Fracking (also known hydraulic fracturing) is a technique for extracting underground resources from a well using a pressurized fluid, referred to as a fracking fluid, to stimulate and accelerate extraction of the underground fluid resource, such as energy in the form of liquid oil or natural gas. Fracking techniques are typically used on “unconventional” resource reservoirs where oil or gas is bound to surrounding rock such as by capillary forces. Injecting highly pressurized fluid into the rock surrounding an unconventional reservoir may cause the rock to fracture and release the oil or gas from the rock.
A typical fracking operation includes drilling a wellbore down to a region of an unconventional reservoir and sealing the walls of the wellbore with a casing of concrete to create a well. Completion of the well may include perforating the wellbore casing at a well depth or region near the reservoir and forcing fracking fluid (the stimulant) through the perforations and into the surrounding rock formation at a pressure sufficient to crack or fracture the rock. The factures create fairways that allow previously trapped reservoir fluids to drain back into the wellbore and be extracted from the well. A fracking fluid may be a slurry of liquids and solids, such as water mixed with solid proppant and chemical additives. After fracturing the rock, the pressure of the fracking fluid is allowed to reduce, and the newly released reservoir fluids are allowed to drain from the rock formation into the wellbore via the same casing perforations used to force fracking fluid into the rock formation.
In accordance with aspects of the present disclosure, a mining method may comprise stimulating a length along a borehole of a well, where the length including a plurality of stimulation sections alternating along the length with a plurality of extraction sections, and the stimulating including injecting pressurized fracking fluid into rock surrounding the plurality of stimulation sections. An extraction fluid may be extracted from the well simultaneously with the stimulating of the well, where the extracting includes extracting the extraction fluid from rock surrounding the plurality of extraction sections.
In an aspect, the mining method may further include expanding, from a fracking system in the borehole, at least one barrier between a stimulation section and a neighboring extraction section and forming a seal between the barrier and a casing of the borehole. In another aspect, the mining method may further include providing pressure to the pressurized fracking fluid in the fracking system, wherein the expanding the barrier includes inflating an expansion divider, such as a bladder, in the fracking system with the pressurized fracking fluid until the barrier contacts the casing of the borehole.
In accordance with aspects of the present disclosure, a fracking system may comprise a plurality of resource extraction tools, where each tool may correspond to a stage of a well and include: an outer casing; a stimulation section along a length of the respective stage; an extraction section neighboring the stimulation section along the length of the respective stage; a stimulation pathway, an extraction pathway, and a barrier. The stimulation pathway may pass through the stimulation section and the extraction section, and the stimulation pathway may be connected to a stimulation perforation in the outer casing and configured to provide a fracking fluid from the stimulation pathway to an exterior of the respective tool through the stimulation perforation. The extraction pathway also may pass through the stimulation section and the extraction section, and the extraction pathway may be connected to an extraction perforation in the outer casing and configured to drain an extraction fluid from an exterior of the respective tool through the extraction perforation and into the extraction pathway. The barrier may be positioned between the stimulation section and the extraction section, the barrier may be configured to expand beyond the outer casing and into the exterior of the respective tool and mate with a casing of a borehole, and the barrier may divide the exterior of the respective tool into a stimulation portion of the exterior and an extraction portion of the exterior.
In an aspect, the individual tools of the fracking system may further comprise a first mating section at a first end of a respective tool, and a second mating section at a second end of the respective tool. In this aspect, the first mating section may be configured to mate with a second mating section of a neighboring tool, and the first mating section may include a connection for the stimulation pathways of the respective tool and the neighboring tool, and the first mating section may include a connection for the extraction pathways of the respective tool and the neighboring tool.
Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which:
The present disclosure describes improved techniques for extracting resources from a well, including improved fracking techniques. The improved techniques may include stimulating a rock formation with pressurized fracking fluid while simultaneously draining fluid resources, such as oil, natural gas energy or other recoverable substance, from the rock formation. By maintaining pressure on fracking fluid near a simultaneous draining of resources from a reservoir, the resources may drain faster and/or with a steadier stream of resource production as compared to prior techniques. The improved techniques may also provide detection and/or mitigation of a risk of seismic activity.
When referencing elements illustrated in each of the figures, the numbered label corresponding to each element will start with a number corresponding to the figure in which it is first discussed and best illustrated. For example, if an element is first discussed with reference to
In the example of
While some example embodiments described in this disclosure demonstrate extraction from a lateral portion of a well, such as lateral wellbore 108, it is to be understood that the present disclosure is not limited to extraction from only lateral portions of a well. For example, it is to be understood that methods and tools described here may also be used in other portions of a well, such as a vertical portion of a wellbore, or a curved portion of wellbore, and/or a sloped portion of a wellbore.
