Production logging mechanism for across-the-borehole measurement

A production logging tool for use in deviated wellbores is provided having an elongate tool body and an elongate sensor probe that is capable of lateral movement relative to the tool body. The sensor probe is connected to the tool body by a mechanism serving to deploy the sensor probe such that it is oriented across the wellbore. The tool body has a defined weight and the probe has a weight less than the defined weight, thus causing gravity induced orientation of the sensor probe so as to extend from top to bottom of the fluid passage for sensing all phases of the fluid present therein. The sensor probe is typically of elongate configuration and may support a single elongate sensor or a plurality of independent similar or dissimilar sensors arranged in spaced relation along the length of the probe. Orientation of the sensor probe across the borehole is accomplished mechanically by coil or leaf springs or by a hydraulically or pneumatically powered mechanism or by an electric motor driven mechanism.

FIELD OF THE INVENTION 
This invention relates generally to measurement of discrete and average 
fluid properties of flowing production fluid from wells and more 
particularly to well production logging instruments having means for 
measurement across the borehole especially to accommodate the propensity 
of complex well fluids to become segregated and flow in stratified manner 
in deviated wells. This invention also relates to mechanisms for 
positioning the sensors of a production fluid logging tool or logging tool 
of other character in decentralized close proximity to the wall surface of 
a well bore or well casing to facilitate efficiency of well logging and to 
permit efficient running of the tool. 
BACKGROUND OF THE INVENTION 
As used herein the terms "wellbore", "borehole" and "fluid passage" are 
intended to encompass any flow passage such as is defined by a drilled 
bore in an earth formation, a well casing or production conduit that is 
present within the drilled bore or any other pipe or tubing that defines a 
flow passage through which fluid, such as well fluid may flow. The term 
"fluid" as used herein encompasses liquids such as crude oil and water and 
gases such as natural gas, as well as mixtures of crude oil, water and 
natural gas. 
Due to the plurality of fluids in a producing oil well, flow regimes for 
the production of petroleum fluids from wells can become extremely complex 
and segregated. This becomes even more acute in deviated wells for the 
reason that fluid phases, fluid density and the action of gravity on the 
well fluid can significantly influence separation of the various phases of 
the production fluid when the well bore or flow conduit is deviated from 
the vertical. The lighter density production fluid will rise to the top of 
the deviated wellbore and pass over the heavier density fluid. Thus, it 
can be quite difficult to determine the average fluid properties (phase 
segregation) if conventional, centralized production logging instruments 
are employed. In wells producing more than one phase, the phases tend to 
move up the well at different velocities due to the difference in 
densities between the phases and in some cases one or more of the phases 
will be moving downwardly while other phases are moving upwardly. It has 
been firmly established that the light-density phases of the production 
fluid move up the well faster than do the heavy-density phases. It has 
been established that the lighter phases also occupy a small 
cross-sectional area when this phase segregation occurs as a result of 
wellbore deviation angles. 
Through-tubing logging instruments are limited in diameter to the size of 
the smallest restriction. These small instruments are traditionally run 
through the wellbore in such manner that the instrument and the sensors of 
the instrument are centralized within the wellbore, that is they are held 
by various means in the center of the pipe. With the instrument thus 
centralized, the measurement is made inside the tool body by sensors 
located within the instrument housing. Hence, if a centralized instrument 
is operated in a inclined borehole with multiple phases present, the 
instrument might not detect the light phase on the top of the borehole, or 
the heavy phase on the bottom. The phase detection that is accomplished 
through the use of conventional instruments can be quite inaccurate when 
deviated wells are logged. The purpose of this invention to measure the 
fluid parameters at many selected points across the borehole, rather than 
taking production fluid measurements in the center of the wellbore as is 
conventionally done. Conventional production logging instruments are 
normally operated in centralized manner within the borehole or well 
casing. When segregation in deviated wells occurs the centralized 
instruments do not read the average fluid composition. Rather, they tend 
to sense a fluid mixture that has an indicated heavier density and is thus 
inaccurate due to the fact that the lighter phase fluid migrates to and 
remains on the upper wall of the deviated wellbore. This holds true for 
fluid capacitance type instruments designed to determine the fraction of 
water in the production fluid mixture that is being produced from a well 
or present within the wellbore. 
