JPH0750168B2 - Geological exploration method - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a geological exploration method for measuring the condition of a geological formation during the excavation of an oil well on the ground.

[Prior art]

Conventionally, at the time of excavating an oil well, etc., as a technique for transmitting information on the tip of a digging pipe, that is, the formation around the drilling bit to the ground by a drilling turret or a drilling rig, to the ground, A method of wireline logging is widely used, in which the detector is hung up at the tip of the wire after the drilling pipe etc. are all lifted up from the well, and the detector is hung at the bottom of the well to obtain stratum information on the ground. In this case, there is a drawback that reduction of excavation efficiency cannot be avoided due to lifting of the excavation pipe.

Therefore, in recent years, a continuous bottom hole data telementing system that uses mud pulses that continuously transmits information such as the bottom layer formation to the ground from the bottom hole that is being excavated is also known as measuring whirl drilling. Although it has been in the limelight in recent years, there is a problem that the cost of the device and the maintenance cost increase in this case as well.

[Object of the Invention]

The present invention has been made in order to overcome the above-mentioned conventional drawbacks, and an object of the present invention is to provide a geological exploration method capable of easily exploring the geology around the tip of a drill pipe without interrupting the excavation work. To provide.

[Structure of Invention]

The geological exploration method of the present invention to achieve the above objects,
While arranging a magnetic field generating coil around the excavation pipe being excavated from the excavation turret or excavation rig into the ground, generate a magnetic field line with the excavation pipe itself as a core by energizing the coil, It is characterized in that the change in intensity of the magnetic lines of force is measured by a magnetic sensor on the ground to search the geology around the tip of the drill pipe.

〔Example〕

A procedure of geological exploration using the geological exploration method of the present invention will be described below with reference to the drawings.

First, the drawing shows the situation during the excavation of an oil well. The excavation turret installed on the ground or the rotary table 2 of the excavation rig 1 rotates the excavation pipe 3 and the drilling bit 4 attached to the lower end of the excavation pipe 3 excavates the ground. A coil 5 for generating a magnetic field is arranged on the ground around the drill pipe 3 (on the drilling rig 1 in the present embodiment), although the coil 5 is dug inward.

Therefore, when a current having a constant or modulated frequency is applied to the coil 5 from the power source 6, the magnetic force line indicated by an arrow M in the drawing connects the drilling bit 4 at the lower end of the drill pipe 3 and the upper end of the drill pipe 3. Occurs around the drill pipe.

Next, as the physical properties of the soil around the drilling bit 4 change as the excavation progresses, the magnetic force lines M change, and the intensity change of the magnetic force lines is measured by the magnetic sensors 7 arranged on the ground G. By doing so, it is possible to continuously obtain information on changes in the formation during excavation.

That is, the information on the physical properties of the stratum due to the progress of excavation becomes the intensity change of the magnetic force line M, which can be continuously detected on the ground G.

In order to realize the detection of the physical properties of the stratum on the ground by the stratum exploration method of the present invention as described above, the above-mentioned ground G
It is necessary to know the correlation between the changes in the magnetic field and the physical properties of the soil, and to have such a database, and judge the soil properties in light of the changes in the magnetic field.

In other words, if the strength change of the magnetic field lines M with the change of the depth of the drill pipe 3 is measured on the ground and analyzed by the above database, the change of the physical properties of the stratum depending on the depth may be the strength change of the magnetic field on the ground. This is exactly equivalent to the method of knowing the condition of the stratum from the difference in seismic wave velocity depending on the stratum in the case of seismic exploration in which the stratum exploration is performed by artificial earthquakes.

〔The invention's effect〕

As described above, according to the present invention, a magnetic field generating coil is arranged around a drill pipe that is being dug toward the ground from a drilling turret or a drilling rig, and the coil is energized to core the drill pipe itself. Since the magnetic field lines are generated, and the intensity change of the magnetic field lines is measured by a magnetic sensor on the ground to search the geology around the drill pipe tip, the drill pipe tip is not interrupted without interrupting the drilling work. It became possible to easily explore the surrounding geology. Further, since a coil for generating a magnetic field, its oscillation circuit, a power source, etc. can be arranged on the ground to apply arbitrary power, there is an advantage that the device and operation are simple, and vibration and noise do not occur. Moreover, maintenance is easy,
There is an advantage that geological exploration at low cost can be obtained.

On the other hand, magnetic noise from other magnetic sources can be removed by giving arbitrary modulation to the magnetic field generated by the magnetic coil, and the surroundings will not be affected by magnetism.

The geological exploration method of the present invention can be effectively applied to a wide range such as drilling a geothermal well as well as drilling an oil well.

[Brief description of drawings]

The drawings are cross-sectional views of strata showing an example of a situation during excavation of an oil well using the stratum exploration method of the present invention. 1 ... Drilling rig, 3 ... Drilling pipe, 4 ... Drilling bit, 5 ... Coil, 7 ... Magnetic sensor, G ... Ground, M
…… Magnetic field lines.

Claims (1)

[Claims] 1. A magnetic field generating coil is disposed around a drill pipe during excavation from a drilling tank or a drilling rig into the ground, and
A geological exploration in which the coil is energized to generate a magnetic force line having the drill pipe itself as a core, and then the intensity change of the magnetic force line is measured by a magnetic sensor on the ground to search the geology around the tip of the drill pipe. Method.