CA2684049C - Infill well methods for sagd well heavy hydrocarbon recovery operations - Google Patents
Infill well methods for sagd well heavy hydrocarbon recovery operations Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/2406—Steam assisted gravity drainage [SAGD]
Abstract
Infill well methods for Steam Assisted Gravity Drainage (SAGD) well heavy hydrocarbon recovery operations are provided. In one implementation, an infill well is provided in a residual zone defined between two SAGD steam chamber areas through a method involving determining boundaries of the residual zone and drilling an infill bore in the residual zone along a trajectory determined based on the boundaries. A method for recovering heavy hydrocarbons from such a residual zone including operating an infill well positioned in the residual zone along a trajectory based on boundaries is also provided. The residual zone may include one or more hump zone or vertically unbroken zone. The drilling of an infill bore may involve drilling a horizontal main bore and multilateral branch bores.
Description
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INFILL WELL METHODS FOR SAGD WELL HEAVY HYDROCARBON RECOVERY
OPERATIONS
FIELD
[0001] The present invention relates to the field of providing, completing and operating infill wells in steam assist gravity drainage (SAGD) heavy hydrocarbon recovery operations.
BACKGROUND
INFILL WELL METHODS FOR SAGD WELL HEAVY HYDROCARBON RECOVERY
OPERATIONS
FIELD
[0001] The present invention relates to the field of providing, completing and operating infill wells in steam assist gravity drainage (SAGD) heavy hydrocarbon recovery operations.
BACKGROUND
[0002] Extraction of bitumen from oil sands ore generally includes mining the ore, crushing the mined ore and then forming an aqueous oil sands slurry including the crushed ore for hydrotransport to a bitumen extraction operation.
[0003] In the bitumen extraction operation, the aqueous oil sands slurry can be supplied to a primary separation vessel that produces a primary bitumen froth stream, a middlings stream and a tailings stream containing water and coarse mineral solids. The middlings stream and the tailings stream can be supplied to additional separation vessels, which are often flotation cells, in order to recover additional bitumen. The bitumen froth can be further de-aerated to remove air, and combined with a diluent to aid removal of mineral solids and water and to produce a high quality bitumen for further upgrading operations.
[0004] The bitumen extraction operation produces various tailings streams that can include coarse mineral solids, fine mineral solids, water and residual bitumen. Tailings can be disposed of or subjected to further treatments and separations prior to disposal.
Tailings can be supplied to tailings ponds for containment of the tailings, settling of the solids, and enabling surface water to be recycled back into the bitumen extraction operation.
Tailings can be supplied to tailings ponds for containment of the tailings, settling of the solids, and enabling surface water to be recycled back into the bitumen extraction operation.
[0005] Tailings ponds can contain significant quantities of unrecovered bitumen.
However, recovering bitumen from tailings ponds and other tailings sources has a number of challenges.
However, recovering bitumen from tailings ponds and other tailings sources has a number of challenges.
[0006] SAGD has become a widespread process of recovering heavy oil and bitumen particularly in the oil sands of Northern Alberta. The SAGD process involves well pairs each of which consists of two horizontal wells drilled in the oil sands and aligned in . CA 02684049 2014-03-26 spaced relation one on top of the other. The upper well is a steam injection well and the lower well is a producer well. The injected steam forms a steam chamber that grows upward and outward within the formation, heating the bitumen or crude oil sufficiently to reduce its viscosity and allow it to flow toward the producer well along with condensed water.
[0007] Numerous SAGD well pairs are usually provided in groups extending from central pads for hundreds of meters. The well pairs of a group often extend parallel generally parallel to one another.
[0008] As the SAGD process evolves over time, the steam chamber of each well pair increases in size and may change in shape. The steam chambers generally progress upward and outward, leaving low-lying bypassed regions along either side of each well pair. However, the steam chambers can often be irregularly shaped and defining a correspondingly irregular infill region. The SAGD process in fact leaves a significant amount of residual bitumen or heavy oil in the infill regions between and below SAGD
producers at the end of its economic life. Infill wells have been proposed to recover some of this residual hydrocarbon.
producers at the end of its economic life. Infill wells have been proposed to recover some of this residual hydrocarbon.
[0009] Some strategies have been proposed to access the infill region by drilling single offset wells. In one known process, as described in US patent No. 6,257,334 (Cyr et al.) and colloquially known as Fast-SAGD, an offset well is provided and operated at cyclic steam stimulation to establish communication with the SAGD well pair and then converted to a production mode under steam trap control. In anther known process, as described in US patent No. 7,556,099 (Arthur et al.), an infill producer well is located and operated in a bypassed region in between two well pairs that form a common mobilised zone above the infill well before establishing fluid communication between the infill well and the common mobilised zone.
[0010] The known processes for providing infill wells in mature SAGD recovery fields have a variety of disadvantages related to the speed, efficiency, conformance to residual zones and completeness of the recovery.
[0011] There is thus a need for a technology that overcomes at least some of the disadvantages of what is known in the field.
SUMMARY
SUMMARY
[0012] The present invention responds to the above-identified need by providing methods of infill well completion for SAGD recovery fields.
[0013] Accordingly, the present invention provides a method for providing a generally horizontal infill well in an elongated residual zone defined between two SAGD
well pairs.
The residual zone is surveyed and mapped, preferably by 4D seismic methods, to determine its boundaries selected from overlying, underlying, flanking and internal lithological boundaries. An infill bore is then drilled in the residual zone along a trajectory conforming to the boundaries. The infill well is then completed in conformance with the boundaries and operated to ameliorate bitumen or heavy oil recovery through the infill well. The overlying boundary may consist of overburden areas and SAGD steam chamber areas, the underlying boundary comprises underburden, the flanking boundaries comprise steam chambers of neighbouring SAGD well pairs, and the internal lithological boundaries may comprise pockets or strata of oil-barren rock depending on the given geological formation under development.
well pairs.
The residual zone is surveyed and mapped, preferably by 4D seismic methods, to determine its boundaries selected from overlying, underlying, flanking and internal lithological boundaries. An infill bore is then drilled in the residual zone along a trajectory conforming to the boundaries. The infill well is then completed in conformance with the boundaries and operated to ameliorate bitumen or heavy oil recovery through the infill well. The overlying boundary may consist of overburden areas and SAGD steam chamber areas, the underlying boundary comprises underburden, the flanking boundaries comprise steam chambers of neighbouring SAGD well pairs, and the internal lithological boundaries may comprise pockets or strata of oil-barren rock depending on the given geological formation under development.
[0014] The surveillance of the residual zone's boundaries and the adjustment of infill well drilling, completion and operation to conform to the boundaries of the residual zone, improves the heavy oil recovery operation in mature SAGD operations.
[0015] In one aspect, the method comprises:
surveying a residual zone to determine an underburden boundary;
drilling an infill well bore in the residual zone so as to comprise:
a low-lying sump bore section below the underburden boundary between heels of the SAGD well pairs; and an upper bore section communicating with the low-lying bore section and extending above and along the underburden boundary topward the toes of the SAGD well pairs;
completing the infill well such that a downhole pump is located in the low-lying bore section and a production liner section is located in the upper bore section.
surveying a residual zone to determine an underburden boundary;
drilling an infill well bore in the residual zone so as to comprise:
a low-lying sump bore section below the underburden boundary between heels of the SAGD well pairs; and an upper bore section communicating with the low-lying bore section and extending above and along the underburden boundary topward the toes of the SAGD well pairs;
completing the infill well such that a downhole pump is located in the low-lying bore section and a production liner section is located in the upper bore section.
[0016] This downhole pump location notably allows the infill well to maximize hydrocarbon recovery potential from the residual zone, benefit from a longer economic life, facilitate the hydrocarbon transport from the toe toward the heel of the infill well, and diminish the risk of steam breakthrough near the pump location throughout the infill well operational evolution.
[0017] In another aspect, the method comprises:
surveying the residual zone to determine hump zones and a vertically unbroken zones in between the two SAGD well pairs, wherein:
each hump zone is defined by an overlying and flanking steam chamber boundaries;
each vertically unbroken zone is defined by an overburden boundary and flanking steam chamber boundaries;
drilling a horizontal infill well bore in the residual zone through the hump zones and the vertically unbroken zones to avoid steam breakthrough; and completing the infill well such that in the hump zone steam breakthrough is avoided from the flanking and overlying steam boundaries and in the unbroken zone steam breakthrough is avoided from the flanking boundaries, optionally via perforation and blank arrangements in the liner.
surveying the residual zone to determine hump zones and a vertically unbroken zones in between the two SAGD well pairs, wherein:
each hump zone is defined by an overlying and flanking steam chamber boundaries;
each vertically unbroken zone is defined by an overburden boundary and flanking steam chamber boundaries;
drilling a horizontal infill well bore in the residual zone through the hump zones and the vertically unbroken zones to avoid steam breakthrough; and completing the infill well such that in the hump zone steam breakthrough is avoided from the flanking and overlying steam boundaries and in the unbroken zone steam breakthrough is avoided from the flanking boundaries, optionally via perforation and blank arrangements in the liner.