Another problem with centralized logging techniques utilizing tools with 
embedded or internal sensors involves the quality of instrument 
centralization. If the instrument centralizers used in highly deviated 
wells do not provide sufficient force to properly overcome the weight of 
the instrument housing and its contents and to centralize the instrument, 
the instrument will tend to be decentralized by its own weight and will 
rest on or near the bottom wall surface of the wellbore. This leads to the 
sensor of the instrument being positioned in the heavy phase side of the 
deviated wellbore and the measurements taken to be erroneous with the 
heavy phase being dominant. 
The problem lies in the fact that a conventional production logging tool 
typically measures a local internal fluid sample in deviated wells and 
does not measure the fluid across the whole cross-section of the wellbore. 
Light phases that migrate to the top wall of the well are not measured by 
the internal sensors of the conventional centralized instrument. The 
advantage of the across-the-borehole type production logging devices 
according to the present invention is that these instruments, using 
sensors that are placed in a manner to measure from one side of the 
borehole to the other, can accomplish a true measurement that is 
representative of the actual production fluid mixture. This measurement or 
measurements includes all of the phases that are present in the fluid 
mixture. It is desirable, therefore that a production logging instrument 
be provided having sensors which measure a combination of the light phases 
that are present at the top wall of the deviated wellbore and the heavier 
phase or phases that are located at or near the bottom wall of the 
wellbore. These measurements are then true representations of the various 
phases that might be present in the production fluid; the measurements can 
be efficiently processed to accurately depict the character of the well 
fluid flowing or present within the wellbore. Additionally, because the 
instrument of this invention is run decentralized, the heavier body of the 
tool will be positioned by the influence of gravity in contact with the 
bottom wall of the wellbore thus, as a consequence, positioning the 
lighter weight sensor arm of the tool in contact with the top wall of the 
wellbore. As wellbore deviation is encountered by the tool, the influence 
of gravity will cause it to be automatically oriented with the tool body 
in engagement with the lowermost wall of the wellbore or casing and with 
the sensor arm in engagement with the uppermost wall. This tool therefore 
obviates the need for rigid centralization of the tool within the wellbore 
according to conventional practices and thus overcome the disadvantages 
associated with conventional centralized production logging instruments. 
PRIOR ART 
Earlier methods that have been employed as attempted solutions to the 
problems described above are classified into two general areas: The first 
attempted solution is the provision of a packer or diverter type 
production logging instrument. This instrument consists of a packer 
mechanism or a set of metal petals that is designed to force or divert the 
total flow of fluid through the body of the instrument to permit the 
instrument to take accurate readings. These methods overcome the fluid 
phase segregation problem by forcing all or most the light and heavy 
phases into the instrument for measurement. This is usually done with the 
logging instrument stationary within the wellbore by first lowering the 
instrument to the desired depth within the wellbore or well casing and 
then locking it in place and inflating the packer or opening the diverter. 
When this takes place a large pressure drop is created across the 
restriction of the smaller instrument flow passage which is incurred by 
forcing the larger borehole flow though the smaller sensing section of the 
instrument. This restriction, in combination with the restrictions of the 
location locking mechanisms of the instrument, can significantly retard 
the flow of production fluid and thus typically limits the use of these 
instruments to wells having low total flow rates, usually under 2,000 
barrels per day. Additionally, the pressure drop caused by restricted flow 
with the diverter active may not be the same as when the instrument is 
removed, thus potentially leading to the gathering of erroneous data about 
the production capability of the well. 
Another solution to the above problems has been a method using a 
combination of centralizers that, upon command, can open or close. These 
centralizers are then used in the closed condition in deviated wells to 
allow the instruments to contact or run on the bottom wall of the deviated 
wellbore. The measurements that are taken with this type of logging 
instrument in engagement with the bottom wall of the wellbore will be 
representative of the fluid phase or phases flowing along the bottom wall 
or in the lower portion of the flow passage, usually the heavier phase. 
