RU2272132C2 - Method for information transmission from well to surface - Google Patents

Abstract

FIELD: drilling equipment, particularly means for transmitting measuring-signals from the well to the surface.

SUBSTANCE: method involves receiving and transmitting coded electric signals through closed loop defined by drilling string and drilling mud in hole annuity of the well. Antennas are installed on outer drilling string surface and are made as coils wound on toroidal cores and arranged at well bottom and head correspondingly.

EFFECT: increased efficiency.

3 dwg

Description

The invention relates to drilling equipment, and in particular to means for controlling downhole parameters during drilling and well logging.

A known method of transmitting information (see, for example, AS No. 939747, class E 21 B 47/12, publ. 06/30/82) from the bottom of the well along the column of flushing fluid by creating on the bottom of the hydraulic pressure pulses and their reception on surface. Downhole information is encoded by a sequence of pulses of a certain duration, which are converted on the bottom to pressure pulses and propagate along the column of flushing fluid - drilling mud to the surface.

The disadvantage of this method is the low speed of information transfer, since the attenuation of pressure pulses in the mud column depends on the pulse repetition rate, and only at low frequencies (of the order of a few tens of hertz) can an acceptable transmission range of such signals be provided.

A known method of transmitting an information signal from a well to the surface using a galvanic communication channel through a drill pipe string (see, for example, AS No. 150952, class E 21 V, publ. 1962).

The disadvantage of this method is that the electromagnetic signal is radiated into the surrounding rock bottom and before it reaches the surface, it is strongly scattered. Therefore, to implement this method, a powerful power plant is needed - a downhole electric power generator, which complicates the downhole equipment, increases the dimensions of the telemetry system and reduces its reliability. In addition, the presence of salt-containing formations between the surface and the face prevents the passage of an electromagnetic signal to the surface, i.e. the implementation of this method becomes impossible.

Closest to the claimed method is a method of drilling deviated and horizontal wells, which is based on the transmission and reception of coded electrical signals in a closed loop from a drill pipe string and drilling fluid by antennas in the form of a winding on a toroidal core, one of which is located in the bottomhole zone, the other one at the wellhead, and the conversion of coded electrical signals (see RF patent No. 2162521, class E 21 B 47/12, publ. 01.27.02).

The disadvantage of this method is the low efficiency of the radiation of the electric signal at the bottom due to the small size of the cylinder installed inside the drill pipe, which reduces the transmission distance and requires additional energy consumption in the downhole equipment.

In addition, it is technologically and structurally difficult to install the antenna on the inner surface of the pipe.

The aim of the present invention is to increase the radiation efficiency of an electric signal with a sufficiently low power consumption and simplify the design.

This goal is achieved by the fact that in the method of transmitting information from the well to the surface, based on the transmission and reception of encoded electrical signals in a closed loop from the drill pipe string and drilling fluid by antennas in the form of a winding on a toroidal core, one of which is located in the bottomhole zone, the other - at the wellhead, and the conversion of coded electrical signals, the toroidal cores of the antenna are installed on the outer surface of the drill pipe string, and a closed loop is formed drill pipe and the mud in the annulus.

The method of transmitting information from the well to the surface is illustrated by drawings, where Fig. 1 shows a simplified diagram of a device that implements a method of transmitting information from the well to the surface with antennas made in the form of toroidal cores, Fig. 2 shows oscillograms explaining the operation of this device.

An example implementation of the method

The radiating antenna 1 is made in the form of a toroidal core 2, which is "mounted" on the drill pipe 3 and is located near the bottom of the well (see figure 1). The winding 4 on the toroidal core 2 is connected to an amplifier 5, the output electrical signal from which, carrying downhole information, is to be transmitted to the surface of the well. Electronic blocks - amplifier 5, signal conditioner 6, analog-to-code converter 7 and measuring unit 8 are placed in a special sealed container located near the bottom of the well inside the drill pipe. The radiating antenna 1 is closed by a tight hermetic casing 9, which protects it from mechanical influences and from drilling mud. The container in which the electronic units of the radiating antenna are located is not shown in FIG. 1.

At the wellhead there is a receiving antenna 10, which is also made in the form of a toroidal core 11 with a winding 12 and is protected from mechanical influences and drilling mud by a casing 13. The ends of the winding 12 are brought to the surface and connected to the input of the amplifier - filter 14, which emits the signal received from the bottom of the antenna 10. The selected signal passes the shaper 15, which provides coordination of the signal parameters with the computer, where the signal from the bottom goes for processing and calculations.

A device that implements the method operates as follows.