[0018] In yet another aspect, the method comprises:
surveying the residual zone to determine a hump zone defined by an overlying and flanking steam chamber boundaries, to determine an offset distance between the overlying steam chamber boundary and a projected infill well bore trajectory along the hump zone, thereby identifying a latent steam breakthrough location;
drilling a horizontal infill well in the hump zone;
completing the infill well such that the completion proximate the latent steam breakthrough location comprises reduced inflow, optionally via blanks or reduced size perforations or slots.
surveying the residual zone to determine a hump zone defined by an overlying and flanking steam chamber boundaries, to determine an offset distance between the overlying steam chamber boundary and a projected infill well bore trajectory along the hump zone, thereby identifying a latent steam breakthrough location;
drilling a horizontal infill well in the hump zone;
completing the infill well such that the completion proximate the latent steam breakthrough location comprises reduced inflow, optionally via blanks or reduced size perforations or slots.
[0019] In still another aspect, the method comprises:
surveying the residual zone to determine reservoir lows and elevated hydrocarbon accumulations as well as steam chamber boundaries proximate such reservoir lows and such oil accumulations;
drilling an infill well bore in the residual zone to comprise a main horizontal bore along the residual zone and multilateral branch bores extending into the reservoir lows and oil accumulations, such that the multilateral branch bores are spaced away from the steam chamber boundaries by an offset distance;
completing the infill well so as to comprises a main production well and branch side wells, such that the branch side wells are sufficiently distant to avoid steam breakthrough therein;
operating the branch side wells to maintain conformance, optionally by avoiding steam breakthrough via liners comprising blanks or varied perforation size or frequency, or by encouraging steam fingering.
surveying the residual zone to determine reservoir lows and elevated hydrocarbon accumulations as well as steam chamber boundaries proximate such reservoir lows and such oil accumulations;
drilling an infill well bore in the residual zone to comprise a main horizontal bore along the residual zone and multilateral branch bores extending into the reservoir lows and oil accumulations, such that the multilateral branch bores are spaced away from the steam chamber boundaries by an offset distance;
completing the infill well so as to comprises a main production well and branch side wells, such that the branch side wells are sufficiently distant to avoid steam breakthrough therein;
operating the branch side wells to maintain conformance, optionally by avoiding steam breakthrough via liners comprising blanks or varied perforation size or frequency, or by encouraging steam fingering.
[0020] In another aspect, the method comprises:
surveying the residual zone to determine flanking steam chamber boundaries defining its respective flanks;
drilling an infill well in the residual zone to comprise a main horizontal bore along the residual zone and multilateral branch bores which are each spaced away from the flanking steam chamber boundaries by a common offset distance;
completing the infill well so as to comprise a main well and branch side wells;
operating the infill well such that the main well comprises blanks and varied perforations and the branch side wells blanks and varied perforations, so as to avoid steam breakthrough from the flanking boundaries.
surveying the residual zone to determine flanking steam chamber boundaries defining its respective flanks;
drilling an infill well in the residual zone to comprise a main horizontal bore along the residual zone and multilateral branch bores which are each spaced away from the flanking steam chamber boundaries by a common offset distance;
completing the infill well so as to comprise a main well and branch side wells;
operating the infill well such that the main well comprises blanks and varied perforations and the branch side wells blanks and varied perforations, so as to avoid steam breakthrough from the flanking boundaries.
[0021] In another aspect, the method comprises:
surveying the residual zone to determine flanking steam chamber boundaries defining its respective flanks;
drilling an infill well in the residual zone to comprise a main horizontal bore along the residual zone and multilateral branch bores which are each spaced away from the flanking steam chamber boundaries by a common offset distance;
completing the infill well so as to comprise a main well and branch side wells;
operating each branch side wells to cause growth of steam fingers away from the flanking boundaries toward the corresponding branch side wells.
surveying the residual zone to determine flanking steam chamber boundaries defining its respective flanks;
drilling an infill well in the residual zone to comprise a main horizontal bore along the residual zone and multilateral branch bores which are each spaced away from the flanking steam chamber boundaries by a common offset distance;
completing the infill well so as to comprise a main well and branch side wells;
operating each branch side wells to cause growth of steam fingers away from the flanking boundaries toward the corresponding branch side wells.
[0022] In another aspect, which may combined with any one of the above aspects, the method further comprises:
performing time-lapse surveillance of the residual zone to determine the evolution of at least one of its boundaries, thereby determining a predicted boundary for a given stage of the infill well drilling, completion or operation;
adjusting the drilling, completion or operation of the infill well according to the predicted boundary of the residual zone to avoid of steam breakthrough.
performing time-lapse surveillance of the residual zone to determine the evolution of at least one of its boundaries, thereby determining a predicted boundary for a given stage of the infill well drilling, completion or operation;
adjusting the drilling, completion or operation of the infill well according to the predicted boundary of the residual zone to avoid of steam breakthrough.
[0023] In one instance, the flanking steam chamber boundaries are subjected to time-lapse surveillance after drilling and prior to completion of the infill well, and the predicted flanking boundary is determined to have an area that will impinge upon a previously planned slotted section of the well completion liner. The liner arrangement is adjusted accordingly so as to comprise a blank liner in the predicted impingement area of the flanking boundary.
[0024] In another instance, the flanking steam chamber boundaries are subjected to time-lapse surveillance before drilling the infill bore, and the predicted flanking boundary is determined to have an area that will impinge upon a previously planned bore trajectory. The drilling is adjusted accordingly so as to bypass the predicted impingement area of the flanking boundary. Preferably, a second predicted flanking boundary is determined to adapt the completion of the infill well.
[0025] In another instance, the flanking steam chamber boundaries are subjected to time-lapse surveillance to determine predicted steam impingement areas along the infill well trajectory. The infill well is then completed with inflow control devices proximate the predicted steam impingement areas. During recovery of heavy hydrocarbons through the infill well in production mode, the recover characteristics are appraised and time-lapse surveillance is performed to revise downhole flow conditions using the inflow control devices. Preferably, the inflow is reduced in the main or branched parts of the infill well in areas proximate the predicted steam impingement areas prior to steam breakthrough.
Preferably, the operation based on predicted boundaries is performed to achieve uniform production along the infill well.
Preferably, the operation based on predicted boundaries is performed to achieve uniform production along the infill well.
[0026] In some implementations, there is provided a method for providing a generally horizontal infill well in an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas for recovery of heavy hydrocarbons, the method comprising:
determining boundaries of the residual zone, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
drilling an infill bore in the residual zone along a trajectory determined based on the boundaries; and completing an infill well in the infill bore; and wherein the infill well is configured to recover heavy hydrocarbons from the residual zone.
determining boundaries of the residual zone, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
drilling an infill bore in the residual zone along a trajectory determined based on the boundaries; and completing an infill well in the infill bore; and wherein the infill well is configured to recover heavy hydrocarbons from the residual zone.
[0027] In some implementations, the infill well is further configured such that heat provided by the two SAGD chamber areas facilitates the recovery of heavy hydrocarbons.
[0028] In some implementations, the step of determining boundaries of the residual zone comprises performing four-dimensional seismic surveillance of the residual zone.
[0029] In some implementations, the process includes, for at least one boundary of the residual zone, predetermining an offset distance between the boundary and the infill well; and determining the trajectory of the infill bore to be spaced away from each of the at least one boundary by at least the corresponding offset distance.
[0030] In some implementations, at least one boundary for which an offset distance is determined is defined by the SAGD steam chamber areas.
[0031] In some implementations, predetermining the offset distance comprises selecting a distance that is sufficient in order to avoid steam breakthrough from one of the SAGD
steam chamber areas into the infill bore.
steam chamber areas into the infill bore.
[0032] In some implementations, predetermining the offset distance comprises selecting a distance that is sufficient in order to encourage steam to grow from one of the SAGD
steam chamber areas toward the infill well.
steam chamber areas toward the infill well.
[0033] In some implementations, the process includes identifying a latent steam breakthrough location from one of the SAGD steam chamber areas into the infill well.
[0034] In some implementations, the completing of the infill well further comprises providing reduced inflow completion proximate the latent steam breakthrough location.
[0035] In some implementations, the reduced inflow completion comprises blank liners.
