Patent Publication Number: US-10774625-B2

Title: Method of producing from a hydrocarbon bearing zone with laterals extending from an inclined main bore

Description:
BACKGROUND 
     1. Field 
     The present disclosure relates to producing oil from a well, and particularly to a method employing multiple laterals extending downward to an oil bearing formation from an inclined section of a main well bore. 
     2. Description of Prior Art 
     Oil may be found in thin formations or zones that overlie a water containing formation. Typically, one or more wells will be drilled into the oil bearing zone. After the well is completed, well fluid from the oil bearing zone flows into the lower part of the well and to the surface. 
     As the well fluid depletes oil from the oil bearing formation, water from the water bearing zone will encroach into the oil bearing zone, increasing the water content of the well fluid flowing up the well. Eventually, the water encroachment will reach a level that results in too much water flowing up the well. Various techniques may then be required to workover the well. 
     SUMMARY 
     A method of wellbore operations comprises drilling a main bore with an inclined section extending toward an earth formation. First and second laterals are drilled from the inclined section, each extending downward from the inclined section into the formation. Openings are provided in the laterals, the opening in the first lateral extending to a greater depth than the opening in the second lateral. Well fluid flows through the openings in the laterals into the inclined section of the main bore. In the event a water content in the well fluid flowing from the opening in the first lateral exceeds a water content in the well fluid flowing from the second lateral by a selected amount, the flow through the opening of the first lateral is selectively restricted relative to the flow from the opening of the second lateral. 
     Drilling the first and second laterals comprises inclining the laterals at a greater angle relative to horizontal than the inclined section of the main bore. 
     Drilling the first and second laterals comprises spacing the first and second laterals apart from each other along a length of the inclined section. 
     In the embodiment shown, drilling first and second laterals comprises inclining each of the laterals at an angle in a range from 45 to 90 degrees relative to horizontal. 
     In one embodiment, drilling first and second laterals comprises positioning an axis of each of the first and second laterals in a vertical plane. 
     Drilling the main bore may comprise blocking the inclined section from a direct entry of well fluid from the formation. 
     In the embodiment shown, the first lateral joins the inclined section at a point closer to an upper end of the main bore than the second lateral. 
     An inflow control device may be installed in the first lateral above the opening in the first lateral. If so, selectively restricting the flow through the opening of the first lateral comprises actuating a valve in the inflow control device. 
     In another embodiment, selectively restricting the flow through the opening of the first lateral comprises sealing at least a lower portion of the opening in the first lateral. 
     The method of wellbore operations may also comprise drilling a main bore with an inclined section extending toward but not opening into a hydrocarbon containing earth formation. A first lateral is drilled from a first junction with the inclined section downward from the inclined section into the formation at a steeper angle than the inclined section. An opening to the formation is provided in the first lateral at a first selected depth. A second lateral is drilled from a second junction with the inclined section downward from the inclined section into the formation at a steeper angle than the inclined section. An opening to the formation is provided in the second lateral to a second selected depth that is shallower than the first selected depth. The second junction is farther from an upper end of the main bore than the first junction. Well fluid flows into the first and second laterals, and from the first and second laterals into the inclined section of the main bore. In response to an increasing water content in the well fluid flowing up the main bore, the flow of well fluid from the first lateral into the inclined section of the main bore is restricted. 
     An inflow control device may be installed in the first lateral. Restricting the well fluid flowing from the first lateral comprises adjusting a valve in the inflow control device. 
     Adjusting the valve in the inflow control device may comprise lowering a tool on a line into the inclined section of the main bore to a position adjacent the inflow control device. A signal is transmitted from the tool to the inflow control device. 
     Alternately, restricting the well fluid flowing from the first lateral comprises installing a seal in the first lateral. 
     Optionally, an upper opening may be provided in the first lateral above the seal, allowing well fluid to flow from upper opening in the first lateral. 
     Drilling first and second laterals may comprise inclining each of the laterals at an angle in a range from 45 to 90 degrees relative to horizontal. 