The instrument is then centralized within the wellbore by opening the 
centralizers and a conventional reading is acquired. In this conventional 
position within the wellbore the fluid phase or phases that are present in 
the central portion of the flow passage will be sensed. Finally, one or a 
combination of these centralizers are closed or opened in an attempt to 
kick or shift the instrument to an angulated position within the wellbore 
to sense the fluid phase or phases that are present along the top wall of 
the deviated borehole. Obviously it is difficult to determine if the 
instrument has achieved the proper angulated position for sensing the 
fluid regime in the upper portion of the flow passage. Even if instrument 
positioning as described above is achieved, this method of production 
logging does not accomplish simultaneous and continuous sensing of all 
three areas of interest. These well production logs are run sequentially 
and therefore the data acquired are of different time frames and are 
sometimes difficult to correlate with each other in order to compute an 
average fluid composition. 
SUMMARY OF THE INVENTION 
It is a feature of this invention to provide a novel mechanism for 
accomplishing accurate measurement of average fluid properties of 
segregated or stratified flowing well fluid phases especially in highly 
deviated wells. 
It is another feature of this invention to provide a novel mechanism for 
well production logging wherein measurement of average fluid properties 
are taken simultaneously across-the-wellbore such that all phases of the 
flowing production fluid are efficiently measured for accurate 
determination of average fluid properties. 
It is an even further feature of this invention to provide a novel 
mechanism for well production logging having the capability of deploying 
multiple differing sensors across the borehole, such as for sensing 
temperature, capacitance and other fluid conditions and to process the 
sensor signals individually or combine the individual measurements to form 
the appropriate averages. 
It is another feature of this invention to provide a novel mechanism for 
well fluid production logging which, when introduced within the wellbore, 
automatically establishes logging tool decentralized positioning of an 
elongate fluid density sensor across a deviated wellbore and generally 
oriented from top to bottom to provide the capability for simultaneous 
detection of the heavy phase of the production fluid along the bottom wall 
of the wellbore and the light phase of the fluid that is present along the 
top wall of the wellbore. 
Briefly, the various features and advantages of the present invention are 
evident in the provision of an elongate logging tool body having a casing 
collar locator and having various sensors such as a pressure sensor, gamma 
ray sensor, density sensor and a telemetry section. The production logging 
tool body, because of its weight, will be positioned by the influence of 
gravity to engage or ride on the bottom wall of a deviated wellbore. The 
logging tool further incorporates an actuator strut mechanism that is 
movable relative to the tool body and is positioned by a suitable actuator 
mechanism so that a sensor such as a capacitance probe of the tool or 
other suitable density measuring device is positioned in inclined relation 
within the wellbore and extends across the wellbore. A set of springs or 
other suitable urging means will typically function as the power source of 
the actuator strut mechanism and provides sufficient force to hold an 
engagement section or sensor pad of the tool against the wall of the 
wellbore opposite the wellbore wall engaged by the body of the tool. 
Typically the actuator strut mechanism will engage the top wall of the 
wellbore as the result of gravity influences tool orientation. 
Alternatively, the strut actuator may be spring urged to its closed or 
retracted position and power operated its open or expanded position so 
that, in the absence of operating power, it can be automatically retracted 
to its closed position by the strut spring mechanism. From the standpoint 
of tool orientation the combination of gravity acting on the heavier tool 
body and the force of the springs or other urging means will be sufficient 
to ensure that the sensor pad automatically seeks a position so that it 
engages the top wall of the deviated wellbore. The capability of the tool 
to automatically orient an elongate sensor diametrically across the 
wellbore and to extend from the top wall to the bottom wall provides for 
the production of better quality information as to the wellbore fluid 
quantity and composition. There is no more pressure drop across the 
production logging tool than that of a conventional centralized type tool. 
When the logging tool is being employed well production parameters are not 
substantially altered. The logging tool mechanism can be run in the 
continuous mode; that is it can be lowered into and retrieved from the 
well while taking readings. It is not necessary for the tool to be 
stationary while logging measurements are being taken. 
The fluid flow logging tool of the present invention is naturally in a 
de-centralized mode in order to take its readings. This eliminates the use 
of conventional tool centralizers and thereby minimizes the length of the 
complete tool package that is to be placed in the well. Also, the 
capability for use of the logging tool in its de-centralized mode 
minimizes the potential for gathering erroneous data that might otherwise 
result if the tool were not centralized. In the case of conventional 
logging instruments insufficient centralizing force, thus enabling the 
influence of gravity to cause the sensor packages to ride nearer to the 
bottom wall of the deviated well bore typically causes the instrument to 
sense only the heavier phases of the fluid regime. The present invention 
overcomes this problem.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring now to the drawings and first to FIG. 1, a production logging 
tool constructed in accordance with the present invention and representing 
the preferred embodiment is shown generally at 10 and incorporates an 
elongate generally cylindrical tool body shown generally at 12 having a 
casing collar locator, a telemetry and gamma ray section 14 and an 
electronics package section 16. The tool body also includes a pressure 
sensor 18 and a density source 20. 
A section of the elongate tool body 12 is cut-away as shown at 22 to 
provide a laterally opening receptacle for receiving a sensor positioning 
mechanism shown generally at 24 when the logging sensor is fully collapsed 
so as to define a small cross-sectional dimension for traversing the 
borehole of a well or conduit to a desired depth and for retrieving the 
logging tool from the wellbore. The sensor positioning mechanism 24 
incorporates any one of a number of suitable actuator means for 
controllably expanding it to the position shown in FIG. 1 to accomplish 
de-centralization of the tool body 12 within the passage and to urge the 
logging sensor mechanism into engagement with the opposite wall of the 
passage. At its upper end the sensor positioning mechanism 24 includes an 
elongate sensor positioning member 26 which is connected by pivot 28 to 
the tool body at the upper end of the relieved or cut-away tool body 
section 22. The sensor positioning member 26 is adapted to pivot to a 
position of substantially parallel relation with the tool body section 23 
when disposed at its fully collapsed position. As shown in FIG. 1 the 
sensor positioning member 26 is extended from the sensor receptacle 22 to 
an angulated relation with the tool body section 23. The sensor 
positioning member may also provide support for other fluid condition 
detectors such as a temperature probe 30 for detecting the temperature of 
the flowing fluid medium at a central location within the flow passage or 
at a multitude of positions. An elongate wall contact member 32 is 
connected in pivotal relation with the lower end of the sensor positioning 
member 26 and is typically intended for orientation in substantially 
parallel relation with the wall surface of the wellbore or other conduit 
within which the logging tool is located. This wall contact member 32 may 
also provide for support of particular well logging instruments such as a 
density detector 34 which is shown to be connected at the upper end of the 
member 32. The wall contacting member 32 is also provided with upper and 
lower guide rollers 36 and 38 which establish rolling contact with the 
wall surface of the fluid passage and therefore serve to maintain the wall 
contact member 32 in parallel juxtaposition with the fluid passage wall 
surface diametrically opposite the line of contact of the tool body 12 
with the wall surface of the fluid passage. A lower elongate probe 
positioning element 40 is pivotally connected at its lower end 42 to a 
spring urged drive member 44 that is disposed in movable relation with the 
lower end of the tool body section 23. The drive member 44 is urged in an 
upward direction by a spring 46 in the form of a coil type compression 
spring. The spring 46 is preloaded when the sensor positioning mechanism 
24 is collapsed to its full extent so that when the sensor positioning 
mechanism 24 is released from its nested relation with the tool section 23 
the spring 46 will urge the lower end of the probe positioning member 40 
upwardly thus causing movement of the probe positioning member to an 
angulated relation with the tool body section 23 as shown in FIG. 1, while 
at the same time driving the wall contact member 32 outwardly into contact 
with the wall surface of the fluid passage. As an alternative, to provide 
for efficient tool retrieval in the absence of operating power, the spring 
46 can be arranged to move the drive member 44 to its closed or retracted 
position. In this case a drive motor such as a hydraulic or pneumatic 
actuator can be employed to move the sensor mechanism outwardly with its 
retraction being accomplished by the force of the spring 44. 
The elongate probe positioning member 40 also provides support for a fluid 
flow sensor 48 referred to herein as a "spinner" which is pivotally 
connected at 50 to the probe positioning member 40. In the collapsed 
position of the sensor mechanism 24 it is appropriate for the spinner 48 
to be pivoted into nesting relation within a spinner receptacle 52 that is 
defined by the upper portion of the probe positioning member 40. When the 
sensor positioning mechanism 24 is extended in the manner shown in FIG. 1 
the spinner 48 will be automatically pivoted about its pivot 50 from the 
nesting receptacle 52 to a position being substantially centrally of the 
flow passage within which the tool is received and thus oriented 
substantially parallel with the direction of fluid flow through the flow 
passage. 
Intermediate the extremities of the wall contact member 32 an elongate 
sensor strut 54 has its upper end pivotally connected at 56 while its 
lower end 58 is disposed in pivotal connection with a spring urged drive 
member 60 having a spring 62 which may be in a form of a coil type 
compression spring as shown. The spring 62, like spring 46 is loaded upon 
movement of the sensor positioning mechanism to the collapsed position 
thereof. Upon release of the sensor positioning mechanism from its nested 
relation with the tool body section 22 the spring 62 will move the drive 
member upwardly thereby also moving the pivotal connection 58 upwardly and 
urging the sensor strut member 54 to the angulated position shown in FIG. 
1. 
Upon expansion to the position shown in FIG. 1 the sensor positioning 
mechanism accomplishes de-centralization of the tool body 12 within the 
flow passage and also positions various sensor components in desired 
locations within the fluid passage. The temperature probe 30 and the 
spinner mechanism 48 are located centrally of the flow passage to thus 
properly locate them for sensing. A capacitance probe 64 is located by the 
mechanism so that it extends across the flow passage for sensing of all of 
the various phases of fluid flow within the flow passage. In the 
alternative, the sensor support 54 may be provided with a plurality of 
individual production fluid sensors located in spaced relation along the 
length thereof so that the sensors are each positioned for sensing a 
particular portion of the cross-section of the fluid passage so that all 
phases of the fluid may be sensed. 
It is desirable that when used in deviated wellbores the logging tool be 
capable of becoming oriented so that the tool body 12 is in contact with 
the bottom wall surface portion of the wellbore or conduit while the wall 
contact member 32 is in contact with the upper wall thereof. This is 
accomplished by the influence of gravity acting on the differing weights 
of the tool body 12 and the sensor positioning mechanism 24. The tool body 
12, including its various components, is of significantly greater weight 
compared to the weight of the sensor positioning mechanism 24. The 
influence of gravity on the tool body 12 thereby positions the tool body 
in contact with the lower wall of the inclined or deviated wellbore or 
conduit. Since the sensor positioning mechanism is specifically oriented 
relative to the elongate tool body, the influence of gravity therefore 
also orients the sensor positioning mechanism so that the wall contact 
member 32 is disposed in contact with the upper wall surface portion of 
the wellbore or conduit. The spring enhanced sensor positioning mechanism 
24 expands the sensor mechanism sufficiently to move it into contact with 
the wellbore wall and with sufficient force to accomplish decentralization 
of the logging tool mechanism within the wellbore. Thus the capacitance 
probe and other sensors that may be supported by the sensor support 54 are 
oriented across the wellbore so that all of the phases of the production 
fluid can be sensed. 
Referring now to FIG. 2 an alternative embodiment of the present invention 
is illustrated generally at 70 which is shown to be positioned within a 
well casing 72 extending through a wellbore 74 in an earth formation. The 
production logging tool 70 incorporates an elongate tool body 76 having a 
cut-away portion 78 defining a receptacle for a sensor support mechanism 
shown generally at 81, having a flow housing 80 incorporating an elongate 
capacitance probe 82. The elongate housing 80 is pivotally connected at 
its upper end 84 with a connection mechanism 86 which is disposed in fixed 
relation with the upper portion of the tool body 76. The elongate housing 
80 defines a portion of a capacitance probe linkage mechanism and is 
pivotally connected at its lower end 88 to a sensor support strut 90 which 
in turn has its lower end 92 connected to a sensor drive element 94 that 
is disposed in movable relation with the lower portion of the tool body. 
The sensor drive element 94 is acted upon by a spring 96 which may take 
the form of a compression type coil spring as shown. The lower end of the 
spring 96 is interconnected with a spring retainer 98 which is received 
within the lower end portion 100 of the tool housing structure. The spring 
96 supplies sufficient mechanical force against the capacitance probe 
support 80 to urge one end of the support into engagement with the 
internal wall surface 102 of the well casing 72 and to force the elongate 
tool body 76 into engagement with the opposite wall surface 104 as shown 
in FIG. 2. In this manner, the spring 96 accomplishes decentralization of 
the tool body 76 within the well bore or conduit defining the flow passage 
and positions the lower end 88 of the capacitance probe body 80 so that 
the lower end of the capacitance probe 82 is located in juxtaposition with 
the casing wall surface 102 and the upper end of the capacitance probe is 
located in juxtaposition with the diametrically opposite wall of the 
wellbore. The capacitance probe 82 is therefore located so as to extend 
across the flow passage defined by the wellbore so that in this inclined 
position it can sense all phases of the production fluid which are present 
within the flow passage 106. The sensor mechanism can remain in the 
position shown in FIG. 2 during running of the tool into the casing 72 to 
thus permit the capacitance probe to accomplish fluid sensing on a 
continuous basis as the tool is moved downwardly or upwardly within the 
flow passage. Interconnection of the sensor housing 80 and the sensor 
positioning strut 90, essentially at the pivotal lower end connection 88, 
may be established by a wear plate 108 that resists wear and damage to the 
sensor mechanism of the tool as it is moved along the inside of the well 
casing. As an alternative, as mentioned above the spring assembly may be 
employed to retract or close the sensor mechanism 81 in the absence of 
power. A powered actuator, operating against the closing force of spring 
96, is used to move the sensor mechanism to its open or FIG. 2 position. 
When opening power is discontinued, the closing spring 96 will retract the 
capacitance probe within its receptacle 78 for efficiency of running the 
tool through the wellbore. 
Referring now to FIG. 3, a further alternative embodiment of this invention 
is shown generally at 110 having an elongate tool body structure 112 which 
is shown to be positioned within a well casing 114 extending through a 
wellbore 116 that is drilled within an earth formation. Though shown in 
FIG. 3 as being vertical, the well casing 114 and the wellbore 116 may be 
inclined from the vertical or even horizontal, such as in the case of 
deviated or horizontally drilled wells so that internal casing surface 118 
will represent the top wall of the casing while the diametrically opposite 
well casing surface 120 will be located as the bottom wall. The well 
casing 114 defines a fluid passage 122 within which the production fluid 
is either static or moving. 
The elongate tool body 112 defines an upper connector section 124, a lower 
connector section 126 and an intermediate sensor body section 128 the 
upper and lower connector sections 124 and 126 are provided respectively 
with connector mechanisms 130 and 132 for connection thereof to other 
tools and instruments that may be extended into the wellbore in 
conjunction with the logging process. The connector section 124 is 
provided with a lower connector 134 having connection with the upper end 
of the intermediate body section 128. Likewise, the upper end of the lower 
connector section 126 is provided with an upper connector 136 for 
connection with the lower end of the intermediate body section 128. The 
body section 128 is cut-away as shown at 138 to provide an elongate 
receptacle for receiving an elongate sensor housing 140 that is pivotally 
connected at its upper end 142 to the connector mechanism 134 and is 
pivotal from the extended, angulated position shown in FIG. 3 to a 
position where it is received in nesting relation within the elongate 
receptacle 138 of the tool body. 
When the logging tool 110 is located within the well casing and sensing is 
desired it is appropriate for the elongate sensor housing 140 to be 
pivotally moved from the receptacle 138 to a position where the sensor 
housing extends transversely across the flow passage 122. This feature is 
accomplished by the provision of a bow spring 144 having its upper end 146 
fixed to a movable guide element or slide connector 148 which 
circumscribes the connector section 124 and is slidable along the length 
of the connector section to permit expansion and collapsing of the spring 
144. Likewise the lower end 150 of the bow spring is disposed in 
connection with a slide connector 152 which is movably received about the 
lower connector section 126. The lower end 154 of the elongate sensor 
housing 140 is disposed in actuating contact with the bow spring as shown 
to thereby permit extension or collapsing of the housing 140 as the bow 
spring 144 extends or collapses. If desired, the lower end of the housing 
140 may be defined by a guide roller which establishes a movable, guided 
relation with the bow spring in addition to establishing and actuating 
engagement with the bow spring. An elongate detector element 156 has its 
lower end 158 connected to the sensor housing 140 by means of a pivot 
arrangement 160. Additionally, the upper end 162 of the sensor is provided 
with a guide member 164 which establishes engagement with the bow spring 
144 to ensure positioning of the upper end 162 of the detector in 
juxtaposition with the wall surface 118 of the well casing. The bow spring 
144 is capable of being collapsed by moving its central portion toward the 
sensor receptacle 138. When this movement occurs, the movable slide 
connector elements 148 and 152 will move along the length of the 
respective connector sections 124 and 126 sufficiently to permit the 
amount of spring collapse that is desired. The bow spring will 
automatically extend to the position shown in FIG. 3 when it is not 
otherwise constrained and will have sufficient extension force to induce 
decentralization of the tool body to maintain the tool body and sensor 
mechanism in the position shown in FIG. 3. In this position the sensor 
housing 140 will be inclined so that it is located across the flow passage 
122 so that its sensor assembly defines a sensor array across the 
borehole. The sensor array may be an across-the-borehole capacitance 
sensor of the nature shown at 64 in FIG. 1 or a plurality of individual 
sensors, which may be a plurality of like sensors or a sensor array having 
differing sensors or groups of differing sensors. The sensor or sensor 
array, regardless of its character, will be adequately positioned across 
the borehole and typically oriented from bottom to top in relation to the 
inclined or deviated fluid passage of the wellbore for detection of all 
phases of fluid within the fluid passage 122. Due to the heavier weight of 
the tool body relative to the sensor mechanism, the tool body will 
automatically seek engagement with the bottom wall of the well bore under 
the influence of gravity and will thus orient the sensor mechanism so that 
it engages the top wall of the well bore. 
A further alternative embodiment of this invention is shown generally at 
170 in FIGS. 4 and 5 with FIG. 4 showing the logging tool in its fully 
collapsed condition such as for traversing the well casing or wellbore. 
FIG. 5 illustrates the tool both in its collapsed or running position for 
movement through the wellbore and in its extended or expanded condition 
for decentralizing the tool within the wellbore or well casing and for 
location of the sensors on the high side of an inclined wellbore or well 
casing such as for positioning of a spinner, gamma ray source, density or 
gamma ray detector and a capacitance probe in the region of the high side 
of the flow passage if desired. In vertically oriented wellbores or well 
casings the logging tool provides for location of the spinner, gamma ray 
source detector and capacitance probe adjacent the wall surface of the 
wellbore or well casing. At its upper end the logging tool defines a tool 
support body 172 is having an internal, linearly movable actuator 174 
having its upper end 176 being exposed to receive an upward or downward 
actuating force. The lower end of the actuator element 174 is provided 
with an actuator linkage 178 having operative driving relation with an 
elongate sensor housing 180 having its upper end 182 connected by pivot 
184 to the housing structure. The sensor housing may be provided with a 
temperature sensor 186 which, in the extended condition of the mechanism, 
is located substantially centrally of the flow passage of the well casing 
or other flow conduit. The sensor housing 180 is also shown in FIG. 5 in 
the fully collapsed position thereof. An elongate actuator linkage element 
188 is movably assembled to the lower end 190 of the actuator housing by a 
pivot connection 192. Another actuator link 194 is movably connected to 
the tool housing by a pivot connection 196 at its upper end. The lower end 
of the actuator link 194 is secured by pivot connection 198 to the linkage 
element 188 and is disposed in substantially parallel relation with the 
elongate sensor housing 180. The linkage element 188 is fixed at its lower 
end 200 to a connector mechanism 202 of a sensor housing 204. Thus, upon 
actuation of the mechanism 74-78, the sensor housing 180 is translated 
outwardly or laterally to the offset position shown in FIG. 5, causing the 
linkage struts 188 and 194 to maintain the sensor housing 204 in 
substantially parallel relation with the upper, tool support end 172 of 
the tool body. When the sensor housing 204 is shifted laterally in this 
manner it can be positioned in line contact with or in close proximity to 
the inner wall surface of the well casing or wellbore thereby provided 
efficiency of signal transmission to and from the formation being logged. 