[0036] In some implementations, the reduced inflow completion comprises liners comprising reduced size perforations or reduced size slots.
[0037] In some implementations, the step of drilling the infill bore comprises providing a low-lying sump bore section positioned below an underlying boundary of the residual zone.
[0038] In some implementations, the underlying boundary comprises underburden between heels of SAGD well pairs.
[0039] In some implementations, the step of completing the infill well further comprises providing a downhole element located in the low-lying bore section.
[0040] In some implementations, the step of drilling the infill bore further comprises an upper bore section communicating with the low-lying sump bore section and extending above and along the underlying boundary toward toes of the SAGD well pairs.
[0041] In some implementations, the step of completing the infill well further comprises providing a production liner section located in the upper bore section.
[0042] In some implementations, the production liner comprises a slotted liner.
[0043] In some implementations, the drilling of the infill bore comprises determining the trajectory so as to be spaced away from the flanking boundaries defined by the SAGD
steam chamber areas, by an offset distance that is substantially the same on either side of the trajectory.
steam chamber areas, by an offset distance that is substantially the same on either side of the trajectory.
[0044] In some implementations, the offset distance is selected in order to be sufficient to avoid steam breakthrough from the SAGD steam chamber areas into the infill well.
[0045] In some implementations, the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication.
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication.
[0046] In some implementations, the residual zone comprises:
at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and , opposed flanking steam boundaries defined by the SAGD steam chamber areas.
at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and , opposed flanking steam boundaries defined by the SAGD steam chamber areas.
[0047] In some implementations, drilling the infill bore comprises drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores.
[0048] In some implementations, the process includes drilling the multilateral branch bores at regularly spaced intervals.
[0049] In some implementations, the process includes drilling the multilateral branch bores so as to be spaced away from the SAGD steam chamber areas by an offset distance selected in order to be sufficient to avoid steam breakthrough from the SAGD
10 steam chamber areas into the infill well.
10 steam chamber areas into the infill well.
[0050] In some implementations, the process includes drilling the multilateral branch bores at a toe end of the residual zone.
[0051] In some implementations, drilling the infill bore comprises drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores in the vertically unbroken residual zone.
[0052] In some implementations, completing the infill well comprises completing a main well in the main bore; and completing branch side wells in the branch bores.
[0053] In some implementations, the branch side wells are configured to encourage growth of steam fingers from the SAGD steam chamber areas.
[0054] In some implementations, the branch side wells are configured to avoid steam breakthrough from the SAGD steam chamber areas into the branch side wells.
[0055] In some implementations, completing the infill well comprises providing the branch side wells with a liner.
[0056] In some implementations, the liner is slotted or perforated. In some implementations, liner comprises slots or perforations of varied size or frequency.
[0057] In some implementations, completing the infill well comprises providing the infill well with a blank liner section.
[0058] In some implementations, the blank liner section is provided proximate to a boundary defined by one of the SAGD steam chamber areas.
[0059] In some implementations, determining boundaries of the residual zone comprises time-lapse monitoring of the residual zone to determine the evolution of at least one of the boundaries; and determining at least one predicted boundary for a stage of the drilling of the infill well and/or the completing of the infill well.
[0060] In some implementations, the process includes adjusting the drilling of the infill well and/or the completing of the infill well according to the at least one predicted boundary of the residual zone.
[0061] In some implementations, the at least one predicted boundary of the residual zone is defined by the SAGD steam chamber areas and further defined by a predicted steam impingement area within at least one of the SAGD chamber areas, and the adjusting is performed to provide sufficient offset distance between the infill bore and/or the infill well from the predicted steam impingement area to avoid steam breakthrough into the infill bore and/or the infill well.
[0062] In some implementations, the adjusting of the completion of the infill well comprises providing the infill well with an inflow control device proximate the predicted steam impingement area.
[0063] In some implementations, the process further includes recovering the heavy hydrocarbons through the infill well in production mode; monitoring recovery characteristics of the infill well and/or evolution of at least one of the boundaries of the residual zone; and adjusting downhole flow conditions using the inflow control devices in accordance with the recovery characteristics and/or the evolution of at least one of the boundaries of the residual zone.
[0064] In some implementations, the step of drilling the infill bore comprises adapting the trajectory according to baseline topology of the underlying boundary.
[0065] In some implementations, the baseline topology of the underlying boundary is undulating.
[0066] In some implementations, the drilling of the infill bore is adjusted based on azimuthal resistivity.
[0067] In some implementations, the drilling of the infill bore is adjusted based on density measurements.
[0068] In some implementations, there is provided a method for recovering heavy hydrocarbons from an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas, the method comprising:
operating an infill well positioned in the residual zone along a trajectory based on determined boundaries, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
wherein the operating comprises producing heavy hydrocarbons from the infill well to recover heavy hydrocarbons from the residual zone.
operating an infill well positioned in the residual zone along a trajectory based on determined boundaries, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
wherein the operating comprises producing heavy hydrocarbons from the infill well to recover heavy hydrocarbons from the residual zone.
[0069] In some implementations, the infill well bore comprises a low-lying sump bore section positioned below an underlying boundary of the residual zone, wherein the underlying boundary comprises underburden between heels of SAGD well pairs.
[0070] In some implementations, the infill well comprises a downhole pump element that is located in the low-lying bore section.
[0071] In some implementations, the infill well bore further comprises an upper bore section communicating with the low-lying sump bore section and extending above and along the underlying boundary toward toes of the SAGD well pairs.
[0072] In some implementations, the infill well comprises a production liner section that is located in the upper bore section.
. CA 02684049 2014-03-26 [0073] In some implementations, the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication.
. CA 02684049 2014-03-26 [0073] In some implementations, the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication.
[0074] In some implementations, the residual zone comprises:
at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas.
at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas.
[0075] In some implementations, the trajectory of the infill well is located with at least one offset distance from at least one of the boundaries of the residual zone defined by the SAGD steam chamber areas, the at least one offset distance being sufficient in order to avoid steam breakthrough from one of the SAGD steam chamber areas into the infill well.
[0076] In some implementations, the at least one offset distance is sufficient in order to encourage steam to grow from one of the SAGD steam chamber areas toward the infill well [0077] In some implementations, the infill well comprises reduced inflow completion proximate a latent steam breakthrough location from one of the SAGD steam chamber areas into the infill well.
[0078] In some implementations, the reduced inflow completion comprises blank liners.
[0079] In some implementations, the reduced inflow completion comprises liners comprising reduced size perforations or reduced size slots.
[0080] In some implementations, the trajectory of the infill well is spaced away from the flanking boundaries defined by the SAGD steam chamber areas by an offset distance that is substantially the same on either side of the trajectory.
[0081] In some implementations, the offset distance is selected in order to be sufficient to avoid steam breakthrough from the SAGD steam chamber areas into the infill well.
[0082] In some implementations, the infill well comprises a horizontal main well along the length of the residual zone; and multilateral branch wells extending from the main well into the residual zone.
[0083] In some implementations, the multilateral branch wells are provided at regularly spaced intervals.
[0084] In some implementations, the multilateral branch wells extend at an offset distance with respect to the SAGD steam chamber areas selected to be sufficient in order to avoid steam breakthrough from the SAGD steam chamber areas into the infill well.
[0085] In some implementations, the multilateral branch wells are located at a toe end of the residual zone.
[0086] In some implementations, the multilateral branch wells are located in a vertically unbroken residual zone.
[0087] In some implementations, the multilateral branch wells are configured to encourage growth of steam fingers from the SAGD steam chamber areas.
[0088] In some implementations, the multilateral branch wells are configured to avoid steam breakthrough from the SAGD steam chamber areas into the multilateral branch wells.
[0089] In some implementations, the multilateral branch wells comprise a liner.
[0090] In some implementations, the liner is slotted or perforated.
[0091] In some implementations, the liner comprises perforations of varied size or frequency.
[0092] In some implementations, the multilateral branch wells comprise a blank liner section.
[0093] In some implementations, the blank liner section is provided proximate to a boundary defined by one of the SAGD steam chamber areas.
[0094] In some implementations, the method includes adjusting the operation of the infill well according to at least one predicted boundary of the residual zone, the at least one predicted boundary being determined by time-lapse monitoring of the residual zone.
10 [0095] In some implementations, the at least one predicted boundary of the residual zone is defined by a predicted steam impingement area of the SAGD steam chamber areas.
[0096] In some implementations, the adjusting of the operation of the infill well comprises controlling inflow proximate the predicted steam impingement area.
[0097] In some implementations, the process includes adjusting downhole flow conditions using inflow control devices in accordance with recovery characteristics and/or evolution of at least one of the boundaries of the residual zone.
