Downhole equipment, tools and assembly procedures for the drilling, tie-in and completion of vertical cased oil wells connected to liner-equipped multiple drainholes

Apparatus for completing a multi-branch cased well for oil recovery by sequential cyclic steam injection methods and for petroleum production from non-uniformly-pressured heterogeneous reservoirs through medium curvature, liner equipped, horizontal drainholes;

• said apparatus includes downhole equipment, tools and devices for making casing/liner and liner/tubing sealed connections and individual liner/drainhole flow connections, comprising:
• a) a special steel cylindrical casing joint presenting an elliptical side window machined at a prescribed small downwards kick-off angle and covered by a drillable metal plate shaped to conform with the outer surface of said casing joint which is also equipped with a drillable orientation device comprising a vertical key or groove,
• b) a drillable support and packer affixed in said casing joint by slips below said window,
• c) a retrievable single-channel whipstock tool set within said packer in accordance with a matching orientation device;
• said whipstock presents at least one guiding groove on its slanted surface and at least one latching recess on its cylindrical surface,
• d) a short intermediate steel liner of a diameter slightly smaller than said window's short axis, allowing its insertion into a kicked-off hole, through the window and wherein the upper end of said intermediate liner is equipped with a pressure-sealing gasketed drillable collar shaped to conform both with the inner surface of the casing joint along the edge of the window and with said guiding groove in the whipstock, so that said gasketed end, when pressed against the inner surface of the casing joint, provides a permanent high-temperature seal in addition to thermal cement around said intermediate liner,
• e) an overshot tool, equipped internally with at least one spring-loaded hook to latch into the whipstock's latching recess or key and pull it out;
• said tool also presents at its lower end some milling cutters, for surfacing the liner's drillable collar and for drilling-out the packer slips and support, and said tool includes a latching device, for pulling-out the drilled-out packer,
• f) a selectively perforated drainhole steel liner inserted in a drainhole drilled through such intermediate liner, hung from above as well as from below and cemented in the lower part of said intermediate liner, and having the annular space between intermediate liner and drainhole liner sealed with an inflatable packer,
• g) a tubing completion assembly conveying production fluids from a drainhole to the surface and steam from the surface to a drainhole, wherein said tubing completion is terminated at its lower end by a heat-resistant, pressure-tight, multiple-breakable-sealed connecting device wherein several articulated connector steel tubes are each inserted into the upper part of the intermediate liner of a drainhole, and the annular space between the inner surface of said intermediate liner and said connector tube is sealced by an inflatable thermal packer,
• h) a hydraulically-operated slot-cutting tool for selectively perforating the uncemented lower part of each drainhole liner.

Apparatus for completing a multi-branch cased well for oil recovery by sequential cyclic steam injection methods and for petroleum products from non-uniformly-pressured heterogeneous reservoirs through medium curvature, liner-equipped, horizontal drainholes;

• said apparatus includes downhole equipment, tool and devices for making multiple casing/liner and liner/tubing sealed connections and individual liner/drainhole flow connections, comprising:
• at least one special casing joint in the casing string of a vertical hole, opposite a reamed interval straddling the kick-off points of one or more drainholes, said joint presenting one or more elliptical windows oriented downwards and facing pre-selected kick-off directions at various depths,
• b) a telescopic steel liner stub closed at its lower end by a drillable metal plate plugging each window, and machined at both ends to conform respectively with the outer surface of the casing window for the lower end and with the inner surface of the casing window for the upper end,
• c) two drillable metal guide cages supporting said stub, inclined at the kick-off angle, with one of the two guide cages affixed inside the casting joint by drillable fasteners while the other, freely inserted into the stub, is mobile and can slide within said fixed guide over an interval equal to a fraction of the sub length,
• d) a drillable gasketed collar affixed to the stub's upper end to prevent said telescopic stub's upper end from popping out through the window into the reamed cavity when the stub is extended by increasing the hydraulic pressure in the casing with respect to that of the annulus during cementation of the casing string and of each extended stub, with a cement slurry displaced behind the casing and wherein said gasketed collar presents at least one guiding key or groove sliding along a bar of the fixed guide cage, to prevent any rotation of the stub around its axis,
• e) a steel liner inserted in a drainhole drilled through such a liner stub, permanently hung by a dual hanger's opposing slips into said stub and sealed with a high-temperature pressure-sealing device, in addition to thermal cement,
• f) a tubing completion assembly, conveying production fluids from a drainhole to the surface and steam from the surface to a drainhole, having at its lower end a heat-resistant, pressure-tight, multiple-breakable-sealed connecting device wherein telescopic connector steel tubes inclined at the kick-off angle are facing each window, with the tube's lower end equipped with a high-temperature sealing device insertable into the upper part of the window's stub and set when said connector tube is in its extended position, whereas the upper end of said tube is equipped with a movable sliding seal remaining within a cylindrical cavity of said tubing completion assembly,
• g) a hydraulically-operated slot-cutting tool for selectively perforating the uncemented lower part of each drainhole liner.

