In-well seismic sensor casing coupling using natural forces in wells

Abstract

A mandrel housing for permanently deploying a seismic sensor or sensor apparatus down a well is disclosed. The mandrel is formed integral with or attached to a pipe and is incorporatable into the production piping string. The outer diameter of the mandrel is designed to be slightly smaller than the inside diameter of the well casing which allows the mandrel to naturally come into contact with the well casing at points of deviation, non-linearity, or non-verticality in the casing. This mechanical coupling of the mandrel to the well casing, and hence the earth formation, improves the resolution and type of seismic signals to be detected by the sensor apparatus. The sensor apparatus fits into a groove on the mandrel and is preferably clamped or welded into place or placed within a tunnel formed in the mandrel. The mandrel further preferably contains channels on its side to allow materials within the annulus to flow around the mandrel even when the mandrel is in contact with the casing.

What is claimed is:  
     
         1 . An apparatus deployable down a well having a casing with an inner diameter, comprising: 
 a mandrel containing a first tube coupleable to a production tube, the mandrel having an outside diameter; and    at least one fiber-optic-based seismic sensor housed within the mandrel.    
     
     
         2 . The apparatus of  claim 1 , wherein the mandrel is round in cross section.  
     
     
         3 . The apparatus of  claim 1 , wherein the mandrel is polygonal in cross section.  
     
     
         4 . The apparatus of  claim 1 , wherein the mandrel contains a plurality of protrusions extending radially from the mandrel.  
     
     
         5 . The apparatus of  claim 1 , wherein the sensor is housed within a groove formed in an outside surface of the mandrel.  
     
     
         6 . The apparatus of  claim 5 , further comprising a means for holding the sensor within the groove.  
     
     
         7 . The apparatus of  claim 1 , wherein the sensor is housed within a tunnel formed within the mandrel.  
     
     
         8 . The apparatus of  claim 1 , wherein the mandrel contains a plurality of channels.  
     
     
         9 . The apparatus of  claim 1 , wherein the sensor comprises three seismic sensors oriented orthogonally with respect to each other.  
     
     
         10 . The apparatus of  claim 1 , wherein the first tube is not concentric within the mandrel.  
     
     
         11 . The apparatus of  claim 1 , wherein the outside diameter of the mandrel is slightly less than that of the inner diameter of the casing.  
     
     
         12 . The apparatus of  claim 1 , further comprising a production tube coupled to the first tube, and further comprising a displacement device coupled to the production tube.  
     
     
         13 . The apparatus of  claim 1 , further comprising at least one channel formed on an outside surface of the mandrel to allow the passage of materials between the mandrel and the casing.  
     
     
         14 . An apparatus deployable down a well having a casing with an inner diameter, comprising: 
 a mandrel containing a tube coupleable to a production tube, the mandrel having an outside diameter slightly less than that of the inner diameter of the casing such that the mandrel is capable of directly contacting the casing by natural forces; and    at least one sensor housed within the mandrel.    
     
     
         15 . The apparatus of  claim 14 , wherein the mandrel is round in cross section.  
     
     
         16 . The apparatus of  claim 14 , wherein the mandrel is polygonal in cross section.  
     
     
         17 . The apparatus of  claim 14 , wherein the mandrel contains a plurality of protrusions extending radially from the mandrel.  
     
     
         18 . The apparatus of  claim 14 , wherein the sensor is housed within a groove formed in an outside surface of the mandrel.  
     
     
         19 . The apparatus of  claim 18 , further comprising a means for holding the sensor within the groove.  
     
     
         20 . The apparatus of  claim 14 , wherein the sensor is housed within a tunnel formed within the mandrel.  
     
     
         21 . The apparatus of  claim 14 , wherein the at least one sensor comprises at least one seismic sensor.  
     
     
         22 . The apparatus of  claim 21 , wherein there are three seismic sensors oriented orthogonally with respect to each other.  
     
     
         23 . The apparatus of  claim 14 , wherein the first tube is not concentric within the mandrel.  
     
     
         24 . The apparatus of  claim 14 , further comprising at least one channel formed on an outside surface of the mandrel to allow the passage of materials between the mandrel and the casing.  
     
     
         25 . The apparatus of  claim 14 , further comprising a production tube coupled to the first tube, and further comprising a displacement device coupled to the production tube.  
     
     
         26 . The apparatus of  claim 14 , wherein the sensor comprises an optical sensor.  
     
     
         27 . An apparatus deployable down a well having a casing with an inner diameter, comprising: 
 a mandrel containing a first tube coupleable to a production tube, the mandrel having an outside diameter; and    at least one sensor housed within a groove in the mandrel, wherein the first tube is not concentric within the mandrel.    
     
     
         28 . The apparatus of  claim 27 , wherein the mandrel is round in cross section.  
     
     
         29 . The apparatus of  claim 27 , wherein the mandrel is polygonal in cross section.  
     
     
         30 . The apparatus of  claim 27 , wherein the mandrel contains a plurality of protrusions extending radially from the mandrel.  
     
     
         31 . The apparatus of  claim 27 , wherein the sensor is housed within a groove formed in an outside surface of the mandrel.  
     
     
         32 . The apparatus of  claim 31 , further comprising a means for holding the sensor within the groove.  
     
     
         33 . The apparatus of  claim 27 , wherein the sensor is housed within a tunnel formed within the mandrel.  
     
     
         34 . The apparatus of  claim 27 , wherein the at least one sensor comprises at least one seismic sensor.  
     
