JP2796747B2 - Multistage boring hole pressure measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention arranges a packer section and a pressure detection section alternately, divides a borehole into a plurality of sections by a parker section, and reduces the pressure in each section. The present invention relates to an apparatus for measuring by a pressure detection unit. This device applies the fluctuating water pressure or gas pressure in the ground, and measures the flow of groundwater in the ground and the permeability of the ground from the pressure propagation situation to a remote observation point and the permeation amount of the pressure water and pressurized gas. It can be used in research fields.

[Prior Art] Various investigations require pressure measurement in a borehole. One of the most popular examples is to investigate changes in groundwater levels over time.In addition, in the field of reservoir engineering in petroleum engineering, pressure is applied to a part of an oil reservoir to estimate oil reserves. For example, when measuring pressure propagation. These are often single point measurements. As an example of the multi-point measurement, there is a test for determining the water permeability of the ground by applying a water pressure to the ground and measuring the propagation speed thereof. In this method, pressurized water is injected into the ground, and the response pressure is measured in the ground away from the pressurized position.

In the prior art, a sensor such as a strain gauge, a semiconductor, a piezoelectric element, or the like is used for pressure detection.

[Problems to be Solved by the Invention] The above-mentioned pressure sensor basically utilizes various phenomena caused by deformation of a solid due to applied pressure. Due to the use of deformation, the larger the measured rated pressure of the pressure sensor, the stronger the structure must be for the pressure.The amount of deformation for a given pressure decreases, and the electrical analog output also decreases. . Moreover, when the electrical analog output decreases, it becomes buried in various noises, making it difficult to extract a signal. In other words, as the rated pressure increases, the sensitivity of the sensor,
Resolution and the like will be reduced.

By the way, the present inventors injected pressurized water into the transmission section cut off by the double packer in the boring hole (transmission hole) excavated in the fractured rock before, and pressurized water capable of grasping the time-dependent change in the flow rate was obtained. A method was proposed in which the inside of a borehole (receiving hole) was divided into a plurality of receiving sections in the depth direction, the response pressure change to the pressurized water was measured in each receiving section, and the rock permeability was tested numerically. . In this test, pressure propagation is often measured in a borehole having a depth of several hundred meters. This measurement is nothing less than a measurement of the change in pressure over time, and the magnitude of the change is very weak in this type of investigation. The magnitude of the distance decreases in inverse proportion to the second to third power of the distance as the distance from the pressing position increases. Also, as the measurement depth increases due to the influence of groundwater existing in the natural state, the water pressure in the natural state at the sensor position increases. The water pressure is a pressure that biases the fluctuating pressure, and the fluctuating pressure is built up thereon. Therefore, in a general conventional pressure sensor, when the measurement depth is increased for the above-described reason, there is a great possibility that a weak pressure is overlooked. In the above investigation, it is necessary to increase the distance between the pressurized point and the measurement point to obtain knowledge about the geological structure in a wide range, and the conventional pressure measuring device cannot meet such a demand. Further, since it is impossible to measure the pressure at multiple points at the same time with the conventional apparatus, the injection of pressurized water in the transmission section must be performed many times, and the influence of the repeated injection on the permeability of the ground cannot be ignored.

An object of the present invention is to divide the depth direction of a boring hole into a number of stages at arbitrary intervals, and to reduce the number of times of pressurized water injection by simultaneously measuring the pressure change in each of the sections. Accordingly, it is an object of the present invention to provide a multi-stage boring hole pressure measuring device that can accurately measure a weak fluctuating pressure even when the hydrostatic pressure of groundwater is large and has a structure suitable for reducing the diameter.

