Combined Well System and Method for Enhanced Production

This application is based on and claims priority to U.S. Provisional Patent Application No. 63/649,355, filed May 18, 2024, which is incorporated herein in its entirety by reference.

This invention relates generally to a combined well system and more particularly, but not by way of limitation, to a combined well system comprising a first wellhead and a second wellhead connected in a subterranean formation for enhanced resource production.

Across the hydrocarbon producing regions of the world, oil and gas technology has progressed from utilizing vertical wells, to more complex deviated wells, to even more complex and challenging horizontal wells. Today, in certain areas of the world where oil and gas plays are being developed, complex, lengthy horizontal multilateral well completions have allowed oil and gas to be extracted profitably. However, the success of horizontal wells has created an ever-increasing level of complexity with lateral lengths of 3.5 miles or more and complex well bore paths becoming common.

Although successful, horizontal well technology applications are plagued with challenges. First, undesirable fracture results in the toe sections of deep horizontal wells have been noted across the industry. Poor fracturing of the toe sections causes poor fracture widths, poor fracture half-lengths, poor pump velocity and poor volume of frac proppant placed in the fracture stage. The effect of poor fracturing in these toe intervals is ultimately poor production and recovery.

Another issue with horizontal wells is the size of the borehole drilled and the subsequent production casing that is set. Cost, hole size, drilling limitations, torturous hole paths, casing rigidity, fluid issues, well control issues and weight handling limitations impede the ultimate size of the casing that is installed into boreholes. The casing installed will have a defined Area Open to Flow based on the casing internal diameter. The casing and tubular internal diameters and lengths installed have consequences to pressure drawdown, friction, flow rates and recovered reserves.

Yet another issue with fractured completions is formation damage as a result of the tremendous amount of frac water, the proppant carrier proppant fluid, that is pumped into the formations. The water that is pumped into the formation can cause clays to swell, reducing permeability to oil and gas. This clay swelling causes pressure losses and reduced oil and gas flow.

Another issue occurs due to lengthy well bores. During flowing operations, pressure losses in these lengthy sections due to friction effects are present. Initially the toe sections may not contribute to its maximum production capability leading to delayed production in the toe sections until the pressure drawdown becomes conducive to allow flow. Further, low velocities in the toe sections can cause sediment settling in the casing.

Yet another issue with horizontal wells is the risk and complexity of performing traditional interventions such as wire line and coiled tubing operations. The high risk and cost usually result in proper remediation services not being performed.

Each of the above factors and more contribute to low performing toe sections of lateral wells, leaving valuable hydrocarbon resources un-produced and reducing the profitability of the overall investment.

Based on the foregoing, it is desirable to provide a combined well system which solves production problems by utilizing partitioning of a well bore to alter pressure drawdown and rate profile along the length of the well bore.

It is further desirable for the combined well system to provide two surface outlets with a full-bore loop of casing tubulars joined in the subterranean earth for passage of tools and fluids from one well bore to the other well bore.

It is further desirable to provide a method for joining of two existing well bores or an existing well bore with a new well bore.

It is further desirable to provide a method for increasing the effective casing size of one well without increasing the actual casing size. This method may provide an increase in effective Area Open to Flow allowing for accelerated and increased production, altering of pressure drawdowns and recovery of valuable hydrocarbon resources. Accelerated production rates may have a huge impact on the Return on Investment of a project.

It is further desirable to provide a method to accelerate removal of the frac water from the formation as quickly as possible in order to minimize formation damage. Minimizing formation damage will result in a lower delta pressure skin and allow more oil and gas to flow from the formation.

It is further desirable to provide a method for super lengthy lateral wells.

In general, in a first aspect, the invention relates to a combined well system which may comprise a first well and a second well. The first well may comprise a first wellhead and first casing segment, and the second well may comprise a second wellhead and second casing segment. The combined system may comprise a connector connecting the first casing segment and second casing segment in a subterranean formation. The first and second well may be lateral wells. The connector may connect the toe section of the first well with the toe section of the second well. The combined system creates an effective down hole casing internal diameter and area open to flow that is larger than one single well. The combined system may be piggable. The combined system may or may not comprise an isolation plug which may be a fixed isolation plug.

