Wells – Processes – Placing or shifting well part
Reexamination Certificate
2002-06-25
2004-09-28
Tsay, Frank (Department: 3672)
Wells
Processes
Placing or shifting well part
C166S088100
Reexamination Certificate
active
06796381
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to hydrocarbon production, and in particular, to a pressure control assembly for working pipe in a well under pressure.
BACKGROUND OF THE INVENTION
Conventional petroleum extraction often leaves a significant amount of un-recovered petroleum in petroleum reservoirs. One way to increase recovery is to develop the reservoir with a very high density of producing wells. This option is, however, very expensive and often not economic. One proposal for increasing well density, however, is to drill the producing wells into the reservoir from a subterranean mine excavation located below the petroleum reservoir. Such upward extending wells are often referred to as drain holes, because fluids drain down through the well during production. The economics of drilling wells to a very dense spacing can be more favorable, because each of the producing wells drilled from such a subterranean location will typically be much shorter than wells drilled from a surface location in a conventional manner. This is because the subterranean mine excavation is located much closer to the petroleum reservoir. In addition, expensive drill mud is not needed. Since only water is used to cool the drill bit and there is no backpressure in the drill hole, natural reservoir permeability is not contaminated. Further, drains are produced by gravity, well pumps are not needed. Production through a subterranean mining excavation is potentially an option both for initial development of new reservoirs and for further development of reservoirs that have already been partially depleted by conventional production from production wells drilled from surface locations.
One complication with drilling drain holes and producing petroleum from a subterranean mine excavation located below a petroleum reservoir is that drilling and other well operations must ordinarily be conducted under pressure. Because the drain holes extend in an upward direction, there will always be a positive pressure exerted at the wellhead, which wellhead could be a drilling stack or any other wellhead configuration used for conducting other well operations. This pressure will typically equal the pressure exerted by the reservoir plus the hydrostatic head of fluid filling the drain hole. This is significantly different than conventional operations conducted from a surface location. In the conventional situation, drilling and other well operations are typically conducted without positive pressure at the wellhead, because the well is filled with a liquid that provides a hydrostatic head to counterbalance the reservoir pressure. In the conventional situation, well operations are ordinarily performed under pressure only under upset conditions, such as when there has been a sudden influx of fluid into the wellbore during drilling. As a result, conventional blowout preventers and other conventional wellhead components are typically not designed for normal continuous operation under pressure. These conventional wellhead components are, therefore, typically not well suited for performing drilling or other well operations on drain holes that extend in an upward direction from a subterranean mine excavation, and there is a significant need for improved apparatus and techniques for performing drilling and other operations in such drain holes.
SUMMARY OF THE INVENTION
The present invention addresses the need for performing normal drilling and other well operations under pressure at the wellhead through the use of a special annular sealing structure for sealing the annular space around pipe that is to be manipulated in a well to perform the operation. The sealing structure involves maintenance of a seal between an annular sealing wall and the outside of the pipe in a way that accommodates movement of the pipe under pressure during well operations. In particular, the sealing structure involves a sealing wall with at least one fluid port extending through the sealing wall so that a hydrodynamic bearing fluid is injectable into the annular space between the sealing wall and the outside surface of the pipe. The hydrodynamic bearing fluid helps to maintain a good annular pressure seal while at the same time providing significant lubrication between the sealing wall and the pipe, significantly reducing wear to the sealing wall from manipulation of the pipe during operations performed under pressure.
One aspect of the invention involves a well pressure control assembly. In one embodiment, the well pressure control assembly is operably connectable to a well, typically through a flange connection to well casing, and includes an annular pressure containment structure including the noted sealing structure. The annular pressure containment structure has a passage through which pipe is moved into and out of the well and in which the pipe can be rotated, such as during drilling operations. The annular pressure containment structure includes a sealing wall that defines at least a portion of the passage and includes at least one fluid port extending through the sealing wall adjacent to the passage. When a pipe is received in the passage, hydrodynamic bearing fluid is injectable though the fluid port into the passage adjacent the pipe. In a preferred embodiment, hydrodynamic bearing fluid distributes evenly circumferentially around the pipe so that a liquid film develops between the sealing wall and the pipe, resulting in the development of a hydrodynamic bearing that maintains a standoff between the sealing wall and the pipe.
One alternative for enhancing performance of the annular pressure containment structure is to provide the sealing wall as a flexible wall, such as in the form of a flexible wall of a flexible bladder. The flexible bladder also defines a pressurization cavity within the pressure containment structure that is separated from the passage by the sealing wall. The pressurization cavity is in fluid communication with the passage through the fluid port, so that when the pressurization cavity is pressurized with the hydrodynamic bearing fluid, the hydrodynamic bearing fluid is injected into the passage through the fluid port.
In addition to the annular sealing structure, the annular pressure containment structure is versatile in that any number of different wellhead components can be assembled into the annular pressure containment structure along with the sealing structure to provide various wellhead features for different well operations. For example, the annular pressure containment structure can include components to facilitate circulation of a working fluid and drill cuttings out of the well during drilling operations and for reducing the potential that drill cuttings will detrimentally interfere with operation of the annular sealing structure.
In another aspect, the invention involves a well assembly for drilling or other manipulation of pipe in a well under pressure. In one embodiment, the well assembly includes the annular pressure control assembly operably connected to the well, typically through a flange connection to a casing string, so that the passage through the annular pressure containment structure is aligned with an interior space in the well for communication of pipe through the passage into and out of the well. In one embodiment, the well assembly includes a pipe received in the passage through the annular pressure containment structure, so that the pipe is manipulable under pressure for movement at least translationally into and out of the well and preferably also rotationally about a longitudinal axis of the pipe.
In another aspect, the invention involves a method of manipulating a pipe in a well. In one embodiment, the method includes disposing a distal end of a pipe in a well through the annular pressure containment structure so that a proximal end of the pipe remains outside of the well. The pipe is manipulated while a hydrodynamic bearing fluid is injected adjacent the pipe to help maintain an annular seal around the pipe and to help lubricate between the pipe and the sealing wall. The manipulation of th
Andrews Richard E.
Ayler Maynard F.
Marsh & Fischmann & Breyfogle LLP
Ormexla USA, Inc.
Tsay Frank
LandOfFree
Apparatus for extraction of oil via underground drilling and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for extraction of oil via underground drilling and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for extraction of oil via underground drilling and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3264736