Method and apparatus for seismic exploration
This patent describes a method for down-hole seismic exploration employing vibration emanating from a point deep in a well, comprising: attaching a spear to the lower end of the elastic steel column, the upper end of the column extending to the top of the well and above; attaching upper end of the column to a reaction mass vertically above and isolated from earth, through vertically mounted compression spring means and, in parallel with, a vertically mounted servo-controlled hydraulic cylinder-piston assembly; sensing the displacement of the spear relative to the earth in which the wall is located and developing from a displacement signal; reciprocating the piston in the hydraulic cylinder under servo control to apply vertical vibration to the upper end of the column and to the spear, while developing an electrical, pressure-differential signal corresponding to the pressure across the cylinder-piston assembly; adjusting the vertical vibration through the servo control in accordance with the displacement signal and the pressure differential signal, to seek and find an appropriate resonant frequency for the column in the range of 5 Hz to 250 Hz; maintaining the frequency at resonance generating and transmitting a down-hole signal; detecting the signal at a location at a known distance from the spear; and determining the time differential between transmission and detection of the signal.
- Assignee:
- URS Corp., San Mateo, CA
- Patent Number(s):
- US 4674591
- OSTI ID:
- 6184540
- Resource Relation:
- Patent File Date: Filed date 28 Feb 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
03 NATURAL GAS
NATURAL GAS DEPOSITS
SEISMIC SURVEYS
PETROLEUM DEPOSITS
CONTROL SYSTEMS
CYLINDERS
ELECTRICAL EQUIPMENT
EXPLORATION
EXPLORATORY WELLS
FREQUENCY CONTROL
HYDRAULIC EQUIPMENT
HZ RANGE
MECHANICAL VIBRATIONS
PISTONS
PRESSURE MEASUREMENT
RESONANCE
SERVOMECHANISMS
SIGNALS
STEELS
ALLOYS
CONTROL
CONTROL EQUIPMENT
EQUIPMENT
FREQUENCY RANGE
GEOLOGIC DEPOSITS
GEOPHYSICAL SURVEYS
IRON ALLOYS
IRON BASE ALLOYS
MINERAL RESOURCES
RESOURCES
SURVEYS
WELLS
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration