Communications: electrical – Wellbore telemetering or control – With orientation sensing of subsurface telemetering equipment
Reexamination Certificate
1998-01-26
2001-05-08
Horabik, Michael (Department: 2635)
Communications: electrical
Wellbore telemetering or control
With orientation sensing of subsurface telemetering equipment
C340S854700, C340S854900, C367S068000, C348S085000
Reexamination Certificate
active
06229453
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
The present invention relates generally to downhole video systems. More particularly, the present invention relates to a downhole video system using standard electrical transmission lines to transmit video. Most particularly, the present invention relates to a downhole video system and method for using standard electrical transmission lines to transmit video and other downhole information to the surface for an improved video depiction of conditions downhole.
Modern society depends upon the inexpensive and continued production of hydrocarbons. In view of a limited world hydrocarbon supply, keeping energy costs low requires continual improvement in well drilling technology. This quest for improved geological formation evaluation and hydrocarbon recovery requires a great quantity of information relating to parameters and conditions downhole. Such information typically includes characteristics of the earth formations traversed by the wellbore, in addition to data relating to the size and configuration of the borehole itself. The collection of information relating to conditions downhole commonly is referred to as “logging”. Logging has been known in the industry for many years as a technique for providing information regarding the particular earth formation being drilled and can be performed by several methods. In conventional oil well wireline logging, a probe or “sonde” is lowered into the borehole after some or all of the well has been drilled, and is used to determine certain characteristics of the formations traversed by the borehole. Various sensors have been used to determine particular characteristics of the formation, including nuclear sensors, acoustic sensors, electrical sensors, and video cameras. The sonde typically is constructed as a hermetically sealed steel cylinder for housing the sensors, which hangs at the end of a long cable or “wireline”. The cable or wireline provides mechanical support to the sonde and also provides an electrical connection between the sensors and associated instrumentation within the sonde, and electrical equipment located at the surface of the well. Normally, the cable supplies operating power to the sonde and is used as an electrical conductor to transmit information signals from the sonde to the surface and control signals from the surface to the sonde. In accordance with conventional techniques, various parameters of the earth's formations are measured and correlated with the position of the sonde in the borehole, as the sonde is pulled uphole.
During drilling and production, a variety of conditions downhole may impede or preclude the retrieval of hydrocarbons from a well bore.
FIG. 1
illustrates a hypothetical well bore
100
and five different levels
110
,
120
,
130
,
140
,
150
of the well bore. A different condition exists at each of these levels. Gas leaks into the well bore at level A
110
, nothing comes into the well bore at level B
120
, oil leaks into the well bore at level C
130
, water leaks into the well bore at level D
140
, and an object
155
occupies the bottom level E
150
of the well bore
100
. Object
155
may, for example, be a piece of equipment that has been mistakenly dropped down the well bore or has been broken.
As can be appreciated by one of ordinary skill in the well drilling arts, a particular hydrocarbon stream, such as oil, is normally sought from a particular well bore. As such, water leakage at level D
140
and gas leakage at level A
110
are not desirable and should be eliminated or minimized, if possible. If the exact depth and character of a gas or water leak can be found, known corrective measures can stop the leaks, and so it is very important to learn the depth and nature of a leak. For obstructions and lost items
155
in the well bore, known “fishing” tools and techniques can usually remove object
155
from the well bore if the object can be seen. Were object
155
left in the well bore, drilling and downhole operations would be complicated and abandonment of the well may be the only option. Because of the extremely high cost of drilling a well bore
100
, it is highly preferable to remove object
155
from the well bore.
Downhole video systems have been found useful in locating and identifying the problems depicted in
FIG. 1
, in addition to others. For example, the video camera system can detect turbulence created by a leak and may identify different fluids leaking into the well bore. Particulate matter flowing out through a hole can be detected. Obstructions in the well bore can be seen. Formation fractures and their orientations may be detected along with damaged, parted, or collapsed tubings and casings. Corrosion surveys can also be performed. Other causes for loss of production, such as sand bridges or malfunctioning flow controls such as valves, may be identified by the downhole video.
FIG. 2
shows one such downhole video system including an instrument probe. Shown are a well logging system
200
including a borehole or well bore
210
and well instrument probe
220
hanging by a support cable
230
. Support cable
230
attaches to rotatable winch
235
, surface controller
240
inside enclosure
245
, and transportable platform
248
. Support cable
230
must be capable of extending through pressure gland
250
, lubricator risers
252
, and main valve
255
, all part of well head
260
.
FIG. 3
illustrates a well instrument probe
220
and attached support cable
230
in a well bore
210
. Also shown are cable head
240
, camera head
250
, light head
260
, and legs
270
attaching lighthead
260
to camera head
250
. The instrument probe
220
contains the remote video camera and other electrical equipment, and connects to the surface by an electrical instrument cable
230
, thereby permitting transmission of electrical power to the video camera and communication of data from the video camera to the surface equipment.
Borehole
210
often is about 21.5 cm (8.5 in) in diameter, but many wells are relatively small in diameter, on the order of 4.5 cm (1.75 in). Consequently, the instrument probe and its cable designated for use in such a well are limited in their respective diameters. This can lead to practical problems when a high pressure well is involved. The well shown in
FIG. 2
is capped to prevent the uncontrolled escape of high pressure well fluids. In order to insert a downhole video instrument into such a well, the video instrument must be forced into the well through the cap. As is well known in the art, small instruments are easier to insert into a high pressure environment because they present less surface area against which the high pressure well fluids can act. Thus, small differences in the diameters of downhole instrument cables can have a tremendous impact on the ease and expense of inserting the cable and an attached instrument into the well. However, small diameter transmission lines typically have severe bandwidth limitations. The prior art attempts to obtain adequate bandwidth between the downhole camera and a surface video monitor by employing co-axial cable or fiber optic cable. However, each of these solutions comes with severe drawbacks.
One drawback of coaxial cable for video transmission is the necessity of a progressively larger coaxial cable for longer well bores. Because the minimization of cable size is highly preferable, thick coaxial cable is not an ideal solution for downhole video transmission. And while fiber optic transmission lines have an adequately small diameter, they are very expensive and have a tendency to break under the severe stresses downhole. Ideally, neither coaxial nor fiber optic transmission lines would be necessary. Instead, the standard electrical transmission lines could be used to obtain satisfactory video at a surface location.
FIG. 4
illustrates a standard electrical transmission and support line used for and connected to a well instrument pr
Gardner Wallace R.
Maddox Steven D.
Conley & Rose & Tayon P.C.
Edwards, Jr. Timothy
Halliburton Energy Service,s Inc.
Horabik Michael
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