Communications – electrical: acoustic wave systems and devices – Wellbore telemetering – Through drill string or casing
Patent
1993-06-17
1994-02-22
Lobo, Ian J.
Communications, electrical: acoustic wave systems and devices
Wellbore telemetering
Through drill string or casing
367 83, 3408544, G01V 140
Patent
active
052893545
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for transmission of drilling data from a well, from the bottom to the surface and, more particularly, to such a method using two parallel transmission channels between the bottom and the surface.
During the drilling of a well, for example an oil well, it is desirable for the head driller to know the conditions existing at the bottom of the well (deflection factors, rotation speed of the bit, weight on the bit, torque on the bit, temperature, accelerations etc.) in order better to control the parameters of the drilling. It is preferable to know these conditions in real time, which requires means for transmitting the data from the bottom of the well to the surface.
Knowing the conditions of the bottom of the well permits more rapid drilling and reduction in the costs of drilling. In addition, the head driller will have the possibility of rapidly reacting to any change in conditions, for example change in the type of rock or wear of the bit.
Several means for transmitting data from the bottom to the surface have been proposed. Among these means are transmission by electrical conductor and by acoustic or electromagnetic waves. Data transmission by pressure waves in the drilling mud has also been proposed. In such a system, the pressure of the mud travelling along the string of pipe is modulated, for example, by the agency of a servovalve mounted in a subassembly disposed in the string of pipe adjacent to the bit.
The transmission speed of the signal in such a system is not very high, the pressure waves propagating only at approximately 1500 m/s. Taking into account the deterioration of the waves between the bottom and the surface, inherent limitations in the modulation of the pressure of the mud and the necessity of maintaining the quality of the data at the surface, the data rate remains low.
The object of the present invention is to overcome the drawbacks of transmission of data by pressure waves in the drilling mud by providing a method for transmission of data which is simple and of increased reliability.
In order to do this, the invention proposes a method for transmission of data on the drilling conditions of a well, from the bottom to the surface, comprising the following operations: into the well; by means of a sensor; and are encoded for the said measurement; into the well; simultaneous detection of the vibrations generated in the string of pipe by the said pulses in the drilling mud.
Other characteristics and advantages of the present invention will emerge more clearly from reading the description hereinbelow with reference to the attached drawings in which:
FIG. 1 is a diagrammatic sectional view of a drilling assembly; and
FIG. 2 shows diagrammatically a processing circuit.
In FIG. 1 is shown a drilling assembly comprising a mast 10 fitted, in a manner known per se, with a hook 12 to which is suspended a string of pipe shown generally by 14. The string of pipe 14 comprises a drill bit 16, drill collars 18 and drill pipes 20. In the example illustrated, the string of pipe 14 is rotated by a rotary turntable 22 or by a motorised head called a "power swivel". The pressurised drilling mud passes from a source (not shown) inside the pipes 20 by a hose 24. This mud is recycled back to storage tanks (not shown) via a conduit 26. A servovalve mounted in a subassembly 28 disposed adjacent to the bit 16 is intended to interrupt selectively the flow of the pressurised mud in order to create pressure waves in the mud. Measurement and control devices are disposed in the subassembly 28 enabling, in a known fashion, to generate pressure waves in the mud which are representative of the measurements taken at the bottom. These pressure waves are detected at the surface by a pressure sensor 32 which is mounted on the hose 24.
The pressure waves created in the mud also generate corresponding vibrations in the string of pipe 14. According to the invention, it has been found that the reading of the data could be improved by mounting a second sensor on the string of pipe.
As show
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Clayer Frederic
Henneuse Henry
Sancho Jean
Lobo Ian J.
Societe Nationale Elf Aquitaine (Production)
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