BOREHOLE PATTERNS IN A GEOLOGICAL FORMATION

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority benefit of U.S. Provisional Application No. 63/705,353 filed Oct. 9, 2024 entitled BOREHOLE PATTERNS IN A GEOLOGICAL FORMATION, which is incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to drilling subsurface wells, including lateral sections that include fluid (liquid or gas) production or injection, including hydrocarbons and water, and methods of drilling lateral boreholes in a geological formation also known as Earth formations or Earth stratum.

BACKGROUND

In unconventional hydrocarbon production, horizontal or lateral wellbore portions are commonly employed to increase contact with a target formation and enhance the efficiency of hydraulic fracturing operations, for example. After a vertical or inclined wellbore is drilled to reach a desired subsurface depth, the trajectory of the wellbore is gradually built to a generally horizontal orientation, forming a lateral section that extends through a reservoir interval, or zone. These lateral portions expose a significantly greater length of the wellbore to the producing formation compared to traditional vertical wells, thereby providing multiple access points for hydraulic fracturing treatments. During hydraulic fracturing, high-pressure fluids are injected into the lateral wellbore portion to create fractures that propagate outward into the surrounding geological formations, increasing permeability and enabling hydrocarbons to flow more freely toward the wellbore. Characteristics of the lateral wellbore portions including, for example, geometry, orientation, and/or straightness, can contribute to a uniform initiation and/or distribution of fractures along the length of the lateral wellbore portions, directly affecting well productivity and overall recovery efficiency.

When multiple horizontal wellbores are drilled in close proximity to one another, several technical, operational, and reservoir-related risks can arise. For example, there is a risk of physical interference between the wellbores. Even small miscalculations in trajectory can lead to collisions, particular in dense drilling programs. Nearby wells can alter local stress fields, increasing the risk of borehole instability, for example, during drilling and/or production. Increased fracture density or communication between wellbores and/or wellbore portions can lead to unexpected losses of drilling fluids. Close spacing may cause fractures to propagate toward a neighboring wellbore portion and/or wellbore, thereby reducing effectiveness of stimulation.

In practice, parallel lateral wells are typically drilled, either as a multilateral well in “pitch fork” pattern, with multiple laterals from a common vertical section, or each lateral with a single vertical section drilled from the surface. Sometimes, parallel assisting lateral wells are interdigitally arranged between parallel laterals of primary producing wells. More exotic lateral borehole patterns are described, for example, in U.S. Pat. Nos. 10,982,490 and 11,846,185 to Hahn et al., the disclosures of which are incorporated by reference in their entireties.

Despite various attempts at using multilateral well designs, optimizing overall recovery efficiency from such configurations remains a technical challenge. Variations in trajectory, curvature, or spacing can result in non-uniform pressure profiles, overlapping drainage regions, and/or inefficient fracture initiation during stimulation, for example. As such, there exists a need for improved multilateral wellbore designs that enable effective drainage of distinct reservoir zones while minimizing interference between adjacent lateral portions.

SUMMARY

According to a first aspect of the present disclosure, a hydrocarbon fluid producing well comprising a borehole in a geological formation is disclosed. The borehole includes a first section drilled from a surface in a first drilling direction at a first angle relative to a vertically downward direction, a second section drilled in a second drilling direction at a second angle relative to the vertically downward direction, wherein a magnitude of the second angle is larger than a magnitude of the first angle, a building section connecting the first section and the second section, a third section drilled in a third drilling direction at a third angle relative to the vertically downward direction, wherein the magnitude of the second angle and a magnitude of the third angle differ from one another, a first curved section connecting the second section and the third section, a fourth section drilled in a fourth drilling direction at a fourth angle relative to the vertically downward direction, wherein the magnitude of the third angle and the magnitude of the fourth angle differ from one another, and a second curved section connecting the third section and the fourth section.

According to a second aspect of the present disclosure, a method of drilling a lateral borehole in a geological formation is disclosed. The method includes the steps of commencing drilling from a ground surface in a first drilling direction, at a first angle relative to a vertically downward direction, whereby creating a first section of the borehole, building to a second drilling section at a second angle relative to the vertically downward direction, wherein the second angle is larger than the first angle, defining a reservoir interval that extends substantially parallel to the second drilling direction, continuing drilling in the reservoir interval in the second drilling direction, whereby creating a second section of the borehole, steering the drilling within the reservoir interval, whereby changing a direction of drilling from the second drilling direction to a third drilling direction creates a first curved section of the borehole, continuing drilling in the reservoir interval in the third drilling direction, whereby creating a third section of the borehole, wherein the third drilling direction is not substantially parallel to the second drilling direction, steering the drilling within the reservoir interval, whereby changing a direction of drilling from the third drilling direction to a fourth drilling direction creates a second curved section of the borehole, and continuing drilling in the reservoir interval in the fourth drilling direction, whereby creating a fourth section of the borehole, wherein the fourth drilling direction is not substantially parallel to the third drilling direction.