     The method of wellbore operations may also comprise drilling a main bore with an inclined section extending toward an earth formation. First, second and third laterals may be drilled from the inclined section, each of the first, second and third laterals extending downward from the inclined section at a steeper angle than the inclined section. Openings to the formation are provided in the first, second and third laterals. The opening in the first lateral is at a greater depth than the opening in the second lateral. The opening in the second lateral is at a greater depth than the opening in the third lateral. Well fluid flows from the formation through the openings in the first, second and third laterals into the inclined section of the main bore. Any flow of well fluid from the formation directly into the inclined section of the main bore may be prevented. In response to a water content of the well fluid flowing up the main bore, at least a lower portion of the opening in the first lateral may be restricted, and flow through the openings in the second and third laterals into the inclined section of the main bore may be continued. In response to a subsequent water content of the well fluid flowing up the main bore, at least a lower portion of the opening of the second lateral may be restricted, and flow through the opening in the third lateral into the inclined section of the main bore may be continued. 
     The first, second and third laterals have first, second and third junctions, respectively, with the inclined section. The first junction is shallower than the second junction, and the second junction is shallower than the third junction. 
     Inflow control devices may be installed in the first lateral and in the second lateral. Flow is restricted through the opening in the first lateral by adjusting a valve in the inflow control device in the first lateral. Flow is restricted through the opening in the second lateral by adjusting a valve in the inflow control device in the second lateral. 
     Alternately, flow through the opening in the first lateral may be restricted by installing a seal in the first lateral, blocking the opening in the first lateral. 
     Optionally, an upper opening may be provided in the first lateral above the seal, enabling well fluid to flow through the upper opening into the first lateral. 
     In one embodiment, a well configuration comprises a main bore with an inclined section extending toward an earth formation. First and second laterals each extend downward from the inclined section into the formation. The first lateral has an opening to the earth formation and the second lateral has an opening to the same earth formation. The opening of the first lateral is at a greater depth than the opening of the second lateral. The openings enable well fluid to flow into the laterals and from the laterals into the inclined section of the main bore. 
     In one embodiment, each of the first and second lateral inclines at a greater angle relative to horizontal than the inclined section of the main bore. 
     In one embodiment, each of the first and second laterals has an axis in a vertical plane. 
     The first lateral joins the inclined section uphole from the second lateral in one embodiment. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Some of the features and benefits of the present disclosure having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic sectional view of an example of laterals extending downward from an inclined section of a main wellbore into a hydrocarbon bearing zone. 
         FIG. 2  is a schematic sectional view of the laterals of  FIG. 1  with inflow control devices installed. 
         FIG. 3  is a schematic sectional view of the laterals of  FIG. 1  with a control tool being lowered on a line into the inclined section of the main bore. 
     
    
    
     While the advantages will be described in connection with disclosed embodiments, it will be understood that it is not intended to be limited to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope as defined by the appended claims. 
     DETAILED DESCRIPTION 
     The method and system of the present disclosure will now be described more fully with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term “about” includes +/−5% of the cited magnitude. In an embodiment, usage of the term “substantially” includes +/−5% of the cited magnitude. 
     It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. 
       FIG. 1  schematically illustrates a well having a main bore  11  with a conventional production tree  13  at the upper end. Main bore  11  has a vertical portion extending downward from tree  13  to a curved section or heel  15  that joins an inclined section  17 . Inclined section  17  may be straight, but it inclines downward. The angle of inclination of inclined section  17  may vary and is illustrated to be about 10 to 15 degrees relative to horizontal as an example. Main bore  11 , including its inclined section  17 , may be cased with a casing cemented in place. 
     Inclined section  17  has a lower end or toe  19  that is schematically shown to be a short distance above an earth formation  21  that is a hydrocarbon or oil bearing zone. Inclined section  17  could extend into oil bearing zone  21 , but if so, in this example it is sealed from the well fluid in oil bearing zone  21 . Oil bearing zone  21  is illustrated as overlying an earth formation  23  that is a water bearing zone. Oil bearing zone  21  may contain some interspersed water droplets, but it will also have significant quantities of oil at least initially. Water bearing zone  23  will mostly contain water. 
     Using conventional techniques, the operator drills a first lateral  25  from a first junction with inclined section  17 . First lateral  25  is a bore extending downward from inclined section  17  into hydrocarbon bearing zone  21 . First lateral  25  may also be straight, but it inclines at a much steeper angle than inclined section  17 . As an example, the angle of first lateral  25  relative to horizontal may be 45 to 90 degrees, thus it could be vertical. First lateral  25  has an axis that may be in a vertical plane. 
