1. Field of the Invention
The present invention relates generally to the field of well logging and, more particularly, to a logging tool that can be coupled to a borehole creating device for making a log of soil properties in a borehole.
2. Description of the Related Art
Soil probing tools are commonly used for subsurface investigations. These tools are typically driven into the ground using percussion hammers and are primarily used for sampling soil vapor, soil cores, and/or ground water. With the increasing usage of these probing tools, improvements have been made in the tools and the driving mechanisms such that the depth of investigation at which the probing tools are used has gradually increased. One use of such probing tools has been the exploration of a site for naturally occurring compounds or foreign contaminants in the soil and ground water of the site.
Systems have been developed for logging soil properties in a borehole as the probing tool is being driven into or retracted from the ground. For example, U.S. Pat. No. 5,639,956 issued to Christy, discloses a soil probe having a permeable membrane sensor disposed in the sidewall of the probe for sampling chemical compounds at different soil levels. Other types of sensors have also been placed on soil probes to measure and log properties of the soil at various levels as the probe is driven into or retracted from the soil.
However, sensors that are mounted on the probe rods are often exposed to damaging vibrations from the percussion hammers and other equipment used to drive or push the probe rods into the soil. Tools and sensors that are exposed to the vibrations of the driving equipment are subject to frequent breakage. Accordingly, only sensors that are able to withstand such damaging vibrations can be used to measure soil properties with these systems.
Systems have also been developed for logging soil properties in open boreholes in the water well, mining, and oil exploration industries. These tools have been used in both consolidated (rock) and unconsolidated (soil) formations. For example, U.S. Pat. No. 4,899,320 issued to Heam et al., U.S. Pat. No. 5,541,889 issued to Priest et al., U.S. Pat. No. 5,255,245 issued to Clot, and U.S. Pat. No. 6,986,650 issued to West, disclose devices for measuring soil properties in open boreholes. Some of these tools are also equipped with means to expand the tool so that it is held against the wall of the borehole.
However, these tools generally require a borehole to be formed by a probe rod or drilling tool in an earlier operation, and the probe rod/drilling tool to be removed from the borehole before the logging tool is deployed into the borehole. The logging tool is then lowered into the borehole and pulled to the surface using a cable attached to the logging tool. Also, the expansion devices associated with these tools move the tools into contact with the sidewall of the borehole, but are not designed to force a sensor laterally beyond the wall of the borehole into soil that has not come into contact with the driven probe rods.
There is a need in the industry for an improved soil logging system that alleviates the problems associated with the prior art logging systems described above.
A system and method are provided for logging soil properties in a borehole. The borehole can be created by a probe rod assembly having a string of hollow cylindrical casings, also referred to as rods, connected together end-to-end with an expendable point or a cutting shoe at the lower end. The rod assembly can be driven into the ground using percussion hammers or other conventional equipment.
A logging tool is deployed through an inner bore of the probe rod assembly after the probe rod assembly is driven or otherwise inserted into the soil to the bottom of the borehole. The probe rod assembly is then raised from the bottom of the borehole an amount sufficient to expose a sensor carrier of the logging tool at the lower end of the probe rod assembly. A sensor component is mounted on the sensor carrier for measuring one or more properties of the soil in the borehole. A packer is provided for forcing the sensor carrier laterally into a wall of the borehole immediately below the lower end of the probe rod assembly. The logging tool is coupled to the probe rod assembly by a locking structure, such as a plurality of spring locks that engage a corresponding groove in the inner bore of the probe rod assembly. By coupling the logging tool and probe rod assembly together, the sensor component can be used to measure soil properties as the rod assembly and logging tool are raised together in the borehole.
According to one aspect of the present invention, a method of logging soil properties is provided, comprising: inserting a borehole creating device into soil to a desired depth; deploying a logging tool through an inner bore of the borehole creating device after the device is inserted into the soil; and contacting soil below the lower end of the borehole creating device with the logging tool to measure at least one property of the soil.
According to another aspect of the present invention, a system for logging soil properties in a borehole is provided, comprising: a borehole creating device adapted to be inserted into soil to a desired depth to form a borehole; and a logging tool adapted to be deployed through an inner bore of the borehole creating device after the device is inserted into the soil, the logging tool comprising a sensor component for measuring at least one property of the soil below the lower end of the borehole creating device as the borehole creating device is lifted out of the borehole.
