Wells – Processes – Placing or shifting well part
Reexamination Certificate
2002-02-08
2004-06-29
Neuder, William (Department: 3672)
Wells
Processes
Placing or shifting well part
C166S066000, C166S254200
Reexamination Certificate
active
06755257
ABSTRACT:
This invention relates to a drillpipe assembly for use in the logging of a borehole that perforates a geological formation. The invention also relates to a method of deploying a logging tool for the logging of such a borehole.
The logging of boreholes is technique well known in the oil and gas industries. The advantages of such an activity are well known to those skilled in the art of oil and gas production.
When a borehole is drilled, it is seldom smooth and regular. Sections of the borehole sometimes cave in. Sometimes there are other sections of rock, in particular shales and clays, that squeeze into the borehole as a result of pressure exerted by overlying strata.
Traditionally, borehole logging has involved the use of a so-called wireline logging tool. The wireline logging tool is lowered on a wireline or pushed on drillpipe into the borehole to a downhole, logging location. The wireline logging tool is connected by a wireline to eg. data processing and recording apparatus at a surface location external of the borehole.
Wireline logging tools are of comparatively large diameter. Consequently it is difficult to push or lower a wireline logging tool into a borehole having caved in or squeezed sections as aforesaid.
In recent years it has become known to employ, for the logging of boreholes, a so-called compact battery/memory logging tool. This logging tool typically is of considerably less diameter than a wireline logging tool. It includes a self-contained power supply in the form of a series of batteries; and one or more memory devices, whose function is to record data logged by the logging tool.
Battery memory logging tools in many circumstances offer advantages over traditional, wireline tools.
The deployment of a battery memory logging tool has hitherto involved securing the tool to the end of a length of drillpipe, such that the logging tool protrudes from the end of the drillpipe; and then driving the tool and drillpipe combination down the borehole, successively adding further lengths of drillpipe at the surface, and forcing the drillpipe assembly into the borehole.
This technique has been necessary because it is important for the logging tool to log the borehole in its openhole condition, ie. when there is no casing or other liner that would interfere with the accuracy of data detection and recording by the tool. Therefore it has hitherto proved necessary to advance the logging tool along the whole length of the borehole to its furthest extremity or total depth (“TD”), with the logging tool protruding from the forwardmost joint of the drillpipe.
The caved in and squeezed sections of the borehole present particular hazards to the deployment of battery memory logging tools in this fashion. The protruding tool can snag and become damaged on such formations.
The caved in and squeezed sections of borehole are particularly prevalent in wells that are significantly deviated from the vertical or horizontal; and also in curved wells.
Furthermore, the likelihood of jamming or damaging a battery memory logging tool during its deployment means that logging engineers tend to deploy the tools at a comparatively slow rate, so as to minimise the risk of damage to the tools. Since rig time is often expensive oil and gas production companies wish to maximise the amount of time spent logging a borehole, as compared with deploying the logging tool. As a result there is scope for improvements in the efficiency of logging tool deployment operations.
It is an aim of the invention to overcome or at least ameliorate one or more of the disadvantages of the prior art apparatuses and methods.
According to a first aspect of the invention, there is provided a drillpipe assembly comprising a drillpipe having secured at a downhole end thereof a delatchable latching sub containing an extendible running sub supporting a logging tool, the running sub being moveable between a first, retracted position, in which it supports the logging tool within one or more stands of drillpipe; and a second, extended position in which it supports the logging tool protruding from the drillpipe, the latching sub, when latched, retaining the running sub in its first position and the latching sub permitting extending of the running sub when delatched.
The use of an apparatus that is capable of holding the logging tool retracted within a joint of drillpipe during deployment, and subsequently extending the logging tool to protrude from the drillpipe, allows deployment of the logging tool without fear that the tool will become snagged, damaged or broken off.
Furthermore, the ability to deploy the logging tool in a retracted condition allows rapid deployment over most of the travel of the logging tool along the borehole. Only at the extreme end of its travel, near the TD of the well, is it necessary to complete deployment of the logging tool at a slow rate.
As a result, the overall logging tool deployment time is significantly reduced. This in turn minimises the amount of rig time that is not used for logging operations.
In a preferred embodiment of the invention, the logging tool is a compact diameter battery memory tool. However, within the scope of the invention it is possible to devise a drillpipe assembly intended to deploy larger diameter tools than the known compact battery memory tools.
Preferably the assembly of the invention includes an hydraulic actuator for extending the running sub.
More specifically, the hydraulic actuator preferably includes one or more seals moveably sealingly interconnecting an outer periphery of the running sub and an inner wall of a drillpipe stand, whereby fluid pressure in the drillpipe acting on one side of a said seal tends to drive the running sub along the drillpipe.
Clearly while the latching sub is latched, there is resistance to movement of the running sub; but when the latching sub is delatched the hydraulic pressure acting on the seals of the running sub conveniently drives the running sub to extend from the downhole end of the drillpipe assembly.
Conveniently the or each said seal is a flexible cup seal sealingly secured to the running sub and in slideable sealing contact with the said drillpipe stand inner wall.
Flexible cup seals (also known as swab cups) are advantageously effective in providing the necessary sealing qualities. Furthermore flexible cup seals are able to accommodate changes in diameter in the internal wall of the drillpipe stand with which they engage. Consequently there is no need to maintain a constant inner diameter of the drillpipe through which the running sub is driveable.
Preferably the running sub defines a closeable fluid flow path bypassing the or each said seal, such that closing of the said path causes fluid pressure in the drillpipe to act on the or each said seal.
In preferred embodiments of the invention the drillpipe assembly includes a pumpable messenger member moveably disposed in the drillpipe. Conveniently the said fluid flow path is closeable by the messenger member.
More specifically, the running sub includes a hollow conduit that is open at either end and defines the aforesaid fluid flow path bypassing the or each said seal. The messenger member includes a sealing member and is insertable into the said conduit at a location uphole of the or each said seal to prevent the flow of fluid via the conduit, thereby closing the said fluid flow path.
Consequently the use of a running sub that includes a fluid flow path; together with a messenger member that is capable of closing the fluid flow path when inserted into the running sub, is an advantageously simple and reliable method of permitting hydraulic pressure in the drillpipe uphole of the running sub selectively to act on the seals thereof to drive the running sub forwardly of the drillpipe itself.
In a preferred embodiment of the invention the messenger member includes a shield that is moveable between a first position in which it obscures the sealing member and a second position in which the sealing member is exposed for sealing of the conduit uphole of the or each said seal of the runni
Ash Simon Christopher
Chaplain Michael John
Spencer Michael Charles
Neuder William
Paul & Paul
Reeves Wireline Technologies Limited
Smith Matthew J
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