     
         35 . The apparatus of  claim 34 , wherein there are three seismic sensors oriented orthogonally with respect to each other.  
     
     
         36 . The apparatus of  claim 27 , further comprising at least one channel formed on an outside surface of the mandrel to allow the passage of materials between the mandrel and the casing.  
     
     
         37 . The apparatus of  claim 27 , wherein the outside diameter of the mandrel is slightly less than that of the inner diameter of the casing.  
     
     
         38 . The apparatus of  claim 27 , further comprising a production tube coupled to the first tube, and further comprising a displacement device coupled to the production tube.  
     
     
         39 . The apparatus of  claim 27 , wherein the sensor comprises an optical sensor.  
     
     
         40 . A system for taking measurements in a well, comprising: 
 a well comprising a casing having an inner diameter;    a production tube disposed in the well;    at least one mandrel coupled to the production tube, the mandrel having an outside diameter; and    at least one sensor apparatus housed within the mandrel,    wherein the mandrel is in contact with the casing.    
     
     
         41 . The system of  claim 40 , wherein the mandrel is round in cross section.  
     
     
         42 . The system of  claim 40 , wherein the mandrel is polygonal in cross section.  
     
     
         43 . The system of  claim 40 , wherein the mandrel contains a plurality of protrusions extending radially from the mandrel.  
     
     
         44 . The system of  claim 40 , wherein the sensor is housed within a groove formed in an outside surface of the mandrel.  
     
     
         45 . The system of  claim 44 , further comprising a means for holding the sensor within the groove.  
     
     
         46 . The system of  claim 40 , wherein the sensor is housed within a tunnel formed within the mandrel.  
     
     
         47 . The system of  claim 40 , wherein the at least one sensor comprises at least one seismic sensor.  
     
     
         48 . The system of  claim 47 , wherein there are three seismic sensors oriented orthogonally with respect to each other.  
     
     
         49 . The system of  claim 40 , further comprising at least one channel formed on an outside surface of the mandrel to allow the passage of materials between the mandrel and the casing.  
     
     
         50 . The system of  claim 40 , wherein the outside diameter of the mandrel is slightly less than that of the inner diameter of the casing.  
     
     
         51 . The system of  claim 40 , wherein the mandrel contains a first tube coupled to the production tube, and wherein the first tube is not concentric within the mandrel.  
     
     
         52 . The system of  claim 40 , further comprising a displacement device coupled to the production tube.  
     
     
         53 . The system of  claim 52 , wherein the displacement device has a radial protrusion away from an axis of the production tube which is larger than the difference between one-half of the inside diameter of the casing and one-half the outside diameter of the production tube.  
     
     
         54 . The system of  claim 52 , wherein the displacement device touches the casing to displace the production device from the axis of the casing.  
     
     
         55 . The system of  claim 40 , wherein the sensor comprises an optical sensor.  
     
     
         56 . The system of  claim 40 , wherein the well is deviated, non-linear, or non-vertical.  
     
     
         57 . The system of  claim 56 , wherein the mandrel is in contact with the casing at a point of deviation, non-linearity, or non-verticality in the well.  
     
     
         58 . A method for deploying an apparatus capable of taking seismic measurements, comprising: 
 deploying a production tube down a well containing a casing with an inner diameter, wherein the production tube comprises at least one mandrel with an outside diameter which houses at least one sensor; and    contacting the mandrel and the casing by natural forces.    
     
     
         59 . The method of  claim 58 , wherein the mandrel is round in cross section.  
     
     
         60 . The method of  claim 58 , wherein the mandrel is polygonal in cross section.  
     
     
         61 . The method of  claim 58 , wherein the mandrel contains a plurality of protrusions extending radially from the mandrel.  
     
     
         62 . The method of  claim 58 , wherein the sensor is housed within a groove formed in an outside surface of the mandrel.  
     
     
         63 . The method of  claim 62 , further comprising a means for holding the sensor within the groove.  
     
     
         64 . The method of  claim 58 , wherein the sensor is housed within a tunnel formed within the mandrel.  
     
     
         65 . The method of  claim 58 , wherein the at least one sensor comprises at least one seismic sensor.  
     
     
         66 . The method of  claim 65 , wherein there are three seismic sensors oriented orthogonally with respect to each other.  
     
     
         67 . The method of  claim 58 , wherein the mandrel further comprising at least one channel formed on an outside surface of the mandrel to allow the passage of materials between the mandrel and the casing.  
     
     
         68 . The method of  claim 58 , wherein the outside diameter of the mandrel is slightly less than that of the inner diameter of the casing.  
     
     
         69 . The method of  claim 58 , wherein the mandrel contains a first tube coupled to the production tube, and wherein the first tube is not concentric within the mandrel.  
     
     
         70 . The method of  claim 58 , wherein contacting the mandrel and the casing by natural forces comprises the use of a displacement device coupled to the production tube.  
     
     
         71 . The method of  claim 70 , wherein the displacement device has a radial protrusion away from an axis of the production tube which is larger than the difference between one-half of the inside diameter of the casing and one-half the outside diameter of the production tube.  
     
     
         72 . The method of  claim 70 , wherein the displacement device touches the casing to displace the production device from the axis of the casing.  
     
     
         73 . The method of  claim 58 , wherein the sensor comprises an optical sensor.  
     
     
         74 . The method of  claim 58 , wherein the well is deviated, non-linear, or non-vertical.  
     
     
         75 . The method of  claim 58 , wherein contacting the mandrel and the casing by natural forces comprises contact between the mandrel and the casing at a point of deviation in the well.