According to another aspect of the present invention, a tool assembly for logging soil properties in a borehole is provided, comprising: a logging sensor carrier; a packer for forcing the sensor carrier laterally into a borehole wall; and a locking structure adapted to engage a corresponding structure on a borehole creating device upon deploying the tool assembly through an inner bore of the borehole creating device until the logging sensor carrier protrudes from a lower end of the borehole creating device.
According to another aspect of the present invention, a sensor carrier for logging soil properties in a borehole is provided, comprising: means for attaching the sensor carrier to a borehole creating device; an outer face arranged to be forced laterally into soil beyond a vertical face of the borehole; and a first sensor component carried by the sensor carrier and exposed on the outer face.
Numerous other objects of the present invention will be apparent to those skilled in this art from the following description wherein there is shown and described an embodiment of the present invention, simply by way of illustration of one of the modes best suited to carry out the invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various obvious aspects without departing from the invention. Accordingly, the drawings and description should be regarded as illustrative in nature and not restrictive.
The present invention will become more clearly appreciated as the disclosure of the present invention is made with reference to the accompanying drawings. In the drawings:
A system and method for logging soil properties in a borehole according to the present invention will now be described in detail with reference to
A borehole creating device 10 in the illustrated embodiment is a hollow cylindrical casing 11 that can be driven into the ground by a string of hollow cylindrical probe rods 12 connected together end-to-end. The borehole creating device 10 will also be referred to herein as the probe rod assembly 10, and the cylindrical casing 11 at the lower end will be referred to herein as the lower probe rod 11. An expendable drive point 13 is positioned on the lower end of the lower probe rod 11 when the device 10 is being driven into the ground G by a hydraulic percussion hammer or other conventional equipment. The borehole creating device 10 can be driven into the ground G in a conventional manner until a desired sampling depth is reached. In an alternative embodiment, the borehole creating device 10 can have a cutting shoe at the leading end, instead of an expendable drive point, so that soil core samples can be cut and collected from the inner bore in a known manner.
In a typical operation, a set of empty probe rods 11, 12 covered at their lower end with an expendable point 13 are first driven to the maximum depth of the proposed logging activity. Many different sizes of probe rods could be used for this purpose. For example, probe rods having an OD of 2.25 inches and an ID of 1.5 inches that are connected together end-to-end using threaded couplings can be used to form the probe rod assembly 10. Typically, at the time of driving, the probe rods 11, 12 are empty and contain only air. The probe rods 11, 12 may then be filled with water so that the hydrostatic pressure inside the rods 11, 12 is equal to or greater than the surrounding formation.
The borehole creating device 10 is used together with a logging tool 14 to measure and create a log of soil properties. These properties can include, for example, mechanical, electrical, chemical, or other physical properties of the soil. These properties can also include properties of the groundwater or other materials found in boreholes, such as consolidated rock formations, minerals, contaminants, and the like. As used herein, the phrase “property of the soil” will be understood to include properties of soil and other materials found in boreholes.
The logging tool 14 of the present invention is a “post-run” device, which means that the logging tool 14 is not carried by the borehole creating device 10 into the borehole B as the device is being driven into the ground G. Instead, the logging tool 14 is deployed by inserting it through an inner bore 15 of the probe rods 11, 12 after the borehole creating device 10 reaches its final sampling depth. This eliminates the need to design or select sensors that can withstand the damaging vibrations from percussion hammers and other equipment typically used to drive or push the probe rods 11, 12 into the soil G.
A push rod assembly 16 is provided for pushing the logging tool 14 through the inner bore 15 of the probe rods 11, 12. The push rod assembly 16 can be a set of rods connected end-to-end, such as 0.5 inch diameter PVC pipe sections, which have a sufficient rigidity to push the logging tool 14 down the inner bore 15 of the probe rod assembly 10.
The logging tool 14 includes a logging sensor carrier 17 and one or more sensor components on the logging sensor carrier 17 for measuring at least one property of the soil. As used herein, the phrase “sensor component” includes sensors that measure properties of the soil, as well as sampling devices and sensor interfaces that collect samples for analysis at another location. In the illustrated embodiment, the sensor components include an electrical conductivity sensing array 18a, a membrane sampling interface 18b, and a hydraulic profiling port 18c. The sensor components 18a-18c can include any of a variety of sensor technologies for performing logging operations, including but not limited to: membrane sampling interface, electrical conductivity, gamma ray, video camera, accelerometers or geophones for geophysical measurements such as shear wave measurements, hydraulic profiling via water injection, fluorescence detectors, thermo conductivity, ground water sampling, and so forth. The sensor components 18a-18c can be connected to a computer or other data collection device at the soil surface by electrical wires, hoses, fiber optic cables or other communication means contained in a trunkline 19 that extends down through the probe rod assembly 10.
The membrane sampling interface 18b in the illustrated embodiment is a membrane used to transfer contaminants from the soil to a fluid medium on the probe side of the membrane. The membrane sampling interface 18b can be, for example, the membrane system used on the membrane interface probe described in the Applicant's prior U.S. Pat. No. 5,639,956.
A packer 20 is provided for forcing the sensor carrier 17 laterally into the sidewall W of the borehole B. The packer 20 includes a resilient packer protection blade 21 and a bladder 22 located between the packer protection blade 21 and the logging sensor carrier 17. The packer protection blade 21 is attached to a body 23 of the logging tool 14 and extends downwardly therefrom. The bladder 22 is expandable upon application of fluid pressure to force the sensor carrier 17 laterally into the sidewall W of the borehole B. The fluid pressure is supplied to the bladder 22 through a hose contained in the trunkline 19 that connects to a pressure source at the ground surface.
Other types of packers can also be used to accomplish the objectives of the present invention. For example, a linear actuator powered by a pneumatic or hydraulic pressure source can be used to apply lateral forces to the sensor carrier, or a mechanical linkage can be used to apply the lateral forces.
The logging sensor carrier 17 is connected to the body 23 of the logging tool 14 by a resilient arm 24 that biases the sensor carrier 17 laterally toward the inner wall 25 of the probe assembly 10 (when positioned within the probe assembly) and toward the sidewall W of the borehole B (when deployed outside the lower end of the probe assembly 10). A pair of threaded bolts, screws, pins, rivets, or other suitable fasteners 24f can be used to connect the sensor carrier 17 to the resilient arm 24. The sensor carrier 17 can be formed in a variety of shapes and configurations to suit a particular application. In one embodiment, the logging sensor carrier 17 is a blade that can be forced laterally into soil beyond a vertical face of the borehole sidewall W. This allows the sensor component(s) 18a-18c to be pushed into soil G that has not come into contact with the borehole creating device 10.
A locking structure 26 is provided for coupling the logging tool 14 to the borehole creating device 10 upon deployment of the logging tool 14. The locking structure 26 in the illustrated embodiment includes a plurality of spring locks 27 that protrude from an outer surface of the body 23 of the logging tool 14. A groove 28 is formed in the inner bore 15 of the lower probe rod 11 in a location corresponding to the spring locks 27 of the logging tool 14.
In use, the logging tool 14 is deployed through the inner bore 15 of the probe rods 11, 12 until the logging sensor carrier 17 protrudes from a lower end of the borehole creating device 10. The spring locks 27 of the logging tool 14 then engage the corresponding groove 28 in the lower probe rod 11 to couple the logging tool 14 and the borehole creating device 10 together so that the logging sensor carrier 17 protrudes from the lower end of the lower probe rod 11.
In another embodiment the locking structure is formed by making an inner wall of the borehole creating device 10 with a reduced diameter section. The reduced diameter section engages an enlarged outer diameter section on the logging tool 14 when the sensor component(s) 18a-18c of the logging tool 14 protrude from the lower end of the borehole creating device 10.
The locking structure 26 allows the logging tool 14 to be used to measure and log soil properties as the probe assembly 10 and the logging tool 14 are lifted together out of the borehole B. The lifting forces are transmitted by the probe assembly 10 to the logging tool 14 through the locking structure 26.
The logging tool 14 can also be equipped with a structure for sampling groundwater. As shown in
In
In
Additional details of the logging sensor carrier 17 are shown in
The upper end 40 of the sensor carrier 17 tapers to a point 46 and provides the leading edge for engaging the soil G in the borehole B as the assembly 10 is raised during logging operations. A pair of attachment openings 47 are provided near the upper end 40 for receiving threaded fasteners that connect the sensor carrier 17 to the arm 24. The attachment openings 47 and arm 24 are arranged to allow the outer face 42 of the sensor carrier 17 to move beyond an outer wall of the borehole creating device 10 upon deployment through the lower end of the lower probe rod 11.
