Wells – Processes – Placing or shifting well part
Reexamination Certificate
1999-05-28
2001-02-06
Neuder, William (Department: 3672)
Wells
Processes
Placing or shifting well part
C166S185000, C166S334100, C166S334400
Reexamination Certificate
active
06182766
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a diverter apparatus and methods and more particularly to a drill string diverter apparatus which will redirect fluids that have entered a casing string while the casing string is run into a wellbore.
In the construction of oil and gas wells, a wellbore is drilled into one or more subterranean formations or zones containing oil and/or gas to be produced. The wellbore is typically drilled utilizing a drilling rig which has a rotary table on its floor to rotate a pipe string during drilling and other operations. During a wellbore drilling operation, drilling fluid (also called drilling mud) is circulated through a wellbore by pumping it down through the drill string, through a drill bit connected thereto and upwardly back to the surface through the annulus between the wellbore wall and the drill string. The circulation of the drilling fluid functions to lubricate the drill bit, remove cuttings from the wellbore as they are produced and exert hydrostatic pressure on the pressurized fluid containing formations penetrated by the wellbore to prevent blowouts.
In most instances, after the wellbore is drilled, the drill string is removed and a casing string is run into the wellbore while maintaining sufficient drilling fluid in the wellbore to prevent blowouts. The term “casing string” is used herein to mean any string of pipe which is lowered into and cemented in a wellbore including but not limited to surface casing, liners and the like. As is known in the art, the term “liner” simply refers to a casing string having a smaller outer diameter than the inner diameter of a casing that has already been cemented into a portion of a wellbore.
During casing running operations, the casing string must be kept filled with fluid to prevent excessive fluid pressure differentials across the casing string and to prevent blowouts. Heretofore, fluid has been added to the casing string at the surface after each additional casing joint is threadedly connected to the string and the casing string is lowered into the wellbore. Well casing fill apparatus have also been utilized at or near the bottom end of the casing string to allow well fluid in the wellbore to enter the interior of the casing string while it is being run.
One purpose for allowing wellbore fluid to enter the casing string at the end thereof is to reduce the surge pressure on the formation created when the casing string is run into the wellbore. Surge pressure refers to the pressure applied to the formation when the casing being run into the wellbore forces wellbore fluid downward in the wellbore and outward into the subterranean formation. One particularly useful casing fill apparatus is disclosed in U.S. Pat. No. 5,641,021 to Murray et al., assigned to the assignee of the present invention, the details of which are incorporated herein by reference. Although such casing fill apparatus work well to reduce surge pressure, there are situations where surge pressure is still a problem.
Liners having an outer diameter slightly smaller than the inner diameter of casing that has previously been cemented in the wellbore are typically lowered into a partially cased wellbore and cemented in the uncased portion of a wellbore. The liner is lowered into the wellbore so that it extends below the bottom end of the casing into the uncased portion of the wellbore. Once a desired length of liner has been made up, it is typically lowered into the wellbore utilizing a drill string that is connected to the liner with a liner running tool. The liner will typically include a well casing fill apparatus so that as the liner is lowered into the wellbore, wellbore fluids are allowed to enter the liner at or near the bottom end thereof.
Because the drill string has a much smaller inner diameter than the liner, the formation may experience surge pressure as the fluid in the liner is forced to pass through the transition from the liner to the drill string and up the smaller diameter drill string. Thus, there is a continuing need for an apparatus that will reduce the surge pressure on the formation when lowering a liner into a wellbore. Furthermore, because there are circumstances where it is necessary to manipulate the liner, there is a need for an apparatus that in addition to reducing surge pressure will allow for rotational and reciprocal movement and manipulation of the liner in the wellbore while the diverter is locked in a closed position.
SUMMARY OF THE INVENTION
The above-mentioned needs are met by the diverter apparatus of the present invention. The drill string diverter apparatus of the present invention comprises a tubular housing defining a longitudinal central flow passage, and having at least one flow port and preferably a plurality of flow ports defined therethrough intersecting the longitudinal central flow passage. The tubular housing has an upper and lower end with an adapter threadedly connected at each end for connecting to a drill string or other pipe string thereabove and a liner running tool therebelow. A diverter apparatus is connected in the pipe string which is disposed in a wellbore. Preferably, the wellbore has a cased portion having a casing cemented therein. The tubular housing and casing define an annulus therebetween.
The diverter apparatus of the present invention further comprises a means for selectively alternating between an open position wherein fluid may be communicated between the central flow passage and the annulus defined between the tubular housing and the casing in the wellbore through the flow ports, and a closed position wherein communication through the flow ports is blocked. A locking means for locking the diverter apparatus in the closed position to prevent the diverter from being inadvertently alternated back to the open position is also provided.
The means for selectively alternating preferably comprises a closing sleeve slidably disposed along an operating length of the tubular housing. More preferably, the closing sleeve is disposed about an outer surface of the tubular housing and is slidable between the open and closed positions.
The closing sleeve has an outer diameter such that when the diverter apparatus is lowered into the wellbore, the casing disposed therein will engage the closing sleeve and hold the closing sleeve in place. Preferably, the closing sleeve is a closing sleeve assembly comprising a tubular sliding sleeve having a plurality of drag springs disposed about the outer surface thereof. The casing will engage the drag springs and urge the drag springs inwardly so that the sliding sleeve is held in place as the tubular housing, along with the remainder of the drill string, is moved vertically in the wellbore. Typically, the diverter apparatus will be in its open position wherein the sliding sleeve does not cover the flow ports and thus allows communication therethrough during the time the diverter apparatus is lowered into the wellbore. When the tubular housing is lowered into the casing, the casing will engage the drag springs so that the tubular housing will move downwardly as the casing holds the sliding sleeve in place. The flow ports defined through the tubular housing will move downward relative to the sliding sleeve and will remain uncovered such that communication between the annulus and the central opening of the tubular housing is established. The closing sleeve, although it stays stationary along the operating length of the tubular housing can be said to move vertically relative to the tubular housing along the operating length thereof as the tubular housing moves vertically within the casing. Once the sliding sleeve reaches the upper limit of the operating length, it will move downwardly with the tubular housing and will stay in the open position. To move the diverter apparatus from the open to the closed position, downward movement is stopped and an upward pull is applied so that the tubular housing moves upwardly relative to the sliding sleeve until the sliding sleeve reaches the lower end of the operating length,
Duke Wesley G.
Hallman Millard L.
Rogers Henry E.
Stewart Tommy T.
Halliburton Energy Service,s Inc.
Neuder William
Rahhal Anthony L.
Roddy Craig W.
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