     First lateral  25  has an opening  27  schematically illustrated that communicates first lateral  25  with the well fluid in oil bearing zone  21 . Opening  27  could be an open hole or uncased portion of lateral  25 . Opening  27  could alternately comprise a tubular screen with apertures. First lateral  25  could be completely cased with casing cemented in place and a casing shoe closing the lower end. In that instance, opening  27  would comprise perforations formed in the casing in a conventional manner. The perforations may extend over a length of first lateral  25 . Regardless of the configuration of opening  27 , its lowest extent, such as its lowest perforation, will be at a selected first depth within oil bearing formation  21 . That first depth will be above water bearing zone  23 . 
     A second lateral  29  joins inclined section  17  at a second junction downhole from the junction of first lateral  25  with inclined section  17 . Second lateral  29  is also a bore extending downward from inclined section  17  into hydrocarbon bearing zone  21 . Second lateral  29  may also be straight and inclining at a much steeper angle than inclined section  17 . In this example, second lateral  29  is parallel with first lateral  25 , thus it is at an angle relative to horizontal of 45 to 90 degrees. Second lateral  29  has an axis that is in the same vertical plane as first lateral  25  in this embodiment. 
     Second lateral  29  has an opening  31  that communicates second lateral  29  with the well fluid in oil bearing zone  21 . Opening  31  could be an open hole or uncased portion of second lateral  29 . Opening  31  could comprise a tubular screen with apertures. Second lateral  29  could be completely cased with casing cemented in place and a casing shoe closing the lower end. In that instance, opening  31  would also comprise a set of perforations made along a length of the casing in second lateral  29  in a conventional manner. Regardless of the configuration of opening  31 , its lowest extent, such as its lowest perforation, will be at a selected second depth within oil bearing formation  21  that is shallower than the depth of the lowest extent of opening  27  in first lateral  25 . That is, the lowest extent of opening  31  is at a higher level in oil bearing zone  21  than the lowest extent of opening  27  in first lateral  27 . The lowest extent of opening  31  is also above water bearing zone  23 . The distance from the lowest extent of opening  31  to the junction of second lateral  29  with inclined section  17  is less than the distance from the lowest extent of opening  27  to the junction of first lateral  25  with inclined section  17 . 
     In this example, a third lateral  33  joins inclined section  17  at a junction closer to inclined section lower end  19  than the junction of second lateral  29  with inclined section  17 . The junction of third lateral  33  with inclined section  17  is downhole from the junction of second lateral  29  with inclined section  17 . Third lateral  33  is also a bore extending downward from inclined section  17  into hydrocarbon bearing zone  21 . Third lateral  33  may also be straight, but it also inclines at a much steeper angle than inclined section  17 , such as 45 to 90 degrees relative to horizontal. In this example, third lateral  33  has an axis that is parallel with the axes of first lateral  25  and second lateral  29 . The axes of first lateral  25 , second lateral  29  and third lateral  33  are in the same vertical plane in this embodiment. 
     Third lateral  33  has an opening  35  that communicates third lateral  33  with well fluid in oil bearing zone  21 . Opening  35  could also be an open hole or uncased portion of third lateral  33 . Opening  35  could comprise a tubular screen with apertures. Third lateral  33  could be completely cased with casing cemented in place and a casing shoe closing the lower end. In that instance, opening  35  would comprise perforations formed along a length of the casing in a conventional manner. Regardless of the configuration of opening  35 , its lowest extent, such as its lowest perforation, will be at a selected third depth within oil bearing formation  21  that is shallower than the depths of the lowest extents of opening  27  in first lateral  25  and opening  31  in second lateral  29 . The lowest extent of opening  35  is above water zone  23  and at a higher level in oil bearing zone  21  than the lowest extent of opening  27  in first lateral  25  and opening  31  in second lateral  29 . The distance from the lowest extent of opening  35  to the junction of third lateral  33  with inclined section  17  is less than the distance from the lowest extent of opening  31  to the junction of second lateral  29  with inclined section  17 . 
       FIG. 2  shows an inflow control device or valve (ICV)  37  installed in an upper portion of first lateral  25 . Second lateral  29  also has an ICV  39 , and third lateral  33  has an ICV  41 . ICV&#39;s  37 ,  39  and  41  may be identical. Each ICV  37 ,  39 ,  41  comprises an assembly with a bore through it containing a valve  43  that opens and closes the bore. Valve  43  could also be a type of a choke that may be adjusted to partially open the bore to meter the flow of well fluid flowing through the bore. In addition, ICV&#39;s  37 ,  39 ,  41  have one or more packer elements  45  that expand into sealing engagement with the side walls of laterals  25 ,  29 ,  33 , forcing all well fluid flowing into laterals  25 ,  29 , and  33  to flow through the bores of the ICV&#39;s. 