[0098] In some implementations, the operating of the infill well further comprises injecting steam into the infill well to enhance mobility of the hydrocarbons in the residual zone.
[0099] In some implementations, the operating of the infill well further comprises alternating between production and steam injection modes to enhance mobility of the hydrocarbons in the residual zone.
[0100] In some implementations, there is provided a method for recovering heavy hydrocarbons from an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas, the method comprising:
operating an infill well positioned in the three-dimensional residual zone defined by boundaries that vary along a length dimension of the residual zone, wherein the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas; and flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chamber areas defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication; and at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas;
wherein the infill well comprises a completion in the at least one hump zone configured to avoid steam breakthrough into the infill well; and wherein the operating comprises producing heavy hydrocarbons from the infill well.
[0101] In some implementations, there is provided a method for providing an infill well in an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas for recovery of heavy hydrocarbons, the method comprising:
drilling an infill bore in the residual zone along a trajectory based on boundaries of the residual zone, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
wherein the drilling comprises:
drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores extending from the main bore into the residual zone;
completing an infill well in the infill bore;
wherein the infill well is configured to recover heavy hydrocarbons from the residual zone.
[0102] In some implementations, the process includes drilling the multilateral branch bores at regularly spaced intervals.
[0103] In some implementations, the process includes drilling the multilateral branch bores so as to be spaced away from the SAGD steam chamber areas by an offset distance selected so as to be sufficient in order to avoid steam breakthrough through the multilateral branch bores.
[0104] In some implementations, the offset distance is substantially the same for each of the multilateral branch bores.
[0105] In some implementations, the offset distance is sufficient in order to allow encouragement of steam growth from the SAGD steam chamber areas toward the multilateral branch bores when the infill well is operated.
[0106] In some implementations, the process includes drilling the multilateral branch bores at a toe end of the residual zone.
[0107] In some implementations, the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication; and at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas; and wherein the method further comprises drilling the multilateral branch bores to extend into the vertically unbroken residual zone.
[0108] In some implementations, completing the infill well comprises completing a main well in the main bore; and completing branch side wells in the multilateral branch bores.
[0109] In some implementations, the branch side wells are configured to encourage growth of steam fingers from the SAGD steam chamber areas toward the branch side wells.
[0110] In some implementations, the branch side wells are configured to avoid steam breakthrough from the SAGD steam chamber areas.
[0111] In some implementations, the branch side wells comprise a liner. In some implementations, the liner is slotted or perforated. In some implementations, the liner comprises perforations of varied size or frequency.
[0112] In some implementations, the branch side wells comprise a blank liner section.
[0113] In some implementations, the blank liner section is provided proximate to a boundary defined by one of the SAGD steam chamber areas.
[0114] In some implementations, the branch side wells are at an oblique angle with respect to the main well.
[0115] In some implementations, the branch side well sections extend obliquely toward a toe end of the residual zone.
[0116] In some implementations, the branch side wells comprise completions allowing injection and production.
[0117] In some implementations, the branch side wells extend to recover lows or oil accumulations in the residual zone.
[0118] In some implementations, the process includes controlling the branch side wells with inflow control devices.
[0119] In some implementations, the drilling of the infill well comprises drilling junctions of the multilateral branch bores and the main horizontal bore in competent rock below the reservoir.
BRIEF DESCRIPTION OF THE DRAWINGS
[0120] Figs la-le are plan view schematics of single SAGD well pairs with steam chambers in dotted lines.
[0121] Figs 2a-2b are lateral cross-sectional view schematics of SAGD well pairs with steam chambers in dotted lines.
[0122] Figs 3a-3b are perspective view schematics of sections of residual zones formed between neighbouring SAGD well pairs.
[0123] Fig 4a-4e are perspective view schematics of different types of residual zones formed between neighbouring SAGD well pairs.
[0124] Fig 5 is a longitudinal cross-sectional view schematic, with vertical dimension exaggerated, of an infill well with a downhole sumped pump.
[0125] Fig 6 is a longitudinal cross-sectional view schematic, with vertical dimension exaggerated, of an infill well with a blank liner proximate a steam chamber boundary.
[0126] Fig 7 is a perspective isolation view schematic of neighbouring SAGD
well pairs and an in-between infill well with a main section and branched side sections.
[0127] Fig 8 is a block diagram flow chart.
[0128] Fig 9 is a seismic plan view image representing a residual zone in between neighbouring SAGD well pairs and an infill well. The warmer colours represent the presence of steam, while the "anomaly" in blue is a vertically unbroken zone.
[0129] Fig 10 is a seismic longitudinal cross-sectional image from line X.
10 [0130] Fig 11 is a seismic lateral cross-sectional image along line Xl.
DETAILED DESCRIPTION
[0131] The infill completion methods of the present invention allow improved conformance to complex infill lithology, base topography and neighbouring steam chamber boundaries in an accurate and adaptive manner.
[0132] Unlike prior techniques, which understate or overlook the complex three-dimensional and constantly evolving nature of SAGD residual zones for infill opportunities, the methods of the present invention take into account the three-dimensional boundaries of such residual zones.
[0133] Referring to Figs la-le, a given SAGD well pair 20 can generate a variety of 20 steam chambers 22 or mobilised hydrocarbon zones, with different plan view shapes and orientations.
[0134] Referring to Figs 2a-2b, when two SAGD well pairs 20 are located beside each other, their steam chambers 22 usually grow upward and outward. Depending on their separation distance, the operation of the SAGD well pairs and the lithology of the formation, the steam chambers 22 can remain separate as shown in Fig 2a or they may join together form a common steam chamber as shown in Fig 2b.
[0135] Referring now to Fig 3a, when the steam chambers remain separate, the resulting residual zone may be referred to as a "vertically unbroken zone" 24.
This type of zone often has an elongated shape with an overlying boundary following the overburden, an underlying boundary following the underburden topology and flanking boundaries which are often concave defined by the adjacent steam chambers.
[0136] Referring to Fig 3b, when the steam chambers of neighbouring SAGD well pairs coalesce to form a common steam chamber, the resulting residual zone may be referred to as a "hump zone" 26. This type of zone often has an elongated shape with an underlying boundary following the underburden topology, while the overlying and flanking boundaries are both defined by the common steam chamber.
[0137] Referring now to Figs 4a-4e, various combinations of hump zones 26 and vertically unbroken zones 24 can co-exist along a single infill residual zone 30. Each of these scenarios calls for a corresponding adapted infill well.
[0138] Referring to Figs 5-7, a horizontal infill well 31 is provided in the residual zone 30.
[0139] Referring to Fig 5, there may be provided a low point in the infill well trajectory in the underburden 32. A downhole pump 34 may be sited at the low point. The infill well 31 is completed in reservoir, e.g. with a slotted liner 36. The infill well 30 may be provided approximately parallel to and midway between the neighbouring SAGD
well pairs, depending on steam configuration. The downhole pump and well trajectory are preferably adapted to the baseline topology.
[0140] Referring to Fig 6, which shows a similar strategy to that of Fig 5, the completion include a liner with a blank section 38 proximate to the steam chamber boundary. It should be understood that the steam chamber boundary may be determined by seismic surveying, preferably using a time-lapse seismic method which can allow a predicted steam chamber boundary and thus foresee certain problematic locations along the infill well. Depending on the timing of the seismic surveying (before or after drilling, completion or operation), the infill well can be adapted accordingly.
[0141] Referring to Fig 7, the infill well may include a main section 40 and multilateral branch sections 42,44. The multilateral branches target reservoir lows and oil accumulations, for example. The infill well has both main wellbore and side-tracks slotted or perforated to allow injection and production. The branch wells can also be controlled to maintain conformance. The pump in this case is preferably sumped as illustrated in the previous Figs.
[0142] In one variant, when appropriate the infill well could have regularly spaced branches extending close enough to the SAGD well pairs to encourage growth of a "fingered" steam zone away from the SAGD well pairs. The branches may be provided to target vertically unbroken zones and zones at the toe end of the SAGD well pairs.
[0143] Referring to Figs 9-11, which are seismic images, the warmer colours (yellow, red) represent presence of steam and thus a hump zone 26 below, what could be referred to as an "anomaly" here, and the blues represent absence of steam and thus a vertically unbroken zone 24. The proposed infill well 30 lies closer to one SAGD well pair than the other (plan view), and passes below a roughly elliptical "hole"
representing where steam has not formed a combined steam region (plan view again). For Figs and 11, note that "Devonian" unconformity is the interface between sand and carbonate rock. The parallel and perpendicular views clearly show that the steam chamber is not connected everywhere above the infill well.
