Wells – Processes – Perforating – weakening – bending or separating pipe at an...
Reexamination Certificate
2001-10-22
2003-08-05
Neuder, William (Department: 3672)
Wells
Processes
Perforating, weakening, bending or separating pipe at an...
C166S276000, C166S278000, C166S308400
Reexamination Certificate
active
06601648
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improved method of completing subterranean zones. More specifically, the present invention provides techniques for performing completions in unconsolidated formations to thereby eliminate the need for expensive high-density completion brines and also reduces/eliminates drilling/workover rig requirements for completion operations.
BACKGROUND OF THE INVENTION
The methods described in this patent may be utilized to perform more productive well completions at significantly reduced costs.
Dual-screen assemblies and Frac Packing techniques are known in the art and have been utilized for oil and gas well completions for a number of years. Exemplary embodiments of dual-screen assembly techniques techniques are taught in my previous U.S. Pat. No. 5,722,490, issued Mar. 3, 1998, which is hereby incorporated herein by reference. My previous patent discloses methods for increasing the production rate from a cased well that might otherwise produce solids through perforations during production. In accord with the methods presented in my previous patent, a gravel pack screen is placed in the well along with equipment in the tubing string to control flow from inside to outside the tubing below a production packer. The rig used for handling the tubing string may then be released from the well. The well is then hydraulically fractured. If the well is producing from a high permeability zone, then the hydraulic fracture is preferably formed with a tip screen-out technique. The method can also be used in a well already containing production tubing without moving a rig onto the well to remove the tubing from the well and can be used in a well not yet perforated by adding tubing-conveyed perforating apparatus below the screen.
It is well known by those of skill in the art that oil and gas wells are drilled with a fluid, called drilling mud, which normally has a density greater than water. Typically, after well logs are run to confirm that commercial zones of hydrocarbons have been encountered along the wellbore, steel casing of various sizes is run into the well. The casing is cemented in the wellbore utilizing cementing techniques well known in the art, and then the completion phase of the well commences.
In many areas of the world, the drilling fluids utilized during drilling may permanently damage the pay zone formation adjacent the wellbore in a manner that reduces the potential production of oil and gas. For this reason, a solids-free completion fluid having a selected density is frequently used to displace the drilling fluid from the wellbore as an initial part of the well completion process. Use of a suitable completion fluid is particularly desirable in high permeability, and unconsolidated, formations found throughout the world.
High-density completion fluids are often necessary in conventional well completions to maintain sufficient hydrostatic pressure to control the bottom hole pressures of the producing zones for relatively higher pressure producing zones. However, high-density completion brines can be very expensive, dangerous to field personnel, and often times damaging to the producing zones. Zinc bromide completion fluid, in the density range of 14-20 pounds per gallon, is particularly expensive and damaging. Nonetheless zinc bromide completion fluid is commonly utilized in the prior art despite these known deficiencies because of a lack of more suitable alternatives. Those of skill in the art have focused upon methods and techniques to eliminate the use of zinc bromide completion fluids for many years. Thus, the present invention provides innovative and low-cost solutions to quite significant technical problems encountered for many years by those of skill in the art of well completions.
The technique of Frac Packing a production zone to bypass the damage created by the drilling fluid, and cementing operations, has become the prevalent completion technique utilized for unconsolidated formations. Frac Packing has replaced gravel packing, and high-rate water packing, as the most efficient means to produce these types of pay zones, without the production of formation sand. Normally, the Frac Pack technique results in the highest completion rates, with the lowest drawdown at the formation/wellbore interface.
The elimination, or time reduction, of the use of a drilling rig or workover rig, or other type of well intervention device, e.g., a coiled tubing unit, has a significant effect on the cost of completing an oil or gas well. The rig time required to perform a conventional well completion on unconsolidated zones can be extensive and costly. As used herein a rig is a device with a high lifting capacity capable of lifting an entire string of tubing or pipe, which may have a length of over several thousand feet in length. The rig also includes pipe-handling means for breaking/making pipe connections as the tubular string is removed and/or inserted into the wellbore. Various types of rigs may include jack-up rigs, masts, workover rigs, upright derricks with traveling blocks, drilling rigs, and the like including associated pipe-handling devices. The cost of the rig, coupled with the use of high-density completion brine, can easily result in a non-economical operation. By eliminating or reducing these costs in accord with the techniques of the present invention, many oil and gas wells may now be profitable to drill and complete that otherwise would not be profitable. Moreover, the present invention has the potential to significantly increase profitability of otherwise profitable wells.
Various inventors have attempted to solve problems related to those discussed above as indicated by the following patents:
U.S. Pat. No. 6,095,245, issued Aug. 1, 2000, to M. J. Mount, discloses a repositionable apparatus for perforating and gravel packing an underground well which uses gravity or other means to reposition the apparatus instead of a conventional wireline or work string attached to a rig. Perforating and packing can be accomplished without a rig after the apparatus is initially placed and set in the well. One embodiment of the inventive apparatus uses a perforating gun assembly, a connected ported sub above the gun assembly, a translating annulus packer above the ported sub, a circumferential screen located above the packer, blank pipe connected above the screen, an openable port above the blank tubular pipe, and a second translating annulus packer attached to the blank tubular.
U.S. Pat. No. 6,253,851, issued Jul. 3, 2001, to D. E. Schroeder, discloses method of completing a well that penetrates a subterranean formation and more particularly to a method for screen placement during proppant packing of formation perforations or fractures created by hydraulic fracturing techniques. The top of the screen is placed at a sufficient distance below the top of the perforations such that the frac pack pumping rate does not bridge off at the top of the screen when the frac pack is being pumped.
U.S. Pat. No. 6,003,600, issued Dec. 21, 1999, to Nguyen et al., discloses methods of completing unconsolidated subterranean zones penetrated by wellbores. The methods basically comprise the steps of placing a slotted liner in the zone, isolating the slotted liner and the wellbore in the zone, injecting a hardenable resin composition coated particulate material into the zone by way of the slotted liner and then causing the hardenable resin composition to harden whereby the particulate material is consolidated into a hard permeable uniform mass.
U.S. Pat. No. 5,115,860, issued May 26, 1992, to Champeaux, et al., discloses an apparatus for setting a gravel pack in an oil well through tubing situation and includes the steps of running a tool body into the well using an electric wireline deployment. The tool body is precisely positioned relative to the surrounding casing, and radially extending members attached to the tool are used to extend from the tool body and center the tool body in the well bore. Sand control media such as a gravel pack is disposed in
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