Underground pipeline installation for geothermal

Abstract

The present disclosure relates to systems and methods for geothermal energy systems utilizing underground geothermal fluid transmission and distribution pipelines. In some examples, underground geothermal fluid transmission and distribution pipelines may be installed with underground expansion loops and a central anchor block that allows for controlled thermal expansion without exceeding the strength of the pipe material used for the pipelines.

Description

UNDERGROUND PIPELINE INSTALLATION FOR GEOTHERMAL APPLICATIONS CLAIM OF PRIORITY

[0001] This patent application claims the benefit of U.S. Provisional Patent Application Serial No.63 / 702,892, filed on October 3, 2024, titled “UNDERGROUND PIPELINE INSTALLATION FOR GEOTHERMAL APPLICATIONS,” the contents of which are incorporated by reference herein in its entirety. TECHNICAL FIELD

[0001] The present disclosure relates to geothermal energy production and, in some examples, to geothermal gathering and transmission pipeline installed underground utilizing underground expansion loops. BACKGROUND

[0002] The increasing demand for sustainable and renewable energy has spurred recognition of geothermal energy as a unique and important resource due to its consistent and predictable output. Historically, geothermal applications have relied on expensive and visible above-ground piping systems to harness and distribute thermal energy from the geothermal well source to the power generation plant. Above-ground piping has been utilized due to the elevated operating temperatures typical of geothermal applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Some examples are shown for purposes of illustration and not limitation in the figures of the accompanying drawings. In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views or examples. It should be understood that additional and alternative examples are possible without departing from the principles of the subject matter described herein.

[0004] FIG. 1 illustrates an example of a natural resource system, in accordance with examples described herein.

[0005] FIG. 2 illustrates an example of an underground pipeline, in accordance with examples described herein.

[0006] FIG. 3 illustrates an example of an underground pipeline, in accordance with examples described herein.

[0007] FIG. 4 illustrates an example of an underground pipeline, in accordance with examples described herein.

[0008] FIG. 5 illustrates an example of an underground pipeline, in accordance with examples described herein.

[0009] FIG. 6 illustrates an example of an underground pipeline, in accordance with examples described herein.

[0010] FIG. 7 illustrates a cross-sectional example of an underground pipeline system, in accordance with examples described herein.

[0011] FIG. 8 illustrates an example technique for installing an underground pipeline system, in accordance with examples described herein.

[0012] FIG. 9 illustrates an example of a machine upon which any one or more of the techniques discussed herein may be performed, in accordance with examples described herein. DETAILED DESCRIPTION

[0013] The systems and techniques described herein relate to geothermal energy systems utilizing underground geothermal fluid transmission and distribution pipelines. In some examples, underground geothermal fluid transmission and distribution pipelines may be installed with underground expansion loops and a central anchor block that allows for controlled thermal expansion without exceeding the strength of the pipe material used for the pipelines. The underground expansion loops and the central anchor block work together to provide controlled thermal expansion management for the pipelines. The expansion loops expand against surrounding soil material, acting as a natural spring system to absorb thermal movement. The expansion loops may be spaced out or sized based on a stress analysis that may be performed based on one or more specific properties (e.g., size,temperature, flow rate, pressure) of the geothermal field. During installation, the pipelines are installed at elevated installation temperatures to decrease the temperature difference experienced by the pipeline material between installation of the pipelines and transmission and distribution of geothermal fluid in the pipelines. Decreasing the temperature difference helps to reduce thermal stresses on the pipelines during operation.

[0014] For example, an enhanced geothermal system may utilize underground pipelines for the transmission and distribution of geothermal fluid. An underground pipeline may include expansion loops positioned at approximately 328 feet (100 meters) in opposite directions from a central anchor block. Each expansion loop may be a U-shaped section of pipeline with dimensions of approximately 59 feet x 59 feet x 59 feet (18 meters x 18 meters x 18 meters). That is, each expansion loop includes an approximately 90° bend from a straight section of pipeline, followed by an approximately 59 feet (18 meters) section of pipeline perpendicular to the straight section of pipeline, followed by an approximately 90° bend, followed by an approximately 59 feet (18 meters) section of pipeline parallel to and in the direction of the straight section of pipeline, followed by an approximately 90° bend, followed by an approximately 59 feet (18 meters) section of pipeline perpendicular to and in the direction towards the straight section of pipeline, followed by an approximately 90° bend to continue along the direction of the straight section of pipeline. Each bend in the expansion loop can be formed with 10D bends (e.g., radii of the bends are 10 times the diameter of the pipeline). The pipeline may utilize X70 grade steel with a yield strength of approximately 70 ksi (483 MPa) and wall thicknesses of approximately 1.03 inches (26 millimeters) for the expansion loop sections and A106 Grade B material for straight sections. When the pipeline is installed, the pipeline may be heated to an installation temperature of approximately 55 °F (13 °C). In this example, the underground expansion loops of the pipeline expand against the surrounding soil during the transmission and distribution of geothermal fluid. While the pipeline expands against the surrounding soil, the expansion loops maintain von Mises stresses at approximately 289 MPa with a stress ratio within allowablelimits, providing controlled thermal expansion management for the pipeline to operate at temperatures of approximately 400 °F (204 °C).

[0015] As illustrated in this example, the underground geothermal fluid transmission and distribution pipelines provide various improvements and advantages in the field of geothermal energy systems. For example, through the strategic placement of underground expansion loops and central anchor blocks, the thermal stresses experienced