[0144] Some aspects and embodiments of the present invention have the following features or characteristics:
¨ Time-lapse (4D) seismic enables for later optimization steps depending on oil distribution.
¨ A downhole pump located low in the reservoir enables to drain low-lying reservoir.
¨ Inflow control enables to retain good conformance as oil in the inflow region is depleted and the overlying steam zone changes with time.
¨ Depending on the configuration of infill oil (e.g. low "pockets" in the reservoir base), sidetrack wells will be helpful in maximizing recovery.
¨ Time-lapse seismic surveys are conducted periodically ¨ typically once per year ¨ and well control is tuned based on new oil distribution..
, ¨ Seismic data interpretations are used to characterize the target oil accumulation and calibrate numerical simulation models ¨ Numerical models are used to develop a performance expectation for the infill resource.
¨ Infill well is drilled and concurrently appraised with appropriate logging while drilling technology then completed using adaptive completion technology in one of the configurations depicted, or combinations or variations thereof ¨ Steam is injected if required ¨ perhaps alternating with periods of oil production-to enhance infill oil mobility ¨ Once continuity with the SAGD chambers is established wells are operated to maximize recovery by gravity drainage ¨ Optionally: If downhole flow meters are incorporated (nearly commercial at present), the inflow is adjusted more frequently to maintain uniform production along the well ¨ Embodiments tune the design of the infill well based on the observable distribution of oil in the target region and allows the flow performance of the well to be repeatedly optimized over the life of the infill well.
¨ Improvement over conventional practices which undoubtedly leave significant remaining oil above the infill well due to poor conformance along the well, and considerable oil below the well due to undulating reservoir base topography.
¨ Improvement over conventional practices of infill wells that are provided approximately midway between adjacent SAGD well pairs and completed essentially at the same elevation as neighbouring SAGD producers, more-or-less horizontally oriented and with standard completions (e.g. uniform slotting or perforation along the infill well).
¨ For embodiments comprising multilateral branches, where sidetrack wells are tied to the main wellbore, it may be advantageous if the junctions are located in competent rock below the reservoir than in unconsolidated oilsands.
¨ Embodiments of the invention utilize direct observation of the target infill oil and reservoir base topography to design an optimal infill well completion. The result is faster and more complete recovery of the oil in the infill region.
¨ Thermally capable downhole flow sensors may be incorporated and used in conjunction with ICDs to optimize performance of the infill well throughout its lifetime.
[0145] It should be understood that the present invention is not limited to the embodiments or aspects described herein.
10 [0095] In some implementations, the at least one predicted boundary of the residual zone is defined by a predicted steam impingement area of the SAGD steam chamber areas.
[0096] In some implementations, the adjusting of the operation of the infill well comprises controlling inflow proximate the predicted steam impingement area.
[0097] In some implementations, the process includes adjusting downhole flow conditions using inflow control devices in accordance with recovery characteristics and/or evolution of at least one of the boundaries of the residual zone.
[0098] In some implementations, the operating of the infill well further comprises injecting steam into the infill well to enhance mobility of the hydrocarbons in the residual zone.
[0099] In some implementations, the operating of the infill well further comprises alternating between production and steam injection modes to enhance mobility of the hydrocarbons in the residual zone.
[0100] In some implementations, there is provided a method for recovering heavy hydrocarbons from an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas, the method comprising:
operating an infill well positioned in the three-dimensional residual zone defined by boundaries that vary along a length dimension of the residual zone, wherein the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas; and flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chamber areas defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication; and at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas;
wherein the infill well comprises a completion in the at least one hump zone configured to avoid steam breakthrough into the infill well; and wherein the operating comprises producing heavy hydrocarbons from the infill well.
[0101] In some implementations, there is provided a method for providing an infill well in an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas for recovery of heavy hydrocarbons, the method comprising:
drilling an infill bore in the residual zone along a trajectory based on boundaries of the residual zone, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
wherein the drilling comprises:
drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores extending from the main bore into the residual zone;
completing an infill well in the infill bore;
wherein the infill well is configured to recover heavy hydrocarbons from the residual zone.
[0102] In some implementations, the process includes drilling the multilateral branch bores at regularly spaced intervals.
[0103] In some implementations, the process includes drilling the multilateral branch bores so as to be spaced away from the SAGD steam chamber areas by an offset distance selected so as to be sufficient in order to avoid steam breakthrough through the multilateral branch bores.
[0104] In some implementations, the offset distance is substantially the same for each of the multilateral branch bores.
[0105] In some implementations, the offset distance is sufficient in order to allow encouragement of steam growth from the SAGD steam chamber areas toward the multilateral branch bores when the infill well is operated.
[0106] In some implementations, the process includes drilling the multilateral branch bores at a toe end of the residual zone.
[0107] In some implementations, the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication; and at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas; and wherein the method further comprises drilling the multilateral branch bores to extend into the vertically unbroken residual zone.
[0108] In some implementations, completing the infill well comprises completing a main well in the main bore; and completing branch side wells in the multilateral branch bores.
[0109] In some implementations, the branch side wells are configured to encourage growth of steam fingers from the SAGD steam chamber areas toward the branch side wells.
[0110] In some implementations, the branch side wells are configured to avoid steam breakthrough from the SAGD steam chamber areas.
[0111] In some implementations, the branch side wells comprise a liner. In some implementations, the liner is slotted or perforated. In some implementations, the liner comprises perforations of varied size or frequency.
[0112] In some implementations, the branch side wells comprise a blank liner section.
[0113] In some implementations, the blank liner section is provided proximate to a boundary defined by one of the SAGD steam chamber areas.
[0114] In some implementations, the branch side wells are at an oblique angle with respect to the main well.
[0115] In some implementations, the branch side well sections extend obliquely toward a toe end of the residual zone.
[0116] In some implementations, the branch side wells comprise completions allowing injection and production.
[0117] In some implementations, the branch side wells extend to recover lows or oil accumulations in the residual zone.
[0118] In some implementations, the process includes controlling the branch side wells with inflow control devices.
[0119] In some implementations, the drilling of the infill well comprises drilling junctions of the multilateral branch bores and the main horizontal bore in competent rock below the reservoir.
BRIEF DESCRIPTION OF THE DRAWINGS
[0120] Figs la-le are plan view schematics of single SAGD well pairs with steam chambers in dotted lines.
[0121] Figs 2a-2b are lateral cross-sectional view schematics of SAGD well pairs with steam chambers in dotted lines.
[0122] Figs 3a-3b are perspective view schematics of sections of residual zones formed between neighbouring SAGD well pairs.
[0123] Fig 4a-4e are perspective view schematics of different types of residual zones formed between neighbouring SAGD well pairs.
[0124] Fig 5 is a longitudinal cross-sectional view schematic, with vertical dimension exaggerated, of an infill well with a downhole sumped pump.
[0125] Fig 6 is a longitudinal cross-sectional view schematic, with vertical dimension exaggerated, of an infill well with a blank liner proximate a steam chamber boundary.
[0126] Fig 7 is a perspective isolation view schematic of neighbouring SAGD
well pairs and an in-between infill well with a main section and branched side sections.
[0127] Fig 8 is a block diagram flow chart.
[0128] Fig 9 is a seismic plan view image representing a residual zone in between neighbouring SAGD well pairs and an infill well. The warmer colours represent the presence of steam, while the "anomaly" in blue is a vertically unbroken zone.
[0129] Fig 10 is a seismic longitudinal cross-sectional image from line X.
10 [0130] Fig 11 is a seismic lateral cross-sectional image along line Xl.
DETAILED DESCRIPTION
[0131] The infill completion methods of the present invention allow improved conformance to complex infill lithology, base topography and neighbouring steam chamber boundaries in an accurate and adaptive manner.
[0132] Unlike prior techniques, which understate or overlook the complex three-dimensional and constantly evolving nature of SAGD residual zones for infill opportunities, the methods of the present invention take into account the three-dimensional boundaries of such residual zones.
[0133] Referring to Figs la-le, a given SAGD well pair 20 can generate a variety of 20 steam chambers 22 or mobilised hydrocarbon zones, with different plan view shapes and orientations.
[0134] Referring to Figs 2a-2b, when two SAGD well pairs 20 are located beside each other, their steam chambers 22 usually grow upward and outward. Depending on their separation distance, the operation of the SAGD well pairs and the lithology of the formation, the steam chambers 22 can remain separate as shown in Fig 2a or they may join together form a common steam chamber as shown in Fig 2b.
[0135] Referring now to Fig 3a, when the steam chambers remain separate, the resulting residual zone may be referred to as a "vertically unbroken zone" 24.