The invention may comprise a method for fracking the toe section of the first well from the second well. An isolation plug may be set in the toe section of the first well at a distance from the connector. Fracturing fluid may be pumped into the subterranean formation from the second wellhead. Simultaneously, fracturing fluid may be pumped into the subterranean formation from the first wellhead. The invention may also comprise a method of co-mingled fracturing whereby an isolation plug is not set and fracturing fluid is pumped simultaneously from both wellheads.

The invention may also comprise a method for simultaneous injection and production. An isolation plug may be set into the toe section of the first well. Fracture or injection fluid may be pumped from the second wellhead to perform fracture operations on one side of the isolation plug. On the other side of the isolation plug, production fluids may be permitted to flow towards the first wellhead. The invention may comprise a method of production for flowing both well bores simultaneously, with or without an isolation plug, to facilitate accelerated production and accelerated removal of frac water from the formation.

Another aspect of the invention may comprise a method for connecting two wells to form the combined well system. A first well and second well may be drilled to a target point, and the two wells connected. The drill assembly of the first and second wells may comprise a ranging sensor for locating a connection point.

The invention may also comprise a method of connecting a second well to an existing first well. A rat hole may be drilled at an end of the toe section of the existing well. The rat hole may be drilled at an upwardly inclined angle relative to horizontal. A spotted tracer pill may be deployed into the rat hole. The spotted tracer pill may be detected by a ranging sensor on a drilling assembly of the second well. A drill trajectory may be calculated to direct the drilling assembly to the rat hole. The drill assembly may be steered towards the rat hole. This process may occur automatically using a computer with software.

Other advantages and features will be apparent from the following description and from the claims.

The devices and methods discussed herein are merely illustrative of specific manners in which to make and use this invention and are not to be interpreted as limiting in scope.

While the devices and methods have been described with a certain degree of particularity, it is to be noted that many modifications may be made in the details of the construction and the arrangement of the devices and components without departing from the spirit and scope of this disclosure. It is understood that the devices and methods are not limited to the embodiments set forth herein for purposes of exemplification.

In general, in a first aspect, the invention relates to a combined well systemfor enhanced production. The combined systemmay comprise two or more wells. By way of example but not limitation, the combined systemmay comprise a first welland a second well. The first welland second wellmay each be a horizontal, lateral, extended reach wells, C shaped wells, U shaped wells, multilateral wells, or each well,may be a different type of well from one another. The first wellmay be an existing well or a new well build. The secondwell may be a new well build. The wells,may further be pad or non-pad wells. Additionally, the wells,may be drilled at any angle in relation to the surface, further described below.

As shown inby way of example but not limitation, the first welland second wellmay comprise a first wellheadand a second wellhead. The combined well systemencompasses wellheads,may be placed in the same or separate regions. For example, wellheads,may both be located in a region that include land, ocean platforms, subsea, etc., or be separately placed in different areas from one another. Each region may include particular formation characteristics identified by rock type, porosity, thickness, and other geological information.

In some embodiments, the systemmay comprise optional hardwaresuch as a gas lift, tubing, packers, rod pumps, electrical sump pumps, hydraulic pumps, or any other equipment common in the industry. The systemmay further comprise a first tool launcher/catcherand second tool launcher/catcher.

In some embodiments, the first welland second wellmay each, respectively, comprise a first casing segmentand second casing segment, a first heel sectionand second heel section, a first toe sectionand second toe section, and a connector. First casing segmentand second casing segmentmay include a plurality of production liners that hang in their respective intermediate casings. Alternatively, the first and second casing segments,can be a tie back string of casings back to their respective wellheads,.

In some embodiments, connectormay connect the first casing segmentof the first toe sectionof the first wellto the second casing segmentof the second toe sectionof the second wellin a subterranean formation. The connectoris configured to allow at least production materials to flow between the first welland the second wellvia the first casing segmentand the second casing segment.

As illustrated in, the combined well system may use a variety of well connectors. In one embodiment, the connectormay be a screw-on connector. The screw-on connector may include the first casing segmenthaving a threaded end and the second casing segmenthaving a receiving end. The threaded end can be the end of the first casing segmentat toe end. The receiving end can be the end of the second casing segmentat the end of the toe end segment. The receiving end is configured to allow the threaded end to be inserted into the second casing segment.

