to the The electromagnetic channel; the ground receiving device receives the carrier-frequency electromagnetic signal in the electromagnetic channel and processes the received signal; the carrier-frequency electromagnetic signal is a carrier-frequency current and a carrier-frequency electromagnetic wave.

The downhole transmitting device has a transmitting coil and a transmitting circuit, and the transmitting coil is equipped with an insulating ring made of ceramic material or high-temperature epoxy resin; the ground receiving device includes a current sensor and an electromagnetic wave sensor, a preamplifier, Signal detection switch, band-pass filter, automatic gain controller, FSK demodulator, signal detector, digital filter, data processing device and data display device; the current sensor receives the carrier frequency flowing through the drill string and formation current, the electromagnetic wave sensor receives the carrier frequency electromagnetic wave passing through the formation.

Described transmitting circuit is made up of sensor data interface, FSK modulator, carrier frequency signal generator, power amplifier; Described sensor data interface receives the data from sensor according to agreed communication rule; By described carrier frequency signal generator Produce carrier frequency signal; Described FSK modulator uses data modulation carrier frequency signal according to FSK modulation mode; Modulated carrier frequency signal is sent into described power amplifier and amplified; The signal through power amplification is sent into signal transmitting coil, by The transmitting coil induces a carrier frequency current or voltage on the drill string. The current sensor and the electromagnetic wave sensor constitute a sensor group. Both ends of the downhole launching device are tapered threads made according to petroleum industry standards, the upper part of the tapered thread is connected to the drill string, and the lower part of the tapered thread is connected to the sensor and the instrument pup joint.

The sensor and the short section of the instrument are connected to the data input cable of the downhole launching device through the cable plug; the data input cable is protected by the cable guard ring and the cable guard ring. The transmitting coil is an annular body made of magnetically permeable material, and a coil is wound on the annular body.

The beneficial effect of the present invention is that, by providing an electromagnetic telemetry method and system for measuring while drilling, it is used to overcome the problems existing in the existing telemetry technology. It is widely used in special process wells (such as directional drilling, horizontal drilling, underbalanced drilling, etc.) or conventional drilling for measurement while drilling with various media as drilling fluid. In the drilling project, the drilling trajectory can be drilled more accurately according to the engineering design requirements, and the formation information can be grasped more timely and accurately, and the measurement data can be transmitted to the ground in real time and accurately.

Description of drawings

Fig. 1 is the schematic diagram of the electromagnetic telemetry system of measuring while drilling of the present invention;

Fig. 2 is a schematic structural view of a sub-section of a launching device according to the present invention;

Fig. 3 is the functional block diagram of the electromagnetic telemetry system of the measurement while drilling of the present invention;

Fig. 4 is a schematic diagram of the connection between the sub-section of the transmitting device and the sub-section of the sensor and instrument according to the present invention.

Detailed ways

Now combine (Fig. 1) and (Fig. 2) to describe the method of "measurement while drilling by electromagnetic telemetry". The main core of this method is to use current and electromagnetic waves as the carrier, and use the drill string and formation as the medium to transmit the downhole data to the ground. According to the classical electromagnetic field theory, the stratum exhibits different dielectric properties under different conditions, which can be expressed mathematically as

a. $\frac{\mathrm{\&sigma;}}{\mathrm{\&omega;\&epsiv;}}<\frac{1}{100}$ The medium acts as a dielectric (insulation)

b. $\frac{1}{100}<\frac{\mathrm{\&sigma;}}{\mathrm{\&omega;\&epsiv;}}<100$ The medium behaves as a semi-dielectric (semi-insulating)

c. $\frac{\mathrm{\&sigma;}}{\mathrm{\&omega;\&epsiv;}}>100$ The medium behaves as a conductor

in:

σ-conductivity;

ε-dielectric constant;

ω - the angular frequency of the electromagnetic field in the medium;

Under normal circumstances, the stratum is mostly shown as a semi-dielectric (semi-insulating) property, just like a resistance, so the downhole transmitter 8, the drill string 7, the cable 3, the ground receiver 4, the ground electrode 5, the formation 29, the drill bit 10 and the sensor It forms a series closed circuit with the shell of the short joint 9 of the instrument (see Figure 1). Therefore, the carrier frequency current 6 sent by the downhole transmitting device 8 will flow in this closed loop, and the downhole data modulated on the carrier frequency current will be transmitted to the ground to be received by the ground receiving device.

If the formation resistance is very large, the carrier frequency current 6 in the loop will become very small at this time, and now the downhole launcher 8, the drill string 7, the drill bit 10 and the sensor and the instrument sub-joint 9 just constitute an electric circuit with unequal arm lengths. The dipole radiates electromagnetic waves to the formation, and the electromagnetic wave passing through the formation 29 will be received by the TM wave sensor in the ground receiving device 4 .