This type of zone often has an elongated shape with an overlying boundary following the overburden, an underlying boundary following the underburden topology and flanking boundaries which are often concave defined by the adjacent steam chambers.
[0136] Referring to Fig 3b, when the steam chambers of neighbouring SAGD well pairs coalesce to form a common steam chamber, the resulting residual zone may be referred to as a "hump zone" 26. This type of zone often has an elongated shape with an underlying boundary following the underburden topology, while the overlying and flanking boundaries are both defined by the common steam chamber.
[0137] Referring now to Figs 4a-4e, various combinations of hump zones 26 and vertically unbroken zones 24 can co-exist along a single infill residual zone 30. Each of these scenarios calls for a corresponding adapted infill well.
[0138] Referring to Figs 5-7, a horizontal infill well 31 is provided in the residual zone 30.
[0139] Referring to Fig 5, there may be provided a low point in the infill well trajectory in the underburden 32. A downhole pump 34 may be sited at the low point. The infill well 31 is completed in reservoir, e.g. with a slotted liner 36. The infill well 30 may be provided approximately parallel to and midway between the neighbouring SAGD
well pairs, depending on steam configuration. The downhole pump and well trajectory are preferably adapted to the baseline topology.
[0140] Referring to Fig 6, which shows a similar strategy to that of Fig 5, the completion include a liner with a blank section 38 proximate to the steam chamber boundary. It should be understood that the steam chamber boundary may be determined by seismic surveying, preferably using a time-lapse seismic method which can allow a predicted steam chamber boundary and thus foresee certain problematic locations along the infill well. Depending on the timing of the seismic surveying (before or after drilling, completion or operation), the infill well can be adapted accordingly.
[0141] Referring to Fig 7, the infill well may include a main section 40 and multilateral branch sections 42,44. The multilateral branches target reservoir lows and oil accumulations, for example. The infill well has both main wellbore and side-tracks slotted or perforated to allow injection and production. The branch wells can also be controlled to maintain conformance. The pump in this case is preferably sumped as illustrated in the previous Figs.
[0142] In one variant, when appropriate the infill well could have regularly spaced branches extending close enough to the SAGD well pairs to encourage growth of a "fingered" steam zone away from the SAGD well pairs. The branches may be provided to target vertically unbroken zones and zones at the toe end of the SAGD well pairs.
[0143] Referring to Figs 9-11, which are seismic images, the warmer colours (yellow, red) represent presence of steam and thus a hump zone 26 below, what could be referred to as an "anomaly" here, and the blues represent absence of steam and thus a vertically unbroken zone 24. The proposed infill well 30 lies closer to one SAGD well pair than the other (plan view), and passes below a roughly elliptical "hole"
representing where steam has not formed a combined steam region (plan view again). For Figs and 11, note that "Devonian" unconformity is the interface between sand and carbonate rock. The parallel and perpendicular views clearly show that the steam chamber is not connected everywhere above the infill well.
[0144] Some aspects and embodiments of the present invention have the following features or characteristics:
¨ Time-lapse (4D) seismic enables for later optimization steps depending on oil distribution.
¨ A downhole pump located low in the reservoir enables to drain low-lying reservoir.
¨ Inflow control enables to retain good conformance as oil in the inflow region is depleted and the overlying steam zone changes with time.
¨ Depending on the configuration of infill oil (e.g. low "pockets" in the reservoir base), sidetrack wells will be helpful in maximizing recovery.
¨ Time-lapse seismic surveys are conducted periodically ¨ typically once per year ¨ and well control is tuned based on new oil distribution..
, ¨ Seismic data interpretations are used to characterize the target oil accumulation and calibrate numerical simulation models ¨ Numerical models are used to develop a performance expectation for the infill resource.
¨ Infill well is drilled and concurrently appraised with appropriate logging while drilling technology then completed using adaptive completion technology in one of the configurations depicted, or combinations or variations thereof ¨ Steam is injected if required ¨ perhaps alternating with periods of oil production-to enhance infill oil mobility ¨ Once continuity with the SAGD chambers is established wells are operated to maximize recovery by gravity drainage ¨ Optionally: If downhole flow meters are incorporated (nearly commercial at present), the inflow is adjusted more frequently to maintain uniform production along the well ¨ Embodiments tune the design of the infill well based on the observable distribution of oil in the target region and allows the flow performance of the well to be repeatedly optimized over the life of the infill well.
¨ Improvement over conventional practices which undoubtedly leave significant remaining oil above the infill well due to poor conformance along the well, and considerable oil below the well due to undulating reservoir base topography.
¨ Improvement over conventional practices of infill wells that are provided approximately midway between adjacent SAGD well pairs and completed essentially at the same elevation as neighbouring SAGD producers, more-or-less horizontally oriented and with standard completions (e.g. uniform slotting or perforation along the infill well).
¨ For embodiments comprising multilateral branches, where sidetrack wells are tied to the main wellbore, it may be advantageous if the junctions are located in competent rock below the reservoir than in unconsolidated oilsands.
¨ Embodiments of the invention utilize direct observation of the target infill oil and reservoir base topography to design an optimal infill well completion. The result is faster and more complete recovery of the oil in the infill region.
¨ Thermally capable downhole flow sensors may be incorporated and used in conjunction with ICDs to optimize performance of the infill well throughout its lifetime.
[0145] It should be understood that the present invention is not limited to the embodiments or aspects described herein.
Claims (97)
1. A method for providing a generally horizontal infill well in an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas for recovery of heavy hydrocarbons, the method comprising:
determining boundaries of the residual zone, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
drilling an infill bore in the residual zone along a trajectory determined based on the boundaries; and completing an infill well in the infill bore; and wherein the infill well is configured to recover heavy hydrocarbons from the residual zone.
determining boundaries of the residual zone, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
drilling an infill bore in the residual zone along a trajectory determined based on the boundaries; and completing an infill well in the infill bore; and wherein the infill well is configured to recover heavy hydrocarbons from the residual zone.
2. The method of claim 1, wherein the infill well is further configured such that heat provided by the two SAGD chamber areas facilitates the recovery of heavy hydrocarbons.
3. The method of claim 1, wherein the step of determining boundaries of the residual zone comprises:
performing four-dimensional seismic surveillance of the residual zone.
performing four-dimensional seismic surveillance of the residual zone.
4. The method of claim 1, 2 or 3, further comprising:
for at least one boundary of the residual zone, predetermining an offset distance between the boundary and the infill well; and determining the trajectory of the infill bore to be spaced away from each of the at least one boundary by at least the corresponding offset distance.
for at least one boundary of the residual zone, predetermining an offset distance between the boundary and the infill well; and determining the trajectory of the infill bore to be spaced away from each of the at least one boundary by at least the corresponding offset distance.
5. The method of claim 4, wherein at least one boundary for which an offset distance is determined is defined by the SAGD steam chamber areas.
6. The method of claim 5, wherein predetermining the offset distance comprises selecting a distance that is sufficient in order to avoid steam breakthrough from one of the SAGD steam chamber areas into the infill bore.
7. The method of claim 5 or 6, wherein predetermining the offset distance comprises selecting a distance that is sufficient in order to encourage steam to grow from one of the SAGD steam chamber areas toward the infill well.
8. The method of any one of claims 4 to 7, comprising:
identifying a latent steam breakthrough location from one of the SAGD steam chamber areas into the infill well.
identifying a latent steam breakthrough location from one of the SAGD steam chamber areas into the infill well.
9. The method of claim 8, wherein the completing of the infill well further comprises:
providing reduced inflow completion proximate the latent steam breakthrough location.
providing reduced inflow completion proximate the latent steam breakthrough location.
10. The method of claim 9, wherein the reduced inflow completion comprises blank liners.
11. The method of claim 9 or 10, wherein the reduced inflow completion comprises liners comprising reduced size perforations or reduced size slots.
12. The method of any one of claims 1 to 11, wherein the step of drilling the infill bore comprises:
providing a low-lying sump bore section positioned below an underlying boundary of the residual zone.
providing a low-lying sump bore section positioned below an underlying boundary of the residual zone.
13. The method of claim 12, wherein the underlying boundary comprises underburden between heels of SAGD well pairs.
14. The method of claim 12 or 13, wherein the step of completing the infill well further comprises providing a downhole element located in the low-lying bore section.
15. The method of any one of claims 12 to 14, wherein the step of drilling the infill bore further comprises:
an upper bore section communicating with the low-lying sump bore section and extending above and along the underlying boundary toward toes of the SAGD
well pairs.
an upper bore section communicating with the low-lying sump bore section and extending above and along the underlying boundary toward toes of the SAGD
well pairs.