, а в моменты времени, когда информационный бит равен "0", ток в обмотку 4 антенны 1 не передается. Осциллограмма сигнала на выходе усилителя 5 представлена на фиг.2б. Формирователь сигнала 6 обеспечивает заполнение импульсов несущей частотой, а усилитель 5 формирует необходимый уровень тока в обмотку 4 антенны 1. Протекающий в обмотке 4 переменный ток частотой f создает в тороидальном сердечнике 2 антенны 1 переменное магнитное поле той же частоты. Поэтому в любом электропроводном витке, охватывающем тороидальный сердечник, будет наводиться переменное напряжение той же частоты, а если этот виток будет замкнутым, то по нему будет протекать переменный ток частотой f. Такой замкнутый виток 16 образуется стальной бурильной трубой, стальным кожухом 9, электропроводящим столбом бурового раствора в скважине, стальным кожухом 13 на устье скважины. Этот замкнутый виток охватывает не только тороидальный сердечник 2 антенны 1, но точно также и тороидальный сердечник 11 антенны 10 на устье. Протекающий по этому витку переменный ток наведет в тороидальном сердечнике 11 антенны 10 переменное магнитное поле, которое наведет в обмотке 12 переменное напряжение частотой f. Осциллограмма этого напряжения представле на фиг.2в. Из-за затухания и рассеяния ток, проходящий по замкнутому витку 16 через тороидальный сердечник 11, будет в тысячи раз меньше, чем ток, проходящий по этому же витку через тороидальный сердечник 2 излучающей антенны 1 и сравним с уровнем электрических помех. Поэтому сигнал с обмотки 12 должен быть усилен и отфильтрован в усилителе-фильтре 14, после чего он поступает на формирователь 15, где после детектирования и сглаживания выделяется огибающая несущей частоты. Вид сигнала на выходе формирователя 15 представлен на фиг.2г. Принятая с забоя последовательность импульсов, представляющая собой закодированную информацию с измерительного блока 8, подается в компьютер для последующей обработки и вычислений.In the measuring unit 8 are sensors with which to measure the necessary downhole parameters, such as accelerometers and flux probes, to measure the well trajectory. The signals from the measuring unit 8 after the analog-to-code 7 converter are converted to binary code, i.e. at the output of the converter 7, a sequence of electrical pulses of a certain duration is formed. The presence of the pulse corresponds to bit "1", and its absence to the bit "0" (see figa). In the winding 4 of the antenna 1 at times when the information bit is "1", an alternating current of a fixed constant frequency is supplied

, and at times when the information bit is "0", current is not transmitted to the winding 4 of antenna 1. The waveform of the signal at the output of the amplifier 5 is presented in Fig.2B. The signal conditioner 6 provides filling of the pulses with the carrier frequency, and the amplifier 5 generates the required current level in the coil 4 of the antenna 1. The alternating current flowing in the coil 4 with a frequency f creates an alternating magnetic field of the same frequency in the toroidal core 2 of antenna 1. Therefore, in any electrically conductive coil covering the toroidal core, an alternating voltage of the same frequency will be induced, and if this coil is closed, an alternating current of frequency f will flow through it. Such a closed loop 16 is formed by a steel drill pipe, a steel casing 9, an electrically conductive column of drilling fluid in the well, a steel casing 13 at the wellhead. This closed loop covers not only the toroidal core 2 of the antenna 1, but also the toroidal core 11 of the antenna 10 at the mouth. The alternating current flowing through this coil will induce an alternating magnetic field in the toroidal core 11 of the antenna 10, which will induce an alternating voltage of frequency f in the winding 12. The waveform of this voltage is shown in Fig.2c. Due to attenuation and scattering, the current passing through the closed loop 16 through the toroidal core 11 will be thousands of times smaller than the current passing through the same coil through the toroidal core 2 of the radiating antenna 1 and is comparable to the level of electrical noise. Therefore, the signal from the winding 12 must be amplified and filtered in the amplifier-filter 14, after which it enters the former 15, where after detection and smoothing the envelope of the carrier frequency is extracted. The type of signal at the output of the driver 15 is shown in FIG. The sequence of pulses received from the bottom, which is encoded information from the measuring unit 8, is fed to a computer for subsequent processing and calculations.

The claimed method with two toroidal antennas, one of which 1 is located on the bottom and the other 10 on the wellhead, allows not only to transmit information from the bottom to the wellhead, but also to work in the other direction - to transmit information from the wellhead to the bottom. In this case, the antenna 10 will be radiating, and the antenna 1 receiving. This bi-directional system has advantages, because it allows you to control the operating mode of the bottomhole block by transmitting signals to the face. For example, during stand-alone (battery) power supply of the bottomhole block, it is not continuous to transmit information from the bottomhole, but by a signal from the surface it will allow a multiple increase in the system’s operating time without recharging the batteries. If there is no special need for bi-directional transmission of information, the receiving antenna at the wellhead can be simplified.

In contrast to the prototype, the placement of antennas on the outer surface of the drill pipe in addition to simplifying the technology and design increases the power of the antennas, since the size of the cylinder of the magnetically conductive material installed inside the drill pipe is smaller than the size of the cylinder installed on the outer surface of the drill pipe, and as you know, the antenna power is determined the size of the cylinder is proportional to its volume.

Increasing the antenna power allows you to increase the reception range, i.e. work in deeper wells compared to the prototype.

Moreover, the communication channel of information transfer is more reliable, because it is an electrically conductive coil formed by a string of drill pipes and drilling fluid in the annulus, where the speed of the drilling fluid is lower than inside the drill pipes, and accordingly, there is less disruption of the electrically insulating layer on the surface of the drill pipes.

Claims (1)

A method of transmitting information from a borehole to a surface, based on the transmission and reception of encoded electrical signals in a closed loop from a drill pipe string and drilling fluid by antennas in the form of a winding on a toroidal core, one of which is located in the bottomhole zone, and the other is located at the wellhead encoded electrical signals, characterized in that the toroidal cores of the antennas are mounted on the outer surface of the drill pipe string, and a closed loop is formed by the drill pipe string and drill solution in the annulus of the well.

Images