     Valves  43  may be electrically powered by a battery.  FIG. 3  illustrates a downhole tool  47  lowered on a line  49 , which may be a wireline or coiled tubing. Tool  47  has a transmitter that will send a wireless signal a short distance through inclined section  17  for receipt by the closest one of the ICV&#39;s  37 ,  39 ,  41 , which is illustrated to be ICV  37 . The signal will actuate valve  43  to open, close, or partially close the bore through ICV  37 . The signal may also be used to re-charge the battery of the particular valve  43 . 
     The lowest extent of each opening  27 ,  31  and  35  will be selected to be initially above any significant level of water within oil bearing zone  21 . Valves  43  may be initially fully open, allowing well fluid that is primarily oil to flow through each ICV  37 ,  39  and  41 . The oil from each lateral  25 ,  29  and  33  flows into inclined section  17  and may commingle as it flows up main bore  11 . In this example, no well fluid flows directly into inclined section  17  other than the well fluid flowing through the three laterals  25 ,  29  and  33 . 
     As the oil is depleted from oil bearing zone  21 , water from water bearing zone  23  will encroach upward into oil bearing zone  21 . If so, the deepest opening  27  should begin experiencing a higher water content than the water contents of the well fluid flowing through the shallower openings  31 ,  35 . The increased water content could be detected by analyzing the commingled flow at production tree  13 . Also, the increased water content in first lateral  25  could separately be detected by the use of a logging tool lowered on a wireline or coiled tubing into inclined section  17 . The logging tool could also separately measure the water contents of the well fluid flowing from second and third laterals  29  and  33 . 
     If merited, the operator would then either close or partially close valve  43  in ICV  37  by lowering tool  47  ( FIG. 3 ) to a point close to ICV  37  and sending a signal to ICV  37 . If the operator completely closes valve  43  in first lateral ICV  37 , all of the well fluid flowing up main bore  11  would be from second and third laterals  29 ,  33 . The operator may choose to partially close valve  43  in first lateral ICV  37 , reducing the flow rate of liquid flowing from first lateral  25 . 
     Eventually, water from water bearing zone  23  may begin encroaching into opening  31  in second lateral  29 . If so, the water content of well fluid flowing from second lateral  29  would likely be higher than the water content of well fluid flowing from third lateral  33  because of the deeper depth of the lowest extent of second lateral opening  31 . The operator may fully or partially close valve  43  in second lateral ICV  39  in the same manner. If closed fully and if first lateral ICV  37  is closed completely, all of the well fluid flowing up wellbore  11  will now be from third lateral  33 . As the water content from third lateral  33  increases, the operator may wish to meter the flow through third lateral  33  by adjusting valve  43  in third lateral ICV  41 . That adjustment could also be performed by lowering tool  47  ( FIG. 3 ). 
     In an alternate method, ICV&#39;s are not employed to restrict flow in the event of higher water content in the well fluid. Instead, the operator may restrict flow through the first lateral  25  by injecting a sealant into first lateral  25 , blocking opening  27 . The sealant may be a conventional chemical, such as cement, crosslinked polymers, resins, silicates and the like. If the opening in first lateral  25  comprises a set of perforations, the operator may choose to seal off only a lower portion of those perforations, allowing well fluid to continue flowing through an upper portion of the set of perforations. Alternately, if the operator does not wish to fully close first lateral  25 , he could perforate casing in the lateral above the sealant through conventional techniques such as shaped charges or water jetting, creating upper openings in first lateral  25 . Well fluid would then flow through the upper openings of first lateral  25 . The same alternate procedures could also be followed to restrict flow through opening  31  in second lateral  29 . 
     Providing multiple laterals extending into the same formation to different depths from an inclined wellbore section has advantages. The multiple laterals reduce early water breakthrough in the well by balancing the pressure distribution along the length of the well. Reducing early water breakthrough delays workover operations that may be needed. 
     The present improvement described is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others that are inherent. While embodiments of the present description have been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These changes will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present disclosure and the scope of the appended claims. For example, although three laterals are shown, only two or more than three could be employed.