Hydraulic Fracture Initiation and Propagation Control in Unconsolidated and Weakly Cemented Sediments

Abstract

A method and apparatus for initiating and propagating a vertical hydraulic fracture in unconsolidated and weakly cemented sediments from a single bore hole to control the fracture initiation plane and propagation of the hydraulic fracture, enabling greater yield and recovery of petroleum fluids from the formation. An injection casing with multiple fracture initiation sections is inserted and grouted into a bore hole. A fracture fluid carrying a proppant is injected into the injection casing and opens the fracture initiation sections to dilate the formation in a direction orthogonal to the required fracture azimuth plane. Propagation of the fracture is controlled by limiting the fracture fluid injection rate during fracture initiation and propagation and maintaining a minimum fracture fluid viscosity. The injection casing initiation section remains open after fracturing providing direct hydraulic connection between the production well bore, the permeable proppant filled fracture and the formation.

1 . A method for creating a vertical hydraulic fracture in a formation of unconsolidated and weakly cemented sediments, comprising: 
 a. drilling a bore hole in the formation to a predetermined depth;    b. installing an injection casing in the bore hole at the predetermined depth;    c. dilating the injection casing and the formation in a preferential direction;    d. injecting a fracture fluid into the injection casing with sufficient fracturing pressure to initiate a vertical fracture at an azimuth orthogonal to the direction of dilation;    e. limiting the rate of fracture fluid injection to initiate the hydraulic fracture so that Re is less than 1; and    f. maintaining the fracturing fluid viscosity to be greater than 100 centipoise at the initiated fracture fluid shear rate.    
   
   
       2 . The method of  claim 1 , wherein the method further comprises: 
 a. installing the injection casing at a predetermined depth in the bore hole, wherein an annular space exists between the outer surface of the casing and the bore hole,    b. filling the annular space with a grout that bonds to the outer surface of the casing, wherein the casing has multiple initiation sections separated by a weakening line so that the initiation sections separate along the weakening line under the fracturing pressure.    
   
   
       3 . The method of  claim 2 , wherein the fracture fluid dilates the casing, grout annulus and the formation to initiate the fracture in the formation at a weakening line.  
   
   
       4 . The method of  claim 2 , wherein a mandrel splits the casing and dilates the casing, grout annulus and the formation and the fracture fluid initiates the fracture in the formation at a weakening line.  
   
   
       5 . The method of  claim 1 , wherein the fracture fluid is a water based fracturing gel.  
   
   
       6 . The method of  claim 1 , wherein the fracture fluid is an oil based fracturing gel.  
   
   
       7 . The method of  claim 1 , wherein the fracture fluid comprises a proppant.  
   
   
       8 . The method of  claim 1 , wherein the fracture fluid comprises a proppant, and the fracture fluid is able to carry the proppant of the fracture fluid at low flow velocities.  
   
   
       9 . The method of  claim 7 , wherein the fracture fluid comprises a proppant which has a size ranging from #4 to #100 U.S. mesh, and the proppant is selected from a group consisting of sand, resin-coated sand, ceramic beads, synthetic organic beads, glass microspheres, resin coated proppant and sintered minerals.  
   
   
       10 . The method of  claim 1 , wherein the fracture fluid comprises a proppant and a proppant flowback-retention agent.  
   
   
       11 . The method of  claim 10 , wherein the fracture fluid comprises a proppant flowback-retention agent, which is selected from a group consisting of natural organic fibers, synthetic organic fibers, glass fibers, carbon fibers, ceramic fibers, inorganic fibers, and metal fibers.  
   
   
       12 . The method of  claim 1 , wherein the fracture fluid is clean breaking with minimal residue.  
   
   
       13 . The method of  claim 1 , wherein the fracture fluid has a low friction coefficient.  
   
   
       14 . The method of  claim 1 , wherein the fracture fluid pumping rate and the fracturing fluid viscosity are maintained during fracture propagation to ensure that Re is less than 2.5 at the fracture tip and the fracture fluid viscosity is maintained to be greater than 100 centipoise at the fracture tip.  
   