Means for Solving the Problems In order to achieve the above object, the present invention provides a basic structure in which three or more packers and a pressure detector located between the packers are detachably arranged in a line. Having. Each packer section includes a center pipe and a flexible packer tube which is coaxially located so as to surround the center pipe and maintains airtightness. Each pressure detecting unit includes a housing that is liquid-tightly connected to the center pipe, a quartz oscillator type pressure sensor that is incorporated therein to detect an external pressure, and a lead wire with a connector for a power supply and a signal. Have. The lead wires are connected by a cable with a connector inserted into the sensor pipe, and are sequentially connected from the packer at one end to the packer at the other end by a gas tube for packer inflation.

[Operation] The distance between adjacent packers can be freely changed by changing the center pipe length of the packers. After alternately connecting a desired number of packers and pressure detectors at desired intervals, the entire apparatus is lowered to a predetermined depth in the hole by a wire or a rod. When gas is supplied from the ground using a gas tube, each packer section expands and a plurality of independent receiving sections are set. The pressure in the reception section is measured by a pressure sensor.

The pressure sensor is of a quartz oscillator type, and utilizes a phenomenon in which the frequency of a quartz piece cut in a certain crystal direction changes according to the magnitude of the pressure applied thereto. The driving power is supplied from the ground, and the change in the frequency due to the change in the ambient pressure is measured on the ground surface. The power supply line is common to each pressure sensor,
If only the signal lines are led to the ground surface in parallel, the number of leads passing through the inside of the apparatus main body can be reduced. By employing the crystal oscillator type, it is possible to accurately detect a subtle change in pressure as a digital amount even when a large bias pressure is applied.

[Embodiment] FIG. 1 is an overall configuration diagram showing an embodiment of the apparatus according to the present invention. The device of this embodiment has a structure in which five packers 10 and four pressure detectors 12 located therebetween are detachably and alternately arranged in a line.

Each packer section 10 has a center pipe 14 located at the center.
And a rubber-made packer tube 16 which is coaxially located so as to surround it and maintains airtightness. FIG. 2 shows details of the uppermost packer, and FIG. 3 shows details of the heads of the other packers. The uppermost stage and the other stages have basically the same structure. An upper end plug 18 is attached to the upper end of the center pipe 14 and a lower end plug 19 is hermetically attached near the lower portion, and is provided between the packer tube 16 and the upper end plug 18 and between the packer tube 16 and the lower end plug 19. The space between them is hermetically connected by annular connecting members 20 and 21, respectively. The upper end plug 18 has the same center hole as the center pipe 14, and a connecting portion 22 is connected to an upper end thereof. The lower end of the center pipe 14 passes through the lower end plug 19. The upper end plug 18 and the lower end plug 19 are formed with air passages 24 and 25 in the axial direction, respectively, so that the cylindrical space S surrounded by the packer tube 16 can communicate with the outside. Are provided with union joints 26 and 27 for air tubes, respectively.

Next, the pressure detection unit 12 includes a housing 30 that is liquid-tightly connected to the center pipe 14, a quartz oscillator type pressure sensor 32 incorporated therein to detect pressure outside the housing, and a power supply and a signal thereof. , And connectors 36 and 37 are attached to the lead wire 34. The details of the pressure detector 12 are shown in FIG. 4 and FIG.
The housing 30 has a cylindrical shape and is liquid-tightly connected to a mounting base 38 having a central hole. A connecting portion 40 for connecting the lower end of the center pipe of the packer portion is similarly attached to the upper end of the housing 30 in a liquid-tight manner. Connection
An upper connector 36 is attached to 40 and is connected to the pressure sensor 32 by a lead wire 34. The pressure sensor 32 is mounted on a mounting base 38 by an L-shaped support fitting 42. A lower connector 37 is attached to the mounting base 38, and is connected to the upper connector 36 by a lead wire 34. A pressure receiving hole 50 is opened on the outer surface of the mounting base 38, and a pressure transmission path 52 communicating with the pressure receiving hole 50 is formed in the axial direction.
It has a structure that can transmit external pressure to 32. A connecting center pipe 56 is fixed to a lower end of the mounting base 38 by a fastening screw nipple 60. In this manner, the packers 10 and the pressure detectors 12 are alternately arranged.