In an alternative embodiment, the connectormay be an expandable tube connector, which is inserted from second casing segmentinto first casing segmentand expanded to seal the connection.

In an alternative embodiment, the connector may be an overshot connector, which is affixed to second casing segmentand fits around the outer perimeter of first casing segment.

In an alternative embodiment, the connectormay be an insertable tubewith a liner hanger or packerattached to the end of the insertable tube. The insertable tubeand the liner hanger or packermay be affixed to the end of the second casing segmentand inserted into the first casing segment, or vice versa. The liner hanger or packermay anchor to the internal wall of the first or second casing segment,, forming a sealed connection.

In an alternative embodiment, the connectormay be a gap connector. The endof first casing segmentand endof second casing segmentmay be placed such as to form a gapbetween both ends. Cementmay be placed into the gapto cement the casings,together. The gapfilled with cementmay then be drilled out such as to leave a hollow center and sealed outer portion, forming a sealed connection.

In an alternative embodiment, the connectormay be an overlap cemented connector. The first casing segmentmay be fitted inside of a portion of second casing segmentsuch that the endof first casing segmentrests inside of second casing segment, or vice versa. Cementmay then be placed in between the outer surface of endof first casing segmentand the inner surface of second casing segment, forming a sealed connection.

In an alternative embodiment, the connectormay be a side-by-side connector. The first casing segmentand second casing segmentmay run past and align parallel, or close to parallel, with one another creating a parallel section of each casing segment,. Perforationsmay be placed along the parallel sections to which the first casing segmentand the second casing segment may access the perforations. The parallel sections may be aligned such that fluid may flow freely between perforationsof the respective casings.

In an alternative embodiment, the connectormay comprise a fracture connector. The first casing segmentand second casing segmentmay run past and align parallel, or close to parallel, with one another creating a parallel section of each casing segment,. The parallel sections may include fractures in between the first casing segmentand the second casing segment, in which fluid flows through perforationson the first casing segment, through fractures, and through opposing perforationson the second casing segment.

In an alternative embodiment, the connectormay be an inflatable connector. The inflatable connectormay be comprised of elastomer material. The inflatable connectormay be affixed to the end of the second casing segmentand inserted into the first casing segment, or vice versa. The inflatable connector may include a bladder. The bladder may be filled with an inflating material. The inflating material may fill the bladder causing the elastomer material to swell to an inner surface of either the first or second casing segment,, forming a seal.

In an alternative embodiment, the connector may be a connector comprising swellable sealing elements. This may comprise an elastomer material which swells in the presence of chemical(s). These chemicals may be pumped though a connection region of the connector causing the material to swell, forming a seal.

In an alternative embodiment, the connectormay be a proprietary connector of any kind.

Referring back to, in some embodiments, the combined systemmay comprise a total casing length. The total casing lengthmay be the sum of a length of the first casing segmentand a length of the second casing segment. Alternatively, the lengthmay be measured from heelto heel. Alternatively, the lengthmay be measured from the first wellheadto the second wellhead. The combined systemmay comprise the cumulative internal cross section area of first casing segmentand second casing segment, creating a larger combined effective area open to flow as compared to the single internal cross section area of first casing segmentwith internal diameter. The completed combined systemallows for creation of a super length lateral well, as illustrated by. Lengthsandof a first and second lateral well may approach approximately.miles or more from toe-end section,to heel,respectively. The total lengthof the combined system, as measured from heelto heelalong the full bore length, may therefore be at least seven miles in length.

In some embodiments, the subterranean areamay be an area within the reservoir where the production of production material (i.e. water, oil, and gas) may take place. The subterranean areamay include an area along the super length lateral well in which the casings of the first and/or second casing segments,pass through a plurality of fracture clusters. The fracture clustersmay be natural or man-made, via fracturing. The first and/or second casing segment,may have perforations throughout their casings located in the subterranean area. The perforations are configured to allow the combined well systemto perform operations (e.g. fracking, stimulation, and injection) on the subterranean areato prepare and/or improve the fracture clustersfor oil and gas production. These improved fracture clustersmay be characterized as production clusters(not shown).

In some embodiments, the combined systemallows for full or limited bore connection. This classification of a full or limited bore connection is determined based on the use of an isolation plug. For example, if the combined well systemuses the isolation plug, the systemwill be classified as a limited connection while a combined well systemthat does not use the isolation plugis classified as a full bore connection.

