Boring or penetrating the earth – Boring without earth removal – Combined with earth removal
Reexamination Certificate
2002-04-08
2004-03-30
Tsay, Frank (Department: 3672)
Boring or penetrating the earth
Boring without earth removal
Combined with earth removal
C175S058000
Reexamination Certificate
active
06712158
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and apparatus for selective coring or drilling, with particular application to recovering core samples from potential water, oil or gas reservoirs.
BACKGROUND OF THE INVENTION
Extracting core samples from downhole wells is an important aspect of the drilling process to provide geological and geophysical data to establish reservoir models.
Conventionally, core samples of a borehole are recovered from the bottom of a borehole during the drilling phase by means of a bit attached to the lower end of a core barrel which is further attached to the lower end of the drill string.
Sidewall cores may also be recovered during or after the logging phase, and a known method for obtaining side wall cores is described in our UK Patent No 2305953B. The conventional method of recovering borehole core samples typically produces long undisturbed samples which are preferred to the short, often highly fractured samples produced by the sidewall coring method, and it is desirable to increase the quality of the sidewall samples.
The accurate positioning of known coring apparatus is also difficult, frequently resulting in samples of limited value being recovered from geological zones of little interest.
Moreover, the equipment currently available to remove sidewall core samples tends to be somewhat cumbersome and expensive.
A further limitation of the prior art is the method of piercing the well bore lining to allow ingress of production fluids. Wells are conventionally lined with a section of metal tubing which is perforated to allow fluid to enter into the borehole.
These perforations are normally formed in a violent manner by setting off an explosive charge to fire projectile(s) through liner or by the explosive charge itself being designed to blast through the material. The lining is thereby ruptured and perforations are thus formed. However, such a method results in compression of the rock formation surrounding the perforation, reducing its pore size and creating a local barrier to fluid flows around, and significantly, into the borehole. The lining rupture caused by the explosive charge is also relatively uncontrolled and creates a random shape which is not streamlined and requires higher fluid energy to negotiate the perforation.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided apparatus for creating a hole in a subsurface formation. The apparatus includes an inner assembly adapted for connection to an elongate member. The inner assembly is adapted to be raised and lowered within a borehole. The inner assembly includes a member capable of engaging either an outer assembly or the borehole.
According to a second aspect of the invention there is provided a method for creating a hole in a subsurface formation. The method comprises the steps of:
connecting an inner assembly to an elongate member, said inner assembly including a member capable of engaging either of an outer assembly or a borehole;
lowering the inner assembly within the borehole;
engaging the member with either of the outer assembly or the borehole to resist substantially vertical movement of at least a portion of the inner assembly with respect to at least one of the outer assembly or the borehole; and;
driving a cutting member into said subsurface formation to create a hole.
Preferably, the method is performed using the apparatus according to the first aspect of the invention.
The subsurface formation may be a casing, liner or subterranean formation.
Preferably, the method further comprises drilling a hole in a casing of a borehole, typically prior to drilling a hole in the subterranean formation.
The cutting member may be a drill bit. Preferably, the drill bit engages the lining of the borehole at a point proximate to the producing zones. Alternately or in addition, the drill bit preferably engages the borehole and punctures a hole therein.
In one embodiment the inner assembly also comprises a coring barrel.
A rotation resistance mechanism is preferably further provided to prevent rotation of at least a portion of the inner assembly with respect to at least one of the outer assembly or borehole.
Preferably, the member capable of engaging either the outer assembly or the borehole is an expandable member.
Preferably the outer assembly is incorporated into a tubular string comprising a side exit mandrel. Preferably the outer assembly is secured in said borehole before the inner apparatus is lowered therein. Typically, the tubular string is a drill string.
Preferably the expandable member engages the outer assembly. Preferably the expandable member is an inflatable member. Typically the expandable member is formed from rubber and metal and preferably has a high friction coefficient.
Preferably the inner assembly comprises a piston cylinder and preferably a piston rod member. Preferably the piston rod member extends through the piston cylinder, then typically through a rotation resistance mechanism and may connect to spacers below the rotation resistance mechanism. The coring barrel is preferably connected to the lower (opposite) end of the spacers if used or the rotation resistance mechanism if no spacers are used. Typically a drill bit is connected to the coring barrel to engage the geological formation.
Preferably, the rotation resistance mechanism comprises a locking mechanism which locks the piston rod member in a rotational direction with respect to the piston cylinder.
Preferably the elongate member is attached to a wireline head. Preferably the wireline head comprises a sacrificial weak link between the elongate member and the wireline head. Preferably the elongate member comprises electrical conductors and cable. Preferably the electrical conductors transfer communication and/or power from the surface of the borehole to the wireline head, or from the wireline head to the surface.
Preferably the wireline head is attached to a housing. Preferably the housing comprises a valve block, a hydraulic pump, power pack and fluid reservoir. Preferably the housing is also attached to the piston rod member.
Preferably the power pack comprises an electric motor, most preferably a low amperage electric motor. Preferably the electric motor is connected to electrical conductors of the elongate member. Preferably the housing also has an electronics carrier which is also attached to electrical conductors of the elongate member. Typically, the elongate member is a wireline.
Preferably the motor is activated from the surface, through the electrical conductors, to drive the hydraulic pump to transfer fluid from the reservoir into the piston cylinder.
Preferably the cylinder and inflatable member are connected by two fluid flow control means which may be valves. Typically, one valve permits fluids to transfer from the cylinder to the inflatable member and the second valve permits fluids to travel in the opposite direction, that is from the inflatable member to the cylinder. Typically either valve may be closed to resist transfer of fluids. Optionally the valves may be opened by actuation thereof, or alternatively when a specified fluid pressure is attained.
Preferably the main hub part of the piston cylinder is separated into two portions, typically by a piston attached to the piston rod assembly.
Preferably fluids can be injected or rejected from each portion of the main hub part of the piston cylinder. Preferably a first hydraulic line connects to the first, upper, portion of the main hub part of the piston cylinder and a second hydraulic line connects to the second, lower, portion of the main hub part of the piston cylinder. Typically each hydraulic line connects to the hydraulic pump and fluid reservoir. Typically fluid flow control means are provided to control the fluid travelling in the hydraulic lines between the reservoir/pump and each portion of the main hub part of the piston cylinder. Preferably the rate and direction of the fluid may be controlled by the fluid control means. Preferably the fluid control means are valves. Preferably t
Corpro Systems Limited
Drinker Biddle & Reath LLP
Tsay Frank
LandOfFree
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