As described in the various embodiments of this disclosure, pressurized stimulation of rock formations via a fracking fluid may cause a resource to drain from the rock formations. In an aspect of the various embodiments, in addition to pressurizing the fracking fluid, a pressure and/or flow speed of the draining resource may be regulated, for example by pumping the draining resource. For example, a first pump at the surface may provide pressure to the fracking fluid, while a second pump alternately or simultaneously applies suction to the draining resource. In one aspect, a pump for the draining resource may increase a speed of extraction and/or a total amount (e.g., volume) of extracted resource from the well. In another aspect, a pump for the draining resource may allow regulation of resource drain speed, such as by increasing and/or decreasing speed of resource extraction from the well. Increasing resource extraction flow speed, such as toward the end of the well's lifetime, may substantially reduce the time required to complete extraction of the resource from the well. Decreasing resource extraction flow speed may mitigate a risk of seismic events caused by draining the rock formation.
Although well 201 is illustrated as including three stages 230, 240, and 250 positioned in or near region 220, well 201 could include any number of stages. Fracking system 270 may include three energy extraction tools, each positioned within and corresponding to one of the three stages 230, 240, 250. Each stage 230, 240, 250 (and each corresponding stage tool) may include a respective stimulation section 232, 242, and 252 as well as a respective extraction section 234, 244, 254. Barriers 260 may separate stimulation sections from neighboring extraction sections.
In operation, each stage tool of the fracking system is an energy extraction tool that may enable stimulation of surrounding rock by forcing pressurized fracking fluid from the surface via the stimulation pathway to exit the wellbore via a stimulation perforation, such as stimulation perforation 256, in the annular casing 202 near the respective stimulation section. A fracking fluid may include a liquid, a slurry of liquid and solid (such as a proppant), and/or a gas (such as steam). Simultaneously to the stimulation, each energy extraction tool stage may enable extraction of resources from surrounding rock with its respective extraction section by draining the resource from the surrounding rock via an extraction perforation, such as extraction perforation 258, in the annular casing 202 near the respective extraction section, and the extracted resource may flow to the surface via the extraction pathway.
Annular casing 202 may seal the walls of a drilled wellbore, for example to prevent ground water surrounding the vertical wellbore from entering the well 201 and to prevent fracking fluid or extracted resources from contaminating any surrounding ground water. Annular casing 202 may be composed, for example, of concrete and/or a metal casing. The annular casing may vary in thickness or composition along the well 201. For example, the vertical portion of annular casing 202 above kickoff point 204 may be thicker and include concrete covered by a metal casing, while the lower portions of the wellbore below the kickoff point 204 may be thinner and composed of only concrete. In an aspect, stimulation perforations 256 and extraction perforations 258 may be created in the annular casing prior to insertion of energy extraction tools for stages 230, 240, 250.
The energy extraction tools for stages 230, 240, and 250 may each be discrete apparatus that may be inserted into a wellbore near the resource reservoir region 220 and joined together as a series of stages. Each distinct stage apparatus may include a mating section at one or both ends configured to mate and seal to neighboring stages. For example, a first end of a stage may include a male mating section and the opposite second end may include a female mating section. By mating a male mating section of a first stage to a female mating section of a neighboring stage, the stimulation pathway 212 and extraction pathway 214 in the first stage may each be joined to their respective pathways in the neighboring stage. In an aspect, the mating mechanism may be sufficient to retain fluid pressure in the pathways throughout the fracking system 270 from the lateral toe 206 all the way up to the well entrance at the surface.
As depicted in
In the example of
In an aspect, barriers 260 may be incorporated as part of the fracking system 270 and inserted into well 201 as part of energy extraction tools for respective stages 230, 240, 250. After insertion of tools into the well, the barriers 260 may be expanded beyond the outer casing 210 of the fracking system 270 and form a seal with the annular casing 202 (or another type of wellbore wall) between neighboring stimulation and extraction sections, such as between stimulation section 252 and extraction section 254 of stage 250, or between stages 240 and 250. The seal formed by the barriers 260 may be sufficient to preserve a significant pressure difference between pressurized fracking fluid in a stimulation section and the lower pressure of the extraction fluid draining into the extraction section. In an aspect, barriers 260 may be erected a pressurized mechanical expander, such as by inflating a bladder in the barrier with the pressurized fracking fluid and causing the barrier to expand until it seals with the surrounding annular casing 202 of the wellbore. In another aspect, barriers 260 may be expanded and engage the wellbore wall by an electric or electric/mechanical motor, such as an electric or electric/mechanical motor included in one or more sections of fracking system 270. In an aspect, barriers 260 may be positioned at a transition section between stimulation and extraction sections. Barriers 260 may be a mechanical device operated by pressurized lines, or an electromechanical device that is operated by signals transmitted through wiring, provided in the stages, as further discussed herein.