A kind of electromagnetic telemetry method and system (see Fig. 1) that the present invention is used for measuring while drilling, is made up of downhole transmitting device 8, drill string 7, stratum 29, ground receiving device 4, signal cable 3, grounding electrode 5 to form electromagnetic telemetry transmission system. The current 6 and electromagnetic wave 11 of a certain frequency (also called carrier frequency current or carrier frequency electromagnetic wave) are sent out by the downhole transmitting device 8, transmitted to the ground through the electromagnetic channel formed by the drill string 7 and the formation 29, and then transmitted by the ground receiving device (4 ) reception, thereby completing real-time communication of downhole data.

The characteristics of the downhole transmitting device 8 are: the transmitted (see FIG. 1 ) carrier frequency current 6 or carrier frequency electromagnetic wave 11 is generated by (see FIG. 2 ) the transmitting circuit 16 and the transmitting coil 14 . The carrier frequency current 6 or carrier frequency electromagnetic wave 11 (TM wave) generated in this way passes through the drill string, the drill bit, and the formation to reach the ground.

The method that described carrier-frequency current or carrier-frequency electromagnetic wave produces, the channel characteristic that underground signal is transmitted to ground is (seeing Fig. 1):

① The drill string 7, the drill bit 10, the formation 29, the ground receiving device 4, the signal cable 3, and the ground electrode 5 form a carrier frequency current loop;

② In the formation 29, the ground receiving device 4 constitutes a carrier frequency electromagnetic wave (TM wave) channel.

The method of receiving the signal is completed by the ground receiving device, and the ground receiving device has a current receiving sensor and an electromagnetic wave (TM wave) receiving sensor.

The feature of realizing the electromagnetic telemetry method system composition is: see (Fig. 3) principle block diagram, this system mainly is made up of two parts: downhole transmitting device 18; Ground receiving device 22.

The characteristics of the principle of formation of the downhole transmitting device 18 are (see FIG. 3 ): the downhole transmitting device 18 is composed of a sensor data interface, a carrier frequency signal generator, FSK modulation, power amplification, a signal transmitter and a transmitting electrode (antenna) 19.

The feature of ground receiving device 22 composition principle is: (see Fig. 3), ground receiving device 22 is by sensor group 21, preamplification, signal detection switch, band-pass filtering, automatic gain control, FSK demodulation, signal detection, digital Filtering, data processing and data display and other components.

The characteristics of the composition of the sensor group 21 are (see FIG. 3 ): the sensor group 21 is composed of a current receiving sensor and an electromagnetic wave (TM wave) receiving sensor.

The mechanical combination feature of the downhole transmitter is (seeing Fig. 2): the transmitter circuit 16 and the transmitter coil 14 are installed in the downhole transmitter 8, they are connected by the cable 15, and a ceramic material or high-temperature epoxy resin is installed outside the transmitter coil 14. The insulating ring 13 made; in addition, the two ends of the launcher pup joint are tapered threads made according to the petroleum industry standard, the upper part of the tapered thread 12 is connected to the drill string 7, and the lower part of the tapered thread 25 (see Figure 4) Connect the sensor and instrument short section 9.

The mechanical combination (seeing Fig. 3) of described downhole transmitting device, the feature of its transmitting circuit 16 is (seeing Fig. 2): transmitting circuit 16 is made up of sensor data interface, carrier frequency signal generator, FSK modulation, each function such as power amplification Block circuit composition.

The characteristics of the mechanical connection and data signal connection between the downhole launcher 8 and the sensor and instrument subsection 9 are (see Figure 4): after the downhole launcher 8 is connected with the sensor and instrument subsection 9 through a tapered thread 25, the sensor and instrument The data sent by the short section 9 will be connected with the data input cable 17 of the downhole transmitter 8 through the cable plug 24 . The data input cables are protected by cable grommets 23, 28 to prevent erosion of mud and cuttings.

In the method for receiving downhole signals on the ground, the ground receiving device is electrically connected to the drill string and the ground electrode (see Figure 1): one end of the cable 3 drawn from the ground receiving device is connected to the ground electrode 5, and the other end is connected to the wellbore casing 2 As well as a point on the well platform or derrick.

The characteristic of the transmitting coil 14 is that the transmitting coil 14 is an annular body made of magnetically permeable material, and a coil is wound on the annular body.