Returning to FIG. 1, the connector 3 of the adjacent pressure detector 12
The cables 6 and 37 are connected to each other by a cable 62 with a connector passing through the center pipe 14, and are sequentially connected from the uppermost packer to the lowermost packer by a packer inflation air tube 64. The cable 62 can be easily connected / disconnected by a connector, and the air tube 64 can be easily connected / disconnected by the union joints 26 and 27.

Such an entire apparatus is suspended by a rod or a wire and lowered into a boring hole. At that time, the cable 70 is connected to the water-resistant connector 66 at the upper end, and is supplied with gas from the ground by connecting the air tube 68 to the upper union joint 26 of the uppermost packer.

The procedure for installing this device in the borehole is as follows. First, an air tube 64 is attached to the first (lowest) packer section 10 and lowered into the hole.
To join. After lowering it to such an extent that the connecting part 40 at the upper end of the pressure detecting part comes out of the head slightly from the hole, it is temporarily fixed.
After passing a cable 62 with a connector compatible with the connector 36 of the connecting portion 40 of the pressure detecting portion 12 through the center pipe 14 of the second-stage packer portion 10 and coupling the connectors, the second-stage packer portion 10 is removed. The first-stage pressure detection unit 12 is connected to the connection unit 40. Then, the lower end plug of the second-stage packer section 10
The air tube 64 from the first stage is connected to the union joint 27 provided at 19. In the same manner, the apparatus is assembled by sequentially following the number of stages.

A water-resistant connector 66 is provided at the head of the uppermost packer unit 10, and a cable 70 having a length corresponding to the measured depth is connected to this connector. Similarly, an air tube 68 having a length corresponding to the measurement depth is connected to the union joint 26 of the upper end plug 18.
To join. The cable includes a power supply line for driving all the pressure sensors and a signal line which is thin on the ground surface for signals from all the pressure sensors. When this device is suspended by a wire and lowered, the wire is tied to the shackle 72. When lowering using a rod, connect the rod to the top of the top packer. At this time, since it is very difficult to lower the cable 70 while penetrating the inside of the rod to the ground surface, in the present embodiment, the cable is pulled out of the rod using the cut-out cable side-out mechanism 74, and the cable is pulled out to the rod. Take a way to get along.

The packer unit 10 and the pressure detection unit 12 have an internal pressure sensor
A connection structure is adopted so that the connector 32 and the connectors 36 and 37 do not get wet with water, and the lead wires and cables penetrating therethrough are not twisted or entangled.

By the way, the crystal resonator type pressure sensor requires a total of four lead wires for transmitting information on power and pressure for exciting the internal crystal resonator. Therefore, in order to operate the four pressure sensors as in this embodiment, a 16-core cable is usually required. On the other hand, it is important to make the bore diameter as small as possible in order to economically perform the test targeted by the present invention. However, when the number of installed pressure sensors increases, the diameter of the cable also increases, making it difficult to reduce the diameter of the device. For this reason, in the present invention, the power supply lines of all the pressure sensors are made common, and are operated with a 10-core cable. With this configuration, the number of lead wires between the first and second stages at the bottom is four, and the number of lead wires between the second and third stages is six and three.
Eight between the 4th stage and 10 from the 4th stage to the upper part to the ground surface. When the number of installed pressure sensors is n,
The maximum required number of lead wires is 2n + 2 instead of 4n. The greater the number of pressure sensors installed, the greater the effect of reducing the number of leads, realizing a smaller connector and housing, and consequently a smaller overall device diameter. be able to.

