Wells – Processes – Specific propping feature
Reexamination Certificate
2000-03-02
2001-07-10
Suchfield, George (Department: 3672)
Wells
Processes
Specific propping feature
C166S281000, C166S295000, C507S924000
Reexamination Certificate
active
06257335
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to improved methods of stimulating wells in unconsolidated or poorly consolidated formations, and more particularly, to methods of stimulating hydrocarbon fluid production from such wells while preventing the migration of sand with the fluids produced therefrom.
2. Description of the Prior Art
Oil and gas wells are often completed in unconsolidated formations containing loose and incompetent or poorly consolidated sand which migrates with oil, gas and/or water produced by the wells. The presence of sand in the produced fluids is disadvantageous and undesirable in that the sand particles abrade pumping and other producing equipment and reduce the fluid production capabilities of the produced zones in the wells.
Incompetent subterranean formations include those which contain loose sand that is readily entrained by produced fluids and those wherein the sand particles making up the formations are bonded together with insufficient bond strength to withstand the forces produced by the product of fluids from the formations. A technique which is often used for minimizing sand production from such formations has been to produce fluids from the formations at low flow rates whereby the near well stability of sand bridges and the like in the formations are preserved. However, the collapse of such sand bridges often occurs as a result of unintentional high production rates and/or pressure cycling. Pressure cycling occurs from frequent shut-ins and start ups of a well. The frequency of pressure cycling is very critical to the longevity of the near well formation, especially during the depletion stage of the well when the pore pressure of the formation has already been significantly reduced.
Heretofore, weakly consolidated formations have been treated by creating fractures in the formations and depositing proppant in the fractures to maintain them in open positions. In addition, the proppant has heretofore been consolidated within the fractures into hard permeable masses by hardenable resin compositions to reduce the migration of sand through the fractures with produced fluids. Very often, to insure that sand is not produced, costly gravel packs, sand screens and the like have been installed in the wells. Since gravel packs and sand screens filter out sand from the fluids being produced, the presence of the filtered sand adds to the flow resistance thereby producing additional pressure draw down which causes the fracture faces and other portions of the unconsolidated formations to break down and the consolidated proppant in fractures, gravel packs and the like to be bypassed.
Thus, there is a need for improved methods of stimulating fluid production from unconsolidated permeable formations penetrated by wellbores while preventing the migration of formation sand with fluids produced therefrom.
SUMMARY OF THE INVENTION
The present invention provides improved methods of stimulating fluid production from unconsolidated or weakly consolidated permeable producing formations penetrated by wellbores while preventing the migration of formation sand with fluids produced therefrom. The methods of this invention basically comprise the steps of (a) injecting a liquid composition into a portion of the permeable producing formation surrounding the wellbore which subsequently converts into a gel-like substance and plugs the permeability of the injected portion of the formation, but allows the injected portion to remain flexible and to resist breakdown due to pressure cycling therein; (b) creating at least one fracture in the formation extending from the wellbore through the portion of the formation plugged in accordance with step (a) into an unplugged portion thereof; and (c) depositing hardenable resin composition coated proppant in the fracture and causing the resin composition to harden whereby the proppant is consolidated into a hard permeable mass which filters out and prevents the migration of formation sand with fluids produced through the fracture into the wellbore.
The liquid composition utilized in step (a) to plug the permeability of a portion of the formation can be any of several liquid compositions that cure or convert into a gel-like substance and plug the permeability of the formation. Examples of such liquid compositions include, but are not limited to, organic resin compositions, aqueous sodium silicate compositions and water soluble polymerizable monomer compositions.
The combination of the flexible plugged portion of the formation surrounding the wellbore through which at least one fracture extends and the consolidated permeable proppant in the fracture prevents the migration of sand with produced fluids from the formation.
It is, therefore, a general object of the present invention to provide improved methods of stimulating fluid production from unconsolidated or poorly consolidated permeable producing formations penetrated by wellbores while preventing the migration of formation sand with fluids produced therefrom.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows.
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Brumley John L.
Nguyen Philip D.
Weaver Jimmie D.
Dougherty, Jr. C. Clark
Halliburton Energy Service,s Inc.
Kent Robert A.
Suchfield George
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