The following describes the specific process of electromagnetic telemetry transmission and reception:

1. Launch process (see Figure 3):

The data interface receives the data from the sensor and the short section of the instrument according to the agreed communication rules;

A carrier frequency signal is generated by a carrier frequency signal generator;

The data from the data interface modulates the carrier frequency signal according to the modulation mode;

The modulated carrier frequency signal is sent to the power amplifier for amplification;

The amplified signal is sent to the signal transmitter (transmitting coil), also known as the transmitting electrode, and the carrier frequency current or voltage is induced on the drill string by the transmitting coil.

Second, the transmission process (see Figure 1):

If the formation resistivity is not high, the carrier frequency current forms a closed loop in the downhole transmitter 8, the drill string 7, the cable 3, the ground receiver 4, the ground electrode 5, the formation 29, the drill bit 10 and the shell of the sensor and the instrument nipple 9 middle flow;

If the formation resistivity is very high, the carrier frequency current in the drill string will become very small, and the carrier frequency electromagnetic wave radiated by the downhole transmitter 8 plays a major role in transmission.

3. The receiving process (see Figure 3):

There are two sensors in the ground receiving device, one is a current sensor, and the other is an electromagnetic wave sensor (TM wave) sensor. Their functions are: the current sensor can receive the carrier frequency current flowing through the drill string and the formation, and the TM wave sensor can receive the carrier frequency electromagnetic wave passing through the formation;

The weak signals received by the two sensors are respectively sent to the preamplifier for amplification, and then sent to the signal detection switch. After comparison, the stronger signal is sent to the band-pass filter;

After the signal is band-pass filtered, the noise signal outside the bandwidth is removed so that the signal can be preliminarily sorted out;

The filtered signal is sent to the automatic gain control. The purpose of using the automatic gain control is to prevent the top-cutting distortion of the signal caused by the signal being too large;

The signal is demodulated by FSK, and then the data signal is recovered after detection;

In the process of signal transmission, it may be interfered with the same frequency as the carrier frequency signal, and the data signal recovered after demodulation and detection may be incomplete, so the data must be further shaped by digital filtering;

The data after digital filtering is sent to the display screen for display after relevant processing.

The embodiment that the present invention applies is:

1) (See Figure 4) First connect the launch pup 8 with the sensor and instrument pup 9 through the thread 25; then connect the cable of the sensor and the instrument pup with the cable of the launch pup through the plug 24; and then install Cable grommets 23, 28 enclose cables and plugs.

2) Connect the upper end of the launch nipple 8 to the drill string.

3) Install the drill bit at the lower end of the sensor and instrument sub-section 9, and install the drill bit at the lower end of the sensor and instrument sub-section if other instruments or tools need to be installed.

4) (See Fig. 1) After the drill string is lowered to the bottom of the well, the cable 3 is connected to the wellbore casing 2 and a certain point on the well platform or derrick.

5) (see FIG. 1 ) drive the ground electrode 5 into the ground, and the ground electrode is about 5-100 meters away from the platform of the derrick 1 .

6) Pour grounding conductive liquid, such as saturated saline, around the grounding electrode.

7) (See Figure 1) Connect the cable 3 to the ground receiving device and the ground electrode.

8) Turn on the power of the ground receiving device to receive downhole signals.

The beneficial effect of the present invention is that, by providing an electromagnetic telemetry method and system for measuring while drilling, it is used to overcome the problems existing in the existing telemetry technology. It is widely used in special process wells (such as directional drilling, horizontal drilling, underbalanced drilling, etc.) or conventional drilling for measurement while drilling with various media as drilling fluid. In the drilling project, the drilling trajectory can be drilled more accurately according to the engineering design requirements, and the formation information can be grasped more timely and accurately, and the measurement data can be transmitted to the ground in real time and accurately.

The above specific embodiments are only used to illustrate the present invention rather than limit the present invention.

Claims (9)

1. the em telemetry method of a measurement while drilling, comprising:

Utilize sensor and instrument pipe nipple (9), silo launcher (8), drill string (7), signal cable (3), ground receiving wastewater facility (4), earthing electrode (5) and stratum (29) formation em telemetry transmission system;

Adopt the sensor in sensor and the instrument pipe nipple (9) that the shaft bottom data are measured;

The data that record are carried out the processing of carrier frequency modulation, power amplification;

Transmitting coil and the radiating circuit of signal after handling in silo launcher generated carrier frequency electromagnetic signal and output; Utilize drill string and stratum as medium with described carrier frequency electromagnetic signal transmission to ground;

Utilize ground receiving wastewater facility to receive the carrier frequency electromagnetic signal in the described medium and the carrier frequency electromagnetic signal that receives handled;

Wherein:

Described transmitting coil is equipped with ceramic materials dead ring or High temp. epoxy resins dead ring outward;