FIG. 6 shows an example of use of the present apparatus. This is a conceptual diagram of the measurement of the permeability test. A transmission hole 82 and a reception hole 84 are excavated in a fractured rock mass 80 to be analyzed. The fracture is indicated by reference numeral 81. Generally, a plurality of receiving holes 84 are formed at different positions. Transmission hole
A transmission section 86 blocked by double packers 85a and 85b is set in 82, and pressurized water is injected from a water injection device 88 on the ground. The pressure, flow rate, and ground pressure in the transmission section at that time are sent to the converter 94 in the form of electric signals, and the converted data is sent to the recording / analyzing device 96.

The pressure measuring device of the present invention is inserted into the receiving hole 84. Here, it is divided into eight reception sections by nine packers 89. There is a pressure sensor 90 in each receiving section, and a detection signal thereof is sent to an indicator 92. Each pressure sensor
The signal detected at 90 represents a temporal change of the received pressure, and the data and the pressure and flow rate data at the transmitting hole are recorded and analyzed by the recording and analyzing device 96. By utilizing the present invention, the response pressure can be accurately detected in a large number of arbitrary reception sections at the same time, so that the number of tests performed in the same analysis target area can be reduced, the test work time can be reduced, and the analysis target area can be reduced. The amount of water injection can be reduced, and the change in rock mass caused by the increase in the amount of water injection can be minimized.

[Effect of the Invention] Since the present invention has a structure in which the packer portion and the pressure detecting portion are alternately detachably connected as described above, the interval of the packer portion can be changed by changing the length of the center pipe, and the desired interval can be changed. Many pressure detection sections can be easily set. Further, since they are connected to a cable having a connector by a gas tube, it is easy to change the number of stages and the packer interval.

Further, in the present invention, since a quartz oscillator type pressure sensor is incorporated as a pressure detecting unit, even when a large hydrostatic pressure is applied in a deep boring hole, a minute pressure fluctuation can be accurately measured. Furthermore, in the present invention, the measurement section can be divided into a plurality of sections and the pressure in those sections can be measured simultaneously, so that the measurement operation can be performed extremely easily and quickly.

Since the power supply line to supply the crystal unit pressure sensor is shared, the number of necessary lead wires can be reduced,
The connector and the housing can be reduced in size, and the entire device can be reduced in diameter. For this reason, the diameter of the boring hole to be excavated can be made as small as possible, which is advantageous in terms of economy.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an embodiment of a pressure measuring device according to the present invention, FIG. 2 is an explanatory diagram showing details of a top-stage packer unit, and FIG. 3 is a head of each of the other packer units. FIG. 4 is an explanatory view showing the details of the pressure detecting section, FIG. 5 is a sectional view taken along the line VV, and FIG. 6 is a conceptual view of a water permeability test utilizing the present invention. 10 ... Packer part, 12 ... Pressure detector, 14 ... Center pipe, 16 ... Packer tube, 30 ... Housing,
32 Pressure sensor, 34 Lead wire, 36, 37 Connector, 62 Cable, 64 Air tube, 88 Water injection device, 90 Pressure sensor, 92 Indicator, 94 ... Converter, 96 ... Recording / analyzing device.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazumasa Ito 4-6-6 Kudankita, Chiyoda-ku, Tokyo Applied Geology Co., Ltd. (56) References JP-A-3-55310 (JP, A) JP-A Heisei 2-304112 (JP, A) JP-A-63-95379 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) E02D 1/00 G01L 9/00 E21B 33/12 G01L 19 / 00

Claims (1)

(57) [Claims] 1. A structure in which three or more packers and a pressure detector located between the packers are detachably arranged in a line, and each packer has a center pipe and a center pipe surrounding the center pipe. A flexible packer tube which is coaxially located and maintains airtightness, wherein each pressure detecting unit is liquid-tightly coupled to the center pipe, and a quartz oscillator mounted therein for detecting external pressure. A pressure sensor and a lead wire with a connector for its power supply and signal are provided.Connecting the lead wires with a cable with a connector inserted into a center pipe, and sequentially from the packer at one end to the packer at the other end. A multistage boring hole pressure measuring device connected by a gas tube for packer expansion.