A method for drilling and completing a multi-branch cased well for oil recovery by sequential cyclic steam injection methods and for petroleum production from non-uniformly pressured heterogeneous reservoirs through medium-curvature, liner-equipped, horizontal drainholes, wherein casing/liner connections are permanently-sealed, wherein liner/tubing are connected by breakable-seals, and comprises the following steps:

• a) drilling a pair of short deviated boreholes through the bottom of said vertical well casing,
• b) inserting in said pair of drainholes two short intermediate steel liners using a work string ended with an inverted Y nipple joint, two articulated nipple joints, each one equipped with a rubber cementing seal cup, and holding said intermediate liner with a releaseable latch,
• c) stab-in cementing of said two short intermediate liners using said work string as cementing string, with sufficient overlap of a special high-temperature resin cement in the casing to provide a permanent gas-tight thermal tie-in of the casing with each intermediate liner,
• d) drilling successively each drainhole through each intermediate liner,
• e) running a coiled-tubing steel liner through each said intermediate liner into said drilled drainhole, affixing it to the intermediate liner with a dual hanger's opposing slips and with a high-temperature pressure-sealing device prior to cementing its upper end to the intermediate liner's lower end, with a known thermal cement,
• f) connecting the upper part of each intermediate liner to the lower end of a tubing assembly equipped with a heat-resistant pressure-tight, multiple-breakable-sealed connecting device,
• g) selectively perforating the uncemented lower part of said coiled tubing liner “in situ” using a hydraulically-operated slot-cutting tool at the end of a smaller-diameter coiled-tubing run-in from the surface and inserted through said tubing assembly and intermediate liner into said drainhole liner.

A method for sealing the intersection between a primary borehole and a branch borehole comprising the steps of:

• simultaneously installing a casing and a deformable sealing apparatus at an intersection to be formed between a primary borehole and branch borehole prior to drilling of said branch borehole;
• forming an opening in said casing at the site of the intersection to be formed between said primary borehole and said branch borehole, said opening being formed in said casing prior to installation of said casing in said primary borehole;
• drilling said branch borehole;
• and
• deforming the sealing apparatus to seal the intersection between said primary borehole and said branched borehole.

A method for sealing the intersection between a primary borehole and a branch borehole comprising the steps of:

• simultaneously installing a casing and a deformable sealing apparatus at an intersection to be formed between a primary borehole and branch borehole prior to drilling of said branch borehole;
• drilling said branch borehole;
• deforming the sealing apparatus to seal the intersection between said primary borehole and said branch borehole;
• and
• installing a liner in said branch borehole.

A method for sealing the intersection between a primary borehole and a branch borehole comprising the steps of:

• simultaneously installing a casing and a deformable sealing apparatus at an intersection to be formed between a primary borehole and branch borehole prior to drilling of said branch borehole, wherein said deformable sealing apparatus comprises a collapsible/expandable assembly comprising a primary liner having an opening therethrough and a secondary liner attached to said primary liner and communicating with said opening, said secondary liner being adapted to expand angularly from said primary liner;
• placing said secondary liner in a collapsible position within said primary liner prior to positioning said deformable sealing apparatus at said intersection;
• drilling said branch borehole;
• deforming the sealing apparatus to seal the intersection between said primary borehole and said branch borehole;
• and
• expanding said secondary liner.

A method for sealing the intersection between a primary borehole and a branch borehole comprising the steps of:

• positioning a collapsible/expandable assembly of an intersection to be formed between a primary borehole and a branch borehole, said assembly including a primary liner having an opening therethrough and a secondary liner attached to said primary liner and communicating with said opening, said secondary liner being adapted to expand from said primary liner;
• placing said secondary liner in a collapsed position within said primary liner prior to positioning said collapsible/expandable assembly at said intersection;
• expanding said second liner outwardly from said primary liner when said assembly is positioned at said intersection;
• and
• delivering drilling equipment through said primary liner and said second liner and drilling said branch borehole.

A method for sealing the intersection between a primary borehole with a casing and a branch borehole comprising the step of:

• forming an opening in said casing at the site of the intersection to be formed between said primary borehole and said branch borehole, said opening being formed in said casing prior to installation of said casing in said primary borehole;
• positioning said casing and a flanged liner at the intersection to be formed between a primary borehole and a branch borehole, said flanged liner terminating at a flange;
• installing said flanged liner so that the flange is adjacent to the periphery of said opening in said casing;
• delivering a deforming tool to said flange to deform said flange and form a seal between said flange and the periphery of said opening in said casing, to seal the intersection between said primary borehole and said branch borehole;
• and,
• delivering drilling equipment through the flanged liner and drilling the branch borehole.

A method for sealing the intersection between a primary borehole and a branch borehole comprising the steps of:

• installing casing in said primary borehole at an intersection to be formed between said primary borehole aid said branch borehole, said casing having an opening and said opening being formed in said casing prior to installation of said casing in said primary borehole;
• positioning a collapsible/expandable assembly at said intersection to be formed between a primary borehole and a branch borehole, said assembly including a primary liner having an opening therethrough and a secondary liner attached to said primary liner and communicating with said opening, said secondary liner being adapted to expand from said primary liner;
• placing said secondary liner in a collapsed position within said primary liner prior to positioning said collapsible/expandable assembly at said intersection;
• and
• expanding said secondary liner outwardly from said primary liner when said assembly is positioned at said intersection.