   
       15 . The method of  claim 1 , wherein the fracture fluid injection rate, pressure and proppant loading is selected so as to promote a screening out of the fracture at the tip to create a wide fracture.  
   
   
       16 . The method of  claim 1 , wherein the casing system enables controlling the rate of fracture fluid injection into each individual opposing wing of the initiated and propagating hydraulic fracture thereby controlling the geometry of the hydraulic fracture.  
   
   
       17 . The method of  claim 2 , wherein the initiation sections remain separated after dilation of the casing by the fracture fluid to provide hydraulic connection of the fracture with the well bore following completion of hydraulic fracturing.  
   
   
       18 . The method of  claim 2 , wherein the fracture fluid comprises a proppant and the initiation sections each contain well screen sections separating the proppant in the hydraulic fracture from the production well bore and thus preventing proppant from flowing back from the fracture into the production well bore during fluid extraction.  
   
   
       19 . The method of  claim 1 , wherein the method further comprises re-fracturing of each previously injected fracture.  
   
   
       20 . The method of  claim 1 , wherein the casing is two thirds the height of the completed interval to be hydraulically fractured.  
   
   
       21 . The method of  claim 1 , wherein the casing is one half the height of the completed interval to be hydraulically fractured.  
   
   
       22 . The method of  claim 1 , wherein the casing is one third the height of the completed interval to be hydraulically fractured.  
   
   
       23 . The method of  claim 1 , wherein a screen and gravel pack is completed inside of the casing.  
   
   
       24 . The method of  claim 3 , wherein the casing comprises two initiation sections with two directions of dilation.  
   
   
       25 . The method of  claim 3 , wherein the casing comprises two initiation sections with two directions of dilation and the first and second weakening lines are orthogonal.  
   
   
       26 . The method of  claim 24 , wherein the casing system enables controlling the rate of fracture fluid injection into each individual opposing wing of the initiated and propagating hydraulic fractures thereby controlling the geometry of the hydraulic fractures.  
   
   
       27 . The method of  claim 24 , wherein the casing is two thirds the height of the completed interval to be hydraulically fractured.  
   
   
       28 . The method of  claim 24 , wherein the casing is one half the height of the completed interval to be hydraulically fractured.  
   
   
       29 . The method of  claim 24 , wherein the casing is one third the height of the completed interval to be hydraulically fractured.  
   
   
       30 . The method of  claim 24 , wherein the initiation sections remain separated after dilation of the casing by the fracture fluid to provide hydraulic connection of the fracture with the well bore following completion of hydraulic fracturing.  
   
   
       31 . The method of  claim 24 , wherein the fracture fluid comprises a proppant and the initiation sections each contain well screen sections separating the proppant in the hydraulic fracture from the production well bore and thus preventing proppant from flowing back from the fracture into the production well bore during fluid extraction.  
   
   
       32 . The method of  claim 24 , wherein a screen and gravel pack is completed inside of the casing.  
   
   
       33 . The method of  claim 3 , wherein the casing comprises three initiation sections with three directions of dilation.  
   
   
       34 . The method of  claim 33 , wherein the casing system enables controlling the rate of fracture fluid injection into each individual opposing wing of the initiated and propagating hydraulic fractures thereby controlling the geometry of the hydraulic fractures.  
   
   
       35 . The method of  claim 33 , wherein the casing is two thirds the height of the completed interval to be hydraulically fractured.  
   
   
       36 . The method of  claim 33 , wherein the casing is one half the height of the completed interval to be hydraulically fractured.  
   
   
       37 . The method of  claim 33 , wherein the casing is one third the height of the completed interval to be hydraulically fractured.  
   
   
       38 . The method of  claim 33 , wherein the initiation sections remain separated after dilation of the casing by the fracture fluid to provide hydraulic connection of the fracture with the well bore following completion of hydraulic fracturing.  
   