The sensor housing 204 is provided with a spinner 206, a gamma ray or 
other source 208 at its upper end and is provided at its lower end with a 
gamma ray detector 210 and a capacitance probe 212. Operation of the 
logging tools of the various embodiments disclosed herein within an 
inclined or deviated wellbore is depicted in FIG. 6. As shown, the well 
logging tool is illustrated generally at 220 and is shown to be located 
within a deviated well bore 222 which is drilled through an earth 
formation 224. The logging tool 220 with a housing structure shown 
generally at 226 having an upper connector section 228, an electronics 
section 230, a transmitter section 232 and a motor and caliber section 
234. An elongate sensor element or housing 236 is connected by pivot 238 
to the motor and caliper section and is connected at its remote end 240 to 
a wall engaging pad member 242 having therein a gamma ray detector 244 and 
a gamma ray receiver 246. The connection 240 is preferably a pivotal 
connection, thereby permitting the wall contact member 242 to establish 
efficient surface-to-surface engagement with the wall surface of the well 
bore. The opposite end 248 of the wall engaging pad 242 is connected by a 
pivot 250 to a pad positioning strut 252 having its opposite end 254 
establishing pivotal connection with the tool body structure. A source 256 
is provided for sensing the density of the fluid. 
The elongate housing 236 is provided along its length with a plurality of 
sensors or a sensor array to provide signal output relating to desired 
parameters of the well being logged. The sensor array may comprise one or 
more flow rate meters, temperature sensors, capacitance sensors, gamma ray 
detectors, acoustic impedence meters such as shown collectively at 258 for 
the purpose of detecting the condition of the various phases of fluid 
within the flow passage defined by the wellbore. Centrally of the 
wellbore, the housing structure 236 provides a temperature probe 260 for 
accomplishing temperature measurement of the fluid centrally of the 
wellbore. The motor and caliper section 234 accomplishes linear movement 
of a drive element 262 to which the housing structure 236 is pivotally 
connected and thereby is operative to cause expansion or contraction of 
the sensor linkage for the purpose of positioning the pad member 242 into 
efficient contact with the wellbore or retracting the pad member and the 
linkages defined by the housing 236 and link 252 into nested relation 
within a receptacle located in the elongate tool body. Thus, the linkages 
efficiently movable to the position shown in FIG. 6 with sufficient force 
to decentralize the elongate tool body with respect to the wellbore. Since 
the tool body 226 is significantly heavier as compared to the weight of 
the pad 242 and its linkage system 236 and 252, when disposed within a 
deviated wellbore the tool body will become oriented by gravity into 
contact with the lower wall surface 264 of the wellbore while the sensor 
pad 242 will be oriented for engagement with the diametrically opposite 
upper wall surface 266 of the wellbore. 
In view of the foregoing, it is evident that the present invention is one 
well adapted to attain all of the objects and features hereinabove set 
forth, together with other objects and features which are inherent in the 
apparatus disclosed herein. 
As will be readily apparent to those skilled in the art, the present 
invention may be produced in other specific forms without departing from 
its spirit or essential characteristics. The present embodiment, is 
therefore, to be considered as illustrative and not restrictive, the scope 
of the invention being indicated by the claims rather than the foregoing 
description, and all changes which come within the meaning and range of 
the equivalence of the claims are therefore intended to be embraced 
therein.