According to a third aspect of the present disclosure, a hydrocarbon fluid producing well comprising a borehole in a geological formation is disclosed. The borehole includes a first section drilled from a surface in a first drilling direction, wherein the first drilling direction extends at a first angle relative to a vertically downward direction, a second section drilled in a second drilling direction, wherein the second drilling direction extends at a second angle relative to the vertically downward direction, wherein a magnitude of the second angle is larger than a magnitude of the first angle, a building section connecting the first section and the second section, a third section drilled in a third drilling direction relative to the vertically downward direction, wherein the second drilling direction does not extend substantially parallel to the third drilling direction, and a first angled section connecting the second section and the third section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a lateral well design having a serpentine arrangement in accordance with at least one aspect of the present disclosure.

FIG. 2A is a plan view of a borehole drilled, or otherwise formed, pursuant to a lateral well design in accordance with at least one aspect of the present disclosure.

FIG. 2B is a perspective view of the drilled borehole of FIG. 2A in accordance with at least one aspect of the present disclosure.

FIG. 2C is an elevation view of the drilled borehole of FIG. 2A in accordance with at least one aspect of the present disclosure.

FIG. 3A is a perspective view of a single borehole having a serpentine geometry in comparison to a plurality of boreholes having alternate lateral arrangements in accordance with at least one aspect of the present disclosure.

FIG. 3B is a plain view of the borehole comparison of FIG. 3A in accordance with at least one aspect of the present disclosure.

FIG. 4A is plan view of a well design having a plurality of serpentine boreholes in accordance with at least one aspect of the present disclosure.

FIG. 4B is plan view of a well design having a plurality of serpentine boreholes in accordance with at least one aspect of the present disclosure.

Like or similar reference numerals identify corresponding or similar elements throughout the Drawings. It should be understood that elements having the same or similar reference numerals in different figures represent the same or functionally similar components unless otherwise indicated.

DETAILED DESCRIPTION

A person skilled in the art will readily understand that, while the detailed description will be illustrated making reference to one or more embodiments, each having specific combinations of features and measures, many of those features and measures can be equally or similarly applied independently in other embodiments or combinations.

FIG. 1 schematically depicts a perspective view of a lateral well design 100 defining a trajectory, orientation, and/or depth of a desired borehole. The well designs described herein have at least three lateral sections connected to one another by curved sections in a serpentine, or otherwise “S” shaped, fashion. In particular, the well design 100 includes a first section 110 drilled from a ground surface in a first drilling direction. The first section 100 is used to establish an initial path from the ground surface to reach a depth where desired subsurface formations are present. As such, the first drilling direction extends at a first angle Θ₁ relative to a true vertically downward direction d_v. In various instances, the first angle Θ₁ is negligible such that the first drilling direction is substantially vertical. As used herein, “substantially vertical” means extending generally downward from the surface in the true vertically downward direction dv with a deviation from true vertical that does not materially alter the functional orientation of the borehole. Such deviation is typically within ±2 degrees from true vertical.

A second section 120 of the well design 100 is to be drilled in a substantially straight second drilling direction. The second drilling direction extends at a second angle Θ₂ relative to the vertically downward direction d_v. A building section 115 connects the first section 110 and the second section 120 to facilitate increasing an inclination angle of the borehole from vertical toward a desired horizontal orientation. As such, the second angle Θ₂ is greater than the first angle Θ₁. The second section 120 extends within a reservoir interval 150. In various instances, the reservoir interval 150 is defined between an upper face 162 and a lower face 164 of a particular geological stratum 160. In such instances, the reservoir interval 150 may be defined by the entire thickness of the geological stratum 160. In other instances, the reservoir interval 150 may be defined by a smaller thickness of the geological stratum 160. In various instances, the reservoir interval 150 extends between two or more neighboring geological strata.

The well design 100 further includes a third section 130 to be drilled along a substantially straight path in a third drilling direction. The third drilling direction extends at a third angle Θ₃ relative to the true vertically downward direction d_v. A first curved section 125 extends within the reservoir interval 150 to connect the second section 120 and the third section 130. A magnitude of the second angle Θ₂ is different than a magnitude of the third angle Θ₃ such that the second drilling direction and the third drilling direction are not substantially parallel to one another.