   
       39 . The method of  claim 33 , wherein the fracture fluid comprises a proppant and the initiation sections each contain well screen sections separating the proppant in the hydraulic fracture from the production well bore and thus preventing proppant from flowing back from the fracture into the production well bore during fluid extraction.  
   
   
       40 . The method of  claim 33 , wherein the method further comprises re-fracturing of each previously injected fracture.  
   
   
       41 . The method of  claim 33 , wherein a screen and gravel pack is completed inside of the casing.  
   
   
       42 . The method of  claim 3 , wherein the casing comprises four initiation sections with four directions of dilation, with the first and second weakening lines being orthogonal to each other and the third and fourth weakening lines being orthogonal to each other.  
   
   
       43 . The method of  claim 42 , wherein the casing system enables controlling the rate of fracture fluid injection into each individual opposing wing of the initiated and propagating hydraulic fractures thereby controlling the geometry of the hydraulic fractures.  
   
   
       44 . The method of  claim 42 , wherein the casing is two thirds the height of the completed interval to be hydraulically fractured.  
   
   
       45 . The method of  claim 42 , wherein the casing is one half the height of the completed interval to be hydraulically fractured.  
   
   
       46 . The method of  claim 42 , wherein the casing is one third the height of the completed interval to be hydraulically fractured.  
   
   
       47 . The method of  claim 42 , wherein the initiation sections remain separated after dilation of the casing by the fracture fluid to provide hydraulic connection of the fracture with the well bore following completion of hydraulic fracturing.  
   
   
       48 . The method of  claim 42 , wherein the fracture fluid comprises a proppant and the initiation sections each contain well screen sections separating the proppant in the hydraulic fracture from the production well bore and thus preventing proppant from flowing back from the fracture into the production well bore during fluid extraction.  
   
   
       49 . The method of  claim 42 , wherein the method further comprises re-fracturing of each previously injected fracture.  
   
   
       50 . The method of  claim 42 , wherein a screen and gravel pack is completed inside of the casing.  
   
   
       51 . The method of  claim 1 , wherein the dilation of the formation is achieved by first cutting a vertical slot in the formation at the required azimuth for the initiated fracture, injecting a fracture fluid into the slot with a sufficient fracturing pressure to dilate the formation in this preferential direction and thereby initiate a vertical fracture at an azimuth orthogonal to the direction of dilation; controlling the flow rate of the fracture fluid and its viscosity so that Re less than 1 at fracture initiation and less than 2.5 during fracture propagation and the fracture fluid viscosity is greater than 100 centipoise at the fracture tip.  
   
   
       52 . A well in a formation of unconsolidated and weakly cemented sediments, comprising a bore hole in the formation to a predetermined depth; an injection casing in the bore hole at the predetermined depth; a source for delivering a fracture fluid into the injection casing with sufficient fracturing pressure to dilate the injection casing and the formation and initiate a vertical fracture with a fracture tip at an azimuth orthogonal to the direction of dilation, wherein the injection casing further comprises: 
 a. multiple initiation sections separated by a weakening line and    b. multiple passages within the initiation sections and communicating across the weakening line for the introduction of the fracture fluid to dilate the casing and separate the initiation sections along the weakening line, wherein the passages to each opposing wing of the fracture are connected to the source of fracture fluid to dilate the injection casing and the formation in a preferential direction and thereby initiate the vertical fracture at the azimuth orthogonal to the direction of dilation and to control the propagation rate of each individual opposing wing of the hydraulic fracture, and    the source delivers the fracture fluid at a flow rate with an Re of less than 1 at fracture initiation and less than 2.5 during fracture propagation and wherein the fracture fluid has a viscosity greater than 100 centipoise at the fracture tip.    
   
   
       53 . The well of  claim 52 , wherein the fracture fluid is a water based fracturing gel.  
   
   
       54 . The well of claim  521 , wherein the fracture fluid is a oil based fracturing gel.  
   
   
       55 . The well of  claim 52 , wherein the fracture fluid comprises a proppant.  
   