In some embodiments, the systemmay allow for full bore connection into the well bore of first wellfrom the well bore of second wellor vice versa. The systemmay allow for full bore connection by either having no isolation plugin place or removing the isolation plugthat has been previously set. Through having no isolation plugin the combined well system, the combined length of first casing segmentand the second casing segmentmay have a maximum combined effective area for production to flow. By not installing isolation plugin between fracture clusters, pressure drawdown may be applied to the entirety of fracture clustersin the subterranean areafrom first welland second wellsimultaneously or independently. The simultaneous application of pressure drawdowns may improve production flow rate of the system, as discussed below.

Fracturing may occur on the system, without an isolation plug, by co-mingled fracturing as illustrated by a non-limiting embodiment illustrated in. First well fracture treatmentand second well fracture treatmentmay flow together into the same fracture clusters. This may allow for combined fracture pump rates and increased velocity and volume of proppant, leading to enhanced fracturing widths, half-length, placement, production drawdowns and increased production rates. Additionally, this method allows for subterranean mixing of treatment materials (i.e. proppants or chemicals) at the fracture clusteras pumped from surface well headand well headsimultaneously. Fluid diverters may also be used to allow for multiple co-mingled fracks stages along the entire combined well bore length. Perforation density and hole size may need to be matched to the combined pump rates.

In some embodiments, the full-bore connection may allow for hydraulic and mechanical communication from the surface of second wellto the surface of first well. For example, the communication may allow for pigging operations. The communication may allow for intervention of the toe sectionsandfrom either the first wellor the second well. For example, the systemmay allow for completion treatments to be initiated toward toe sectionsandfrom the opposing wellhead,, respectively, as discussed below.

The intervention may include a method of using a tool launcher and receiver as illustrated in. Since the combined systemmay comprise a closed hydraulic/mechanical loop, mechanical and diagnostic tools from first wellheadmay be pumped around to second wellhead. First wellheadmay comprise a first tool launcher and receiver, and second wellheadmay comprise, but not limited to, a second tool launcher and receiver. Each tool launcher may comprise a crown valve, swab cup, and mechanical or diagnostic tool. The swab cups, pigs, tools, and/or fluid may flow according to tool flow directionfrom first tool launcher and receiverto second tool launcher and receiver, or vice-versa.

Using the method as illustrated in, tools and pigs may be pumped, pulled, pushed, tractored, or allowed to free fall around the combined systemfrom first tool launcher and receiverto second tool launcher and receiverand vice versa, allowing for mechanical pig and fluid sweeps for hole cleaning. Fluid treatments and abandonment material or cement for abandonment of the entire system may also be pumped.

Referring back to, in alternative embodiments, the limited connection combined systemmay include the isolation plug. The isolation plugmay be mechanically, electrically, or hydraulically set along the super length lateral well. The isolation plugmay partition the combined well systeminto two separate regions. For example, the isolation plugmay be placed along the subterranean area, in between production clusters. The placement of the isolation plugmay increase the production rates of the combined well system, further discussed below.

In some embodiments, the combined well systemmay have multiple partitions on either side of the isolation plugas illustrated in. As illustrated in, an isolation plugmay be set into first casing segmentat a distancefrom connector. On either side of isolation plug, a packer and tubingmay be set in-between production clusters, forming distinct flow paths and flow regimes of produced fluidandto the respective wellheads,. For example, one regime may flow into inner tubing or casing, whereas a second regime may flow outside of inner tubing or casingbut within first casing segmentback to first wellhead. These flow regimes may allow for further altering of pressure drawdown.

Referring back to, the isolation plugmay create two separate regions of the combined well systemdesignated for first wellor second welloperations (ex. fracking, producing, stimulation, and injection). These separate regions may include the casing segments,of the combined systemon either side of the isolation plug. For example, the area to the left of the isolation plugmay be designated for first welloperations while the area to the right of the isolation plugmay be designated for the second welloperations. Each region may encompass production clusters(i.e. the fracture clusters). The separate regions of the combined well systemmay have their own pressure drawdown environments to facilitate separate operations, including the operations' physical effects, placed on the region by their respective well,. For example, separate pressure environments may help facilitate production and fracturing operations. These separate operations may be based on the configurations of their respective well,.