16. The method of claim 15, wherein the step of completing the infill well further comprises providing a production liner section located in the upper bore section.
17. The method of claim 16, wherein the production liner comprises a slotted liner.
18. The method of claim 1 or 2, wherein the drilling of the infill bore comprises:
determining the trajectory so as to be spaced away from the flanking boundaries defined by the SAGD steam chamber areas, by an offset distance that is substantially the same on either side of the trajectory.
determining the trajectory so as to be spaced away from the flanking boundaries defined by the SAGD steam chamber areas, by an offset distance that is substantially the same on either side of the trajectory.
19. The method according to claim 18, wherein the offset distance is selected in order to be sufficient to avoid steam breakthrough from the SAGD steam chamber areas into the infill well.
20. The method of any one of claims 1 to 19, wherein the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication.
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication.
21. The method of any one of claims 1 to 20, wherein the residual zone comprises:
at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas.
at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas.
22. The method of any one of claims 1 to 21, wherein:
drilling the infill bore comprises:
drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores.
drilling the infill bore comprises:
drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores.
23. The method of claim 22, comprising drilling the multilateral branch bores at regularly spaced intervals.
24. The method of claim 22 or 23, comprising drilling the multilateral branch bores so as to be spaced away from the SAGD steam chamber areas by an offset distance selected in order to be sufficient to avoid steam breakthrough from the SAGD
steam chamber areas into the infill well.
steam chamber areas into the infill well.
25. The method of any one of claims 22 to 24, comprising drilling the multilateral branch bores at a toe end of the residual zone.
26. The method of claim 21, wherein:
drilling the infill bore comprises:
drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores in the vertically unbroken residual zone.
drilling the infill bore comprises:
drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores in the vertically unbroken residual zone.
27. The method of any one of claims 22 to 26, wherein:
completing the infill well comprises:
completing a main well in the main bore; and completing branch side wells in the branch bores.
completing the infill well comprises:
completing a main well in the main bore; and completing branch side wells in the branch bores.
28. The method of claim 27, wherein the branch side wells are configured to encourage growth of steam fingers from the SAGD steam chamber areas.
29. The method of claim 27 or 28, wherein the branch side wells are configured to avoid steam breakthrough from the SAGD steam chamber areas into the branch side wells.
30. The method of any one of claims 27 to 29, wherein completing the infill well comprises:
providing the branch side wells with a liner.
providing the branch side wells with a liner.
31. The method according to claim 30, wherein the liner is slotted or perforated.
32. method of claim 31, wherein liner comprises slots or perforations of varied size or frequency.
33. The method of any one of claims 1 to 32, wherein completing the infill well comprises:
providing the infill well with a blank liner section.
providing the infill well with a blank liner section.
34. The method of claim 33, wherein the blank liner section is provided proximate to a boundary defined by one of the SAGD steam chamber areas.
35. The method of any one of claims 1 to 34, wherein determining boundaries of the residual zone comprises:
time-lapse monitoring of the residual zone to determine the evolution of at least one of the boundaries;
determining at least one predicted boundary for a stage of the drilling of the infill well and/or the completing of the infill well.
time-lapse monitoring of the residual zone to determine the evolution of at least one of the boundaries;
determining at least one predicted boundary for a stage of the drilling of the infill well and/or the completing of the infill well.
36. The method of claim 35, comprising adjusting the drilling of the infill well and/or the completing of the infill well according to the at least one predicted boundary of the residual zone.
37. The method of claim 36, wherein the at least one predicted boundary of the residual zone is defined by the SAGD steam chamber areas and further defined by a predicted steam impingement area within at least one of the SAGD chamber areas, and the adjusting is performed to provide sufficient offset distance between the infill bore and/or the infill well from the predicted steam impingement area to avoid steam breakthrough into the infill bore and/or the infill well.
38. The method of claim 36 or 37, wherein the adjusting of the completion of the infill well comprises:
providing the infill well with an inflow control device proximate the predicted steam impingement area.
providing the infill well with an inflow control device proximate the predicted steam impingement area.
39. The method of claim 38, further comprising:
recovering the heavy hydrocarbons through the infill well in production mode, monitoring recovery characteristics of the infill well and/or evolution of at least one of the boundaries of the residual zone; and adjusting downhole flow conditions using the inflow control devices in accordance with the recovery characteristics and/or the evolution of at least one of the boundaries of the residual zone.
recovering the heavy hydrocarbons through the infill well in production mode, monitoring recovery characteristics of the infill well and/or evolution of at least one of the boundaries of the residual zone; and adjusting downhole flow conditions using the inflow control devices in accordance with the recovery characteristics and/or the evolution of at least one of the boundaries of the residual zone.
40. The method of any one of claims 1 to 39, wherein the step of drilling the infill bore comprises adapting the trajectory according to baseline topology of the underlying boundary.
41. The method of claim 38, wherein the baseline topology of the underlying boundary is undulating.
42. The method of any one of claims 1 to 39, wherein the drilling of the infill bore is adjusted based on azimuthal resistivity.
43. The method of any one of claims 1 to 40, wherein the drilling of the infill bore is adjusted based on density measurements.
44. A method for recovering heavy hydrocarbons from an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas, the method comprising:
operating an infill well positioned in the residual zone along a trajectory based on determined boundaries, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
wherein the operating comprises producing heavy hydrocarbons from the infill well to recover heavy hydrocarbons from the residual zone.
operating an infill well positioned in the residual zone along a trajectory based on determined boundaries, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
wherein the operating comprises producing heavy hydrocarbons from the infill well to recover heavy hydrocarbons from the residual zone.
45. The method of claim 44, wherein the infill well bore comprises:
a low-lying sump bore section positioned below an underlying boundary of the residual zone, wherein the underlying boundary comprises underburden between heels of SAGD well pairs.
a low-lying sump bore section positioned below an underlying boundary of the residual zone, wherein the underlying boundary comprises underburden between heels of SAGD well pairs.
46. The method of claim 45, wherein the infill well comprises a downhole pump element that is located in the low-lying bore section.
47. The method of claim 45 or 46, wherein the infill well bore further comprises:
an upper bore section communicating with the low-lying sump bore section and extending above and along the underlying boundary toward toes of the SAGD
well pairs.
an upper bore section communicating with the low-lying sump bore section and extending above and along the underlying boundary toward toes of the SAGD
well pairs.
48. The method of claim 47, wherein the infill well comprises a production liner section that is located in the upper bore section.
49. The method of any one of claims 44 to 48, wherein the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication.
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication.
50. The method of any one of claims 44 to 48, wherein the residual zone comprises:
at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas.
at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas.
51. The method of any one of claims 44 to 50, wherein the trajectory of the infill well is located with at least one offset distance from at least one of the boundaries of the residual zone defined by the SAGD steam chamber areas, the at least one offset distance being sufficient in order to avoid steam breakthrough from one of the SAGD
steam chamber areas into the infill well.
steam chamber areas into the infill well.
52. The method of claim 51, wherein the at least one offset distance is sufficient in order to encourage steam to grow from one of the SAGD steam chamber areas toward the infill well
53. The method of any one of claim 44 to 52, wherein the infill well comprises reduced inflow completion proximate a latent steam breakthrough location from one of the SAGD steam chamber areas into the infill well.
54. The method of claim 53, wherein the reduced inflow completion comprises blank liners.
55. The method of claim 53 or 54, wherein the reduced inflow completion comprises liners comprising reduced size perforations or reduced size slots.
56. The method of any one of claims 44 to 55, wherein the trajectory of the infill well is spaced away from the flanking boundaries defined by the SAGD steam chamber areas by an offset distance that is substantially the same on either side of the trajectory.
57. The method according to claim 56, wherein the offset distance is selected in order to be sufficient to avoid steam breakthrough from the SAGD steam chamber areas into the infill well.
58. The method of any one of claims 44 to 57, wherein the infill well comprises:
a horizontal main well along the length of the residual zone; and multilateral branch wells extending from the main well into the residual zone.
a horizontal main well along the length of the residual zone; and multilateral branch wells extending from the main well into the residual zone.
59. The method of claim 58, wherein the multilateral branch wells are provided at regularly spaced intervals.
60. The method of claim 58 or 59, wherein the multilateral branch wells extend at an offset distance with respect to the SAGD steam chamber areas selected to be sufficient in order to avoid steam breakthrough from the SAGD steam chamber areas into the infill well.
61. The method of any one of claims 58 to 60, wherein the multilateral branch wells are located at a toe end of the residual zone.
62. The method of anyone of claims 58 to 61, wherein the multilateral branch wells are located in a vertically unbroken residual zone.