A fourth section 140 of the well design 100 is to be drilled along a substantially straight path in a fourth drilling direction. The fourth drilling direction extends at a fourth angle Θ₄ relative to the true vertically downward direction d_v. A second curved section 135 extends within the reservoir interval 150 to connect the third section 130 and the fourth section 140. In various instances, the fourth drilling direction extends substantially parallel to the second drilling direction. In such instances, a magnitude of the second angle Θ₂ is substantially similar to a magnitude of the fourth angle Θ₄. However, embodiments are envisioned where the fourth drilling direction does not extend substantially parallel to the second drilling direction. In any event, the magnitude of the fourth angle Θ₄ is different than the magnitude of the third angle Θ₃ such that the fourth drilling direction and the third drilling direction do not extend substantially parallel to one another.

As described herein, the second angle Θ₂ is different from the third angle Θ₃. In various instances, the second angle Θ₂ differs from the third angle Θ₃ by a magnitude between a range of 30 to 60 degrees. In various instances, the second angle Θ₂ differs from the third angle Θ₃ by a magnitude between a range of 40 to 50 degrees. In various instances, the second angle Θ₂ differs from the third angle Θ₃ by a magnitude of approximately 45 degrees. In various instances, the second angle Θ₂ differs from the third angle Θ₃ by a magnitude of approximately 45 degrees. As used herein, “approximately” refers to a deviation of up to ±2 degrees or a similar range that would be understood as functionally equivalent by a person of ordinary skill in the art.

Likewise, the fourth angle Θ₄ is different from the third angle Θ₃. In various instances, the fourth angle Θ₄ differs from the third angle Θ₃ by a magnitude between a range of 30 to 60 degrees. In various instances, the fourth angle Θ₄ differs from the third angle Θ₃ by a magnitude between a range of 40 to 50 degrees. In various instances, the fourth angle Θ₄ differs from the third angle Θ₃ by a magnitude of approximately 45 degrees. In various instances, the fourth angle Θ₄ differs from the third angle Θ₃ by a magnitude of approximately 45 degrees. As used herein, “approximately” refers to a deviation of up to ±2 degrees or a similar range that would be understood as functionally equivalent by a person of ordinary skill in the art.

As described above, a “reservoir interval” refers to the specific subsurface stratigraphic section of a geological formation that contains producible hydrocarbons. Stated another way, the “reservoir interval” refers to a target zone that the lateral borehole portion is designed to penetrate and drain. More specifically, the reservoir interval is a segment of a subsurface formation that exhibits desirable porosity, permeability, and/or hydrocarbon saturation. The three lateral sections 120, 130, 140 connected to one another by the respective curved sections 125, 135 are envisioned and depicted as existing in the same reservoir interval 150.

In various instances, it is envisioned that the well design 100 could include more than three lateral sections, such as four lateral sections, for example. In such instances, a fourth lateral section, or fifth section, would be coupled to the third lateral section, or fourth section, 140 by way of a third curved section, similar in many respects to the first and second curved section 125, 135. The fourth lateral section, or fifth section, is to be drilled along a substantially straight path in a fifth drilling direction. The fifth drilling direction extends at a fifth angle relative to the true vertically downward direction d_v. In various instances, the fifth drilling direction extends substantially parallel to the third drilling direction. In such instances, a magnitude of the fifth angle is substantially similar to a magnitude of the third angle Θ₃. However, embodiments are envisioned where the fifth drilling direction does not extend substantially parallel to the third drilling direction. In any event, the magnitude of the fifth angle is different than the magnitude of the fourth angle Θ such that the fifth drilling direction and the fourth drilling direction do not extend substantially parallel to one another.

Turning now to FIGS. 2A-2C, a borehole 200 is drilled through a geological stratum according to a well design, similar in many respects to the well design 100. A depth associated with the desired geological stratum is approached from surface 205, such as the surface of the ground, via a first section 210 of a first borehole system 200. As described with respect to the first section 110 of the well design 100, the first section 210 is a vertical borehole portion used to establish an initial path from the ground surface 205 to reach a depth where desired subsurface formations are present. At a certain kick-off point, a building section 215 begins where the drilling trajectory begins to curve toward a horizontal direction until a horizontal plane 250, or reservoir interval, is formed in the target formation 260.