Described carrier frequency electromagnetic signal is carrier frequency electric current and carrier frequency electromagnetic wave;

By cable (3), ground receiving wastewater facility (4) one ends connect earthing electrode (5), and certain is a bit on another termination wellbore casing (2) and raised platform around a well or the derrick;

Earthing electrode is apart from the platform 5-100 rice of derrick (1), and need are to perfusion ground connection conduction liquid in earthing electrode (5) stratum on every side;

Described ground receiving wastewater facility comprises current sensor, electromagnetic sensor, describedly utilize ground receiving wastewater facility to receive the carrier frequency electromagnetic signal in the described medium and the carrier frequency electromagnetic signal that receives handled to be meant: adopt current sensor, electromagnetic sensor that the electromagnetic signal that transmits from described medium is received, current sensor receives the carrier frequency electric current that flows through drill string and stratum, and electromagnetic sensor receives the carrier frequency electromagnetic wave that passes the stratum.

2. method according to claim 1, it is characterized in that, the carrier frequency electromagnetic signal that receives is handled comprised that the carrier frequency electromagnetic signal received of butt joint carries out the processing of preposition amplification, signal monitoring switching, bandpass filtering, automatic gain control, demodulation, signal demodulator, digital filtering.

3. method according to claim 1 and 2, it is characterized in that described carrier frequency electric current transmits by the carrier frequency current loop that is made of drill string (7), drill bit (10), stratum (29), ground receiving wastewater facility (4), signal cable (3), earthing electrode (5);

Described carrier frequency electromagnetic wave transmits by the carrier frequency electromagnetic wave passage that is made of stratum (29), ground receiving wastewater facility (4).

4. the electromagnetic remote metering system of a measurement while drilling, it is characterized in that, by sensor and instrument pipe nipple (9), silo launcher (8), drill string (7), signal cable (3), ground receiving wastewater facility (4), earthing electrode (5) and stratum (29) formation em telemetry transmission system; Constitute electromagnetic signal channel by described drill string (7) and stratum (29); Wherein:

Sensor in described sensor and the instrument pipe nipple (9) sends the shaft bottom data that record to described silo launcher; Described silo launcher is modulated into CF signal with the shaft bottom data and launches after power amplification and outputs to described electromagnetic signal channel; Described ground receiving wastewater facility receives the carrier frequency electromagnetic signal in the described electromagnetic signal channel and handles to the received signal; Described carrier frequency electromagnetic signal is carrier frequency electric current and carrier frequency electromagnetic wave;

Described silo launcher has transmitting coil (14) and radiating circuit (16), the outer dead ring made from ceramic materials or High temp. epoxy resins (13) that is equipped with of this transmitting coil (14);

By cable (3), ground receiving wastewater facility (4) one ends connect earthing electrode (5), and certain is a bit on another termination wellbore casing (2) and raised platform around a well or the derrick;

Described ground receiving wastewater facility (4) comprises current sensor and electromagnetic sensor, preamplifier, signal detection switch, bandpass filter, automatic gain controller, fsk demodulator, sound detector, digital filter, data processing equipment and data presentation device; Described current sensor receives the carrier frequency electric current that flows through drill string and stratum, and described electromagnetic sensor receives the carrier frequency electromagnetic wave that passes the stratum;

Earthing electrode is apart from the platform 5-100 rice of derrick (1), and need are to perfusion ground connection conduction liquid in earthing electrode (5) stratum on every side.

5. system according to claim 4 is characterized in that, described radiating circuit is made of sensor data interface, FSK modulator, CF signal generator, power amplifier;

Described sensor data interface communication rule by appointment receives the data from sensor; Produce CF signal by described CF signal generator; Described FSK modulator is according to FSK modulation system data modulated carriers signal; CF signal after the modulation is sent into described power amplifier and is amplified; Send into the signal transmitting coil through the signal of power amplification, on drill string, induce the carrier frequency curtage by transmitting coil.

6. system according to claim 4 is characterized in that, described current sensor and electromagnetic sensor constitute sensor groups (21).

7. system according to claim 6, it is characterized in that, the two ends of silo launcher are the tapered thread of manufacturing according to the petroleum industry standard, and top tapered thread (12) connects drill string (7), and lower part tapered thread (25) connects sensor and instrument pipe nipple (9).

8. system according to claim 7 is characterized in that, sensor and instrument pipe nipple (9) are connected with the data input cables (17) of silo launcher (8) through cable plug (24); Data input cable is protected by cable retaining ring (23,28).

9. system according to claim 4 is characterized in that, described transmitting coil (14) is a ring bodies of being made by permeability magnetic material, is wound with coil on ring bodies.

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