A first sensor bore 48 is located near the upper end of the sensor carrier 17 to mount a first one of the sensor components, such as the electrical conductivity sensor array 18a. A second sensor bore 49 is located near the middle of the sensor carrier 17 to mount a second one of the sensor components, such as the membrane sampling interface 18b. A third sensor bore 50 is located near the lower end of the sensor carrier 17 to mount a third one of the sensor components, such as the hydraulic profiling port 18c.
A series of grooves 51 are cut into the inner face 43 of the carrier 17 to accommodate electrical wiring, gas lines, fluid lines, and the like for communicating with the sensor components 18a-18c. In the illustrated embodiment, the grooves 51 include a first groove 52 that extends along an upper section of the sensor carrier 17 from a point near the attachment openings 47 through the first sensor bore 48 to a first groove junction 53. The first groove 52 branches into second and third grooves 54, 55 at the first groove junction 53, which extend along a middle section of the sensor carrier 17 on both sides of the second sensor bore 49 to a second groove junction 56. The second and third grooves 54, 55 merge into a fourth groove 57 at the second groove junction 56, which extends along a lower section of the sensor carrier 17 to the third sensor bore 50.
Fifth and sixth grooves 58, 59 extend from the first and second groove junctions 53, 56, respectively, to respective end points immediately above and below the second sensor bore 49. The fifth and sixth grooves 58, 59 can be used to position a heater element 60 above and below the membrane sampling interface 18b located in the second sensor bore 49. The heater 60 is used to heat the area surrounding the membrane for the membrane sampling interface 18b, which causes particles near the membrane to more readily diffuse across the membrane and give better detection and lower carry-over on the membrane. A thermocouple 61 is also positioned in the grooves 58, 59 for monitoring and maintaining the temperature of the sensor carrier 17, e.g., by a thermometer and thermostat located above ground.
A bundle 62 of electrical wiring, gas lines, fluid lines, and the like extends from the trunkline 19 into the upper end of the first groove 52 and passes among the sensor components 18a-18c, the heater 60, and the thermocouple 61. In the illustrated embodiment, the bundle 62 includes a heater wire for powering the heater, a sensor wire for communicating with the thermocouple 61, a first gas line to carry gas to the membrane sampling interface 18b from a carrier gas supply located above ground, a second gas line to carry gas from the membrane sampling interface 18b to a detector located above ground, electrical wires to supply power and carry signals from the electrical conductivity sensing array 18a, and fluid lines to carry water or other suitable fluids to the hydraulic profiling port 18c for injection and pressure monitoring. Various other electrical wires, fluid lines, gas lines, fiber optic cables, and the like can be located in the grooves 51 of the sensor carrier 17 to accommodate the particular sensors used. When the sensor components 18a-18c are installed and the wires and lines are all connected, the inner side 43 of the sensor carrier 17 can be covered with a resin or other suitable backing material to protect and maintain the elements together within the grooves 51.
The system for logging soil properties in a borehole according to the present invention is described above. A method of logging soil properties according to the present invention will now be described.
The borehole creating device 10 is inserted into soil G to a desired depth without the logging tool 14, as shown in
The borehole creating device 10 is then pulled back from the expendable point 13 while maintaining downpressure on the push rod assembly 16 to keep the logging tool 14 at its lowered position, as shown in
The packer 20 is then deployed, as shown in
Also, once the logging tool 14 is forced out of the lower end 35 of the probe rod assembly 10, then the push rod assembly 16 can be retracted from the bore 15 of the probe rods 11, 12. Removal of the push rod assembly 16 helps keep the push rods out of the way during the subsequent soil logging operation.
The borehole creating device 10 and the logging tool 14 are then lifted simultaneously due to the interlocking structure of the spring locks 27 and the inner groove 28, as shown in
As the logging tool 14 is pulled upward in the borehole B, a retraction force can be measured with a tensile force gauge 32 as shown in
While the invention has been specifically described in connection with specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.
This application claims priority of U.S. Provisional Application No. 60/983,913 filed on Oct. 30, 2008. The content of this prior application is incorporated herein by reference.
Number | Date | Country | |
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60983913 | Oct 2007 | US |