One or more barriers 305 may surround tool 390 and be positioned along the tool at the transition between the stimulation section 352 and extraction section 354. The one or more barriers 305 may be extendable, such that tool 390 may be inserted into the well with the barrier 305 in a retracted state, and then after tool 390 is positioned at a well stage, the barrier may be extended past outer casing 306 and away from the tool 390 to reach the well's annular casing 301 and form a seal between the barrier 305 and the annular casing 301. The barrier(s) and the seal formed may extend around the circumference of the annular casing 301 and tool 390, and the seal may maintain a pressure differential between a stimulation annular space 310 exterior of the outer casing 306 in the stimulation section 352, and an extraction annular space 318 exterior of the tool 390 in the extraction section 354.
In an aspect, stimulation pathway 311 may have a larger cross-section than stimulation pathway 314. For example, as depicted in
In operation of resource extraction tool 390, the various perforations described herein may be structural holes in the corresponding casing that allow a fluid (such as fracking fluid or any extractable/recoverable resource such as oil or natural gas resources) to flow through the corresponding casing. After inserting tool 390 into a well and sealing stimulation annular space 310 from extraction annular space 318 with barrier(s) 305, pressurized fracking fluid may come from the surface and be forced via pressure generated at the surface through stimulation pathway 311, outer casing stimulation perforation 304, stimulation annular space 310, annular casing stimulation perforation 302, and into a rock formation surrounding the well in the region of stimulation section 352. The pressure of fracking fluid may fracture the rock formation which may release previously trapped fluid resources in the rock formation and provide drainage pathways for the released resources to drain from the rock formation in the extraction section 354 into the annular casing extraction perforation 303. From there, the drained resource may continue though the extraction annular space 318 and extraction pathway 312 all the way up to the surface.
In addition, to fracturing the rock, pressurized fracking fluid may assist resource extraction by “sweeping” the rock formation from a stimulate section, such as section 352 to neighboring extraction sections, such as section 354. Fracking fluid may flood the rock formation and may help force the resources in the rock to move from stimulation perforation 302 through the rock and toward extraction perforation. Resources may be drained simultaneously and/or continuously while pressurized fracking fluid floods the rock formation surrounding the well. The sweeping process my occur in neighboring well stages simultaneously where the well is stimulated with fracking fluid at a plurality of stimulation sections (e.g., 223, 242, 252 of
In some optional aspects, tool 390 may include a mid-casing 307 inside the outer casing 306 within the stimulation section 352 to form the stimulation pathway 311 within the stimulation section 352. An inner casing 308 inside the mid-casing 307 may form the extraction pathway within the stimulation section 352. In another optional aspect, a gap 317 may be formed between the mid-casing 307 and inner casing 308. Structural spacers 309 (see
In an optional aspect, tool 390 may include a coupling for wiring at the ends of the tool. As depicted in the example of
In an optional aspect, spacers 320 may provide additional structural integrity of extraction section 354. In some implementations, stimulation pathway 314 in extraction section 354 may be divided into separate channels, and structural spacers 320 may connect the separate channels (see
Fracking systems typically include few sensors, aside from wellhead instruments, pressure sensors, temperature sensors and position sensor as wells are being drilled. By incorporating wiring coupling and/or pathways, additional sensors may be added, particularly in each stage or section, to monitor a wide variety of conditions all along the active area of the well, including pressure, temperature, frequency, sound, vibration, chemical detection, flow, radiation, etc. Sensor data may be utilized to map activity associated with a well to seismic activity in the region of the well. In an example, certain sensed conditions may be found to occasionally or regularly occur prior to seismic activity in the region of the well. When such sensed conditions are detected, the activity associated with the well may be altered to reduce or eliminate the seismic activity. In an aspect, sensor data may be used to control stimulation and/or extraction processes, such as by adjusting pressure from a pump(s) for the fracking fluid and/or extraction resource. By controlling stimulation and/or extraction, a risk of seismic activity associated with the well may be mitigated.
It will be appreciated that the fracking methods and tools discussed herein are not limited to the depicted embodiments, and other such sealing systems and methods and tools may be used to achieve the described features and benefits. While certain embodiments have been described, these embodiments have been presented by way of example only and are not intended to limit the scope of the inventions disclosed herein. For instance, the fracking techniques described herein may be applied to well topologies of different sorts, such as sloped wellbores, or wells with a single vertical wellbore section and multiple lateral wellbore sections leading in different directions from the single kickoff point. Indeed, the present disclosure described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions disclosed herein. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of certain of the inventions disclosed herein.
This application claims benefit under 35 U.S.C. § 119 (e) of Provisional U.S. Patent Application No. 63/597,211, filed Nov. 8, 2023, the contents of which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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63597211 | Nov 2023 | US |