Similar to the lateral portions 120, 130, 140 of the well design 100 described herein, the borehole 200 has a second section 220, a third section 230, and a fourth section 240. The second section 220 is connected to the first section 210 by way of the building section 215. The third section 230 is connected to the second section 220 by way of a first curved section 235, and the fourth section 240 is connected to the third section 230 by way of a second curved section 235. In various instances, the fourth section 240 extends substantially parallel to the second section 220, while the third section 230 does not extend substantially parallel to either of the fourth section 240 and the second section 220. So as to not unnecessarily repeat all details, similar reference numbers identify corresponding elements across the different drawings in this disclosure.

FIGS. 3A and 3B depict various views of a plurality of wellbores in a particular region. Notably, the field of wellbores includes one serpentine wellbore 300 similar in many respects to the wellbores associated with FIGS. 1-2C. The field further includes a plurality of wellbores 380 having one vertical section 385 coupled to one lateral section 395 by way of a building section 380. Notably, many wellbores 380 are needed to achieve the same reach as one serpentine wellbore 300 exemplifying the economic and efficient solution proffered by the serpentine wellbore arrangements disclosed herein. Not only does the serpentine wellbore allow for decreased wellbores, but it also reduces close spacing in between wellbores.

FIGS. 4A and 4B illustrate various well designs 400, 500 each of which utilize a plurality of boreholes. In particular, the well design 400 shown in FIG. 4A depicts two boreholes 405a, 405b with building sections 415a, 415b formed at the same depth, or in the same reservoir interval, for example, at the end of respective first vertical sections 410a, 410b. The first and second boreholes 405a, 405b are similar in many respects to the resultant borehole from the well design 100 described herein. So as to not unnecessarily repeat all details, similar reference numbers identify corresponding elements across the different drawings in this disclosure. The well design 400 depicted in FIG. 4A achieves increased reservoir exposure and advantaged drainage pattern by mirroring the serpentine pattern of the borehole with respect to one another. In various instances, such a pattern results in the intersection of sections of the boreholes. In particular, a third section 430a of the first borehole 405a intersects a third section 430b of the second borehole 405b, and a fourth section 440a of the first borehole 405a intersects a fourth section 440b of the second borehole 405a.

The well design 500 shown in FIG. 4B similarly depicts two boreholes 505a, 505b. So as to not unnecessarily repeat all details, similar reference numbers identify corresponding elements across the different drawings in this disclosure. In contrast to the boreholes 405a, 405b shown in FIG. 4A, however, the boreholes 505a, 505b shown in FIG. 4B include respective building sections 515a, 515b at different depths, for example, at the end of respective first vertical sections 510a, 510b. In such instances, the serpentine pattern formed by the first borehole 505a is formed above, or otherwise closer to a ground surface, than the serpentine pattern formed by the second borehole 505b. In any event, this well design 500 also achieves increased reservoir exposure and advantaged drainage patterns.

The well designs and/or borehole patterns described herein provide an economic and practical solution to address ineffective drainage of distinct reservoir zones achieved by known well designs with lateral borehole patterns. In particular, the serpentine borehole arrangements described herein provide various advantages over the prior art, some of which include: (a) a greater amount of surface area created to geological formations per length of bore drilled within a defined area; (b) the creation of surface area that is otherwise impossible or uneconomic for a typical lateral borehole due to space constraints, (“stranded” interests or reserves); (c) an orientation that intersects natural fracturing or the preferred direction of principal stress to facilitate effective hydraulic stimulation and injection or production; and (d) fewer wellbores (vertical and lateral) needed to effectively produce or inject a defined area. The described borehole arrangements reduce surface impact, improve development returns with less drilling costs, make stranded interests attainable, and improve well performance.

As used herein, the term “substantially parallel” refers to portions, segments, or axes of wellbores that extend in generally the same direction, allowing for minor angular deviations that do not materially affect their functional alignment. In certain instances, “substantially parallel” segments may deviate from one another by less than about 5 angular degrees, or by a lateral separation or angular variance that maintains functional parallelism within the context of the formation or completion design. Such deviations may result from geological steering, tool drive, or curvature constraints inherent in directional drilling, for example, yet are considered substantially parallel so long as the two portions remain oriented to achieve similar directional objectives or drainage zones within the reservoir.

As used herein, the term “substantially straight” refers to a portion, segment, or section of a wellbore that extends along a trajectory having negligible curvature relative to the scale and purpose of the well design. A “substantially straight” portion is one in which any deviation from a true linear path is within normal drilling tolerances or does not materially affect the intended orientation, completion geometry, or flow performance of the wellbore. Minor variations resulting from factors, such as, for example, steering adjustments, tool face response, or formation heterogeneity remain within the scope of “substantially straight” so long as the segment behaves functionally as a straight wellbore portion.

The person skilled in the art will understand that the present disclosure can be carried out in many various ways without departing from the scope of the appended claims.