63. The method of any one of claims 58 to 62, wherein the multilateral branch wells are configured to encourage growth of steam fingers from the SAGD steam chamber areas.
64. The method of any one of claims 58 to 63, wherein the multilateral branch wells are configured to avoid steam breakthrough from the SAGD steam chamber areas into the multilateral branch wells.
65. The method of any one of claims 58 to 64, wherein the multilateral branch wells comprise a liner.
66. The method of claim 65, wherein the liner is slotted or perforated.
67. The method of claim 66, wherein the liner comprises perforations of varied size or frequency.
68. The method of any one of claims 65 to 67, wherein the multilateral branch wells comprise a blank liner section.
69. The method of claim 68, wherein the blank liner section is provided proximate to a boundary defined by one of the SAGD steam chamber areas.
70. The method of any one of claims 44 to 69, comprising adjusting the operation of the infill well according to at least one predicted boundary of the residual zone, the at least one predicted boundary being determined by time-lapse monitoring of the residual zone.
71. The method of claim 70, wherein the at least one predicted boundary of the residual zone is defined by a predicted steam impingement area of the SAGD steam chamber areas.
72. The method of claim 71, wherein the adjusting of the operation of the infill well comprises:
controlling inflow proximate the predicted steam impingement area.
controlling inflow proximate the predicted steam impingement area.
73. The method of any one of claims 44 to 72, further comprising:
adjusting downhole flow conditions using inflow control devices in accordance with recovery characteristics and/or evolution of at least one of the boundaries of the residual zone.
adjusting downhole flow conditions using inflow control devices in accordance with recovery characteristics and/or evolution of at least one of the boundaries of the residual zone.
74. The method of any one of claims 44 to 73, wherein the operating of the infill well further comprises:
injecting steam into the infill well to enhance mobility of the hydrocarbons in the residual zone.
injecting steam into the infill well to enhance mobility of the hydrocarbons in the residual zone.
75. The method of any one of claims 44 to 74, wherein the operating of the infill well further comprises:
alternating between production and steam injection modes to enhance mobility of the hydrocarbons in the residual zone.
alternating between production and steam injection modes to enhance mobility of the hydrocarbons in the residual zone.
76. A method for recovering heavy hydrocarbons from an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas, the method comprising:
operating an infill well positioned in the three-dimensional residual zone defined by boundaries that vary along a length dimension of the residual zone, wherein the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas; and flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chamber areas defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication; and at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas;
wherein the infill well comprises a completion in the at least one hump zone configured to avoid steam breakthrough into the infill well; and wherein the operating comprises producing heavy hydrocarbons from the infill well.
operating an infill well positioned in the three-dimensional residual zone defined by boundaries that vary along a length dimension of the residual zone, wherein the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas; and flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chamber areas defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication; and at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir;
and opposed flanking steam boundaries defined by the SAGD steam chamber areas;
wherein the infill well comprises a completion in the at least one hump zone configured to avoid steam breakthrough into the infill well; and wherein the operating comprises producing heavy hydrocarbons from the infill well.
77. A method for providing an infill well in an elongated three-dimensional residual zone defined between two Steam Assisted Gravity Drainage (SAGD) steam chamber areas for recovery of heavy hydrocarbons, the method comprising:
drilling an infill bore in the residual zone along a trajectory based on boundaries of the residual zone, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
wherein the drilling comprises:
drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores extending from the main bore into the residual zone;
completing an infill well in the infill bore;
wherein the infill well is configured to recover heavy hydrocarbons from the residual zone.
drilling an infill bore in the residual zone along a trajectory based on boundaries of the residual zone, wherein the boundaries:
vary along a length dimension of the three-dimensional residual zone;
include one or more of: an overlying boundary, an underlying boundary, a flanking boundary and an internal lithological boundary; and include at least one boundary defined by the SAGD steam chamber areas;
wherein the drilling comprises:
drilling a horizontal main bore along the length of the residual zone; and drilling multilateral branch bores extending from the main bore into the residual zone;
completing an infill well in the infill bore;
wherein the infill well is configured to recover heavy hydrocarbons from the residual zone.
78. The method of claim 77, comprising drilling the multilateral branch bores at regularly spaced intervals.
79. The method of claim 77 or 78, comprising drilling the multilateral branch bores so as to be spaced away from the SAGD steam chamber areas by an offset distance selected so as to be sufficient in order to avoid steam breakthrough through the multilateral branch bores.
80. The method of claim 79, wherein the offset distance is substantially the same for each of the multilateral branch bores.
81. The method of claim 79 or 80, wherein the offset distance is sufficient in order to allow encouragement of steam growth from the SAGD steam chamber areas toward the multilateral branch bores when the infill well is operated.
82. The method of any one of claims 77 or 81, comprising drilling the multilateral branch bores at a toe end of the residual zone.
83. The method of any one of claims 77 to 82, wherein the residual zone comprises:
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication; and at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas; and wherein the method further comprises drilling the multilateral branch bores to extend into the vertically unbroken residual zone.
at least one hump zone extending part of the length of the residual zone, each hump zone being defined by:
an overlying steam boundary defined by the SAGD steam chamber areas;
and flanking steam boundaries defined by the SAGD steam chamber areas, wherein the SAGD steam chambers defining the overlying steam boundary and the opposed flanking steam boundaries are in fluid communication; and at least one vertically unbroken zone extending part of the length of the residual zone, each vertically unbroken zone being defined by:
an overlying reservoir boundary defined by part of the reservoir; and opposed flanking steam boundaries defined by the SAGD steam chamber areas; and wherein the method further comprises drilling the multilateral branch bores to extend into the vertically unbroken residual zone.
84. The method of any one of claims 77 to 83, wherein completing the infill well comprises:
completing a main well in the main bore; and completing branch side wells in the multilateral branch bores.
completing a main well in the main bore; and completing branch side wells in the multilateral branch bores.
85 The method of claim 84, wherein the branch side wells are configured to encourage growth of steam fingers from the SAGD steam chamber areas toward the branch side wells.
86. The method of claim 84 or 85, wherein the branch side wells are configured to avoid steam breakthrough from the SAGD steam chamber areas
87. The method of any one of claims 84 to 86, wherein the branch side wells comprise a liner.
88. The method of claim 87, wherein the liner is slotted or perforated.
89. The method of claim 87 or 88, wherein the liner comprises perforations of varied size or frequency.
90. The method of any one of claims 87 to 89, wherein the branch side wells comprise a blank liner section.
91. The method of claim 90, wherein the blank liner section is provided proximate to a boundary defined by one of the SAGD steam chamber areas.
92. The method of any one of claims 84 to 91, wherein the branch side wells are at an oblique angle with respect to the main well.
93. The method of claim 92, wherein the branch side well sections extend obliquely toward a toe end of the residual zone.
94. The method of any one of claims 84 to 93, wherein the branch side wells comprise completions allowing injection and production.
95. The method of any one of claims 84 to 94, wherein the branch side wells extend to recover lows or oil accumulations in the residual zone.
96. The method of any one of claims 84 to 95, further comprising controlling the branch side wells with inflow control devices.
97. The method of any one of claims 77 to 96, wherein the drilling of the infill well comprises drilling junctions of the multilateral branch bores and the main horizontal bore in competent rock below the reservoir.
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| CA2684049A CA2684049C (en) | 2009-10-27 | 2009-10-27 | Infill well methods for sagd well heavy hydrocarbon recovery operations |
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| CA2684049A CA2684049C (en) | 2009-10-27 | 2009-10-27 | Infill well methods for sagd well heavy hydrocarbon recovery operations |
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| CA2780670C (en) | 2012-06-22 | 2017-10-31 | Imperial Oil Resources Limited | Improving recovery from a subsurface hydrocarbon reservoir |
| US9587480B2 (en) | 2013-03-14 | 2017-03-07 | Suncor Energy Inc. | Cellar oil recovery techniques for in situ operations |
| CA2913130C (en) | 2013-05-22 | 2021-01-12 | Total E&P Canada, Ltd. | Fishbone sagd |
| WO2015054267A2 (en) * | 2013-10-07 | 2015-04-16 | Bp Corporation North America Inc. | Systems and methods for enhancing steam distribution and production in sagd operations |
| US10385666B2 (en) | 2014-01-13 | 2019-08-20 | Conocophillips Company | Oil recovery with fishbone wells and steam |
| CA2943134C (en) | 2015-09-23 | 2022-03-08 | Conocophilips Company | Thermal conditioning of fishbones |
| US11306570B2 (en) | 2017-06-22 | 2022-04-19 | Conocophillips Company | Fishbones, electric heaters and proppant to produce oil |
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