   
       56 . The well of  claim 52 , wherein the fracture fluid comprises a proppant, and the fracture fluid is able to carry the proppant of the fracture fluid at low flow velocities.  
   
   
       57 . The well of  claim 56 , wherein the fracture fluid comprises a proppant which has a size ranging from #4 to #100 U.S. mesh, and the proppant is selected from a group consisting of sand, resin-coated sand, ceramic beads, synthetic organic beads, glass microspheres, resin coated proppant and sintered minerals.  
   
   
       58 . The well of  claim 52 , wherein the fracture fluid comprises a proppant and a proppant flowback-retention agent.  
   
   
       59 . The well of  claim 58 , wherein the fracture fluid comprises a proppant flowback-retention agent, which is selected from a group consisting of natural organic fibers, synthetic organic fibers, glass fibers, carbon fibers, ceramic fibers, inorganic fibers, and metal fibers.  
   
   
       60 . The well of  claim 52 , wherein the fracture fluid is clean breaking with minimal residue.  
   
   
       61 . The well of  claim 52 , wherein the fracture fluid has a low friction coefficient.  
   
   
       62 . The well of  claim 52 , wherein the fracture fluid injection rate, pressure, and proppant loading is selected so as to promote a screening out of the fracture at the tip to create a wide fracture.  
   
   
       63 . The well of  claim 52 , wherein the initiation sections remain separated after dilation of the casing by the fracture fluid to provide hydraulic connection of the fracture with the well bore following completion of hydraulic fracturing.  
   
   
       64 . The well of  claim 52 , wherein the fracture fluid comprises a proppant and the initiation sections each contain well screen sections separating the proppant in the hydraulic fracture from the production well bore and thus preventing proppant from flowing back from the fracture into the production well bore during fluid extraction.  
   
   
       65 . The well of  claim 52 , wherein the method further comprises re-fracturing of each previously injected fracture.  
   
   
       66 . The well of  claim 52 , wherein the casing is two thirds the height of the completed interval to be hydraulically fractured.  
   
   
       67 . The well of  claim 52 , wherein the casing is one half the height of the completed interval to be hydraulically fractured.  
   
   
       68 . The well of  claim 52 , wherein the casing is one third the height of the completed interval to be hydraulically fractured.  
   
   
       69 . The well of  claim 52 , wherein a screen and gravel pack is completed inside of the casing.  
   
   
       70 . A well in a formation of unconsolidated and weakly cemented sediments, comprising a bore hole in the formation to a predetermined depth; an injection casing in the bore hole at the predetermined depth, the injection casing comprising multiple initiation sections separated by a weakening line, passages within the initiation sections communicate a fracture fluid to each opposing wing of a selected weakening line, wherein each weakening line corresponds to one of a plurality of fracture planes; and a source for delivering the fracture fluid with sufficient pressure to separate the initiation sections adjacent the selected weakening lines, dilate the formation, and initiate a fracture with a fracture tip in the formation along the desired fracture plane, and controlling the flow rate of the fracture fluid and its viscosity so that Re is less than 1 at fracture initiation and less than 2.5 during fracture propagation and the fracture fluid viscosity is greater than 100 centipoise at the fracture tip.  
   
   
       71 . A well in a formation of unconsolidated and weakly cemented sediments, comprising a bore hole in the formation to a predetermined depth; an injection casing in the bore hole at the predetermined depth, the injection casing comprising multiple initiation sections separated by a weakening line, passages within the initiation sections communicate a fracture fluid to each opposing wing of a selected opposed pair of weakening lines, wherein each opposed pair of weakening lines corresponds to one of a plurality of desired fracture planes; and a source for delivering the fracture fluid with sufficient pressure to separate the initiation sections adjacent the selected opposed pairs of weakening lines, dilate the formation, and initiate a fracture with a fracture tip in the formation along the desired fracture plane, and controlling the flow rate of the fracture fluid and its viscosity so that Re is less than 1 at fracture initiation and less than 2.5 during fracture propagation and the fracture fluid viscosity is greater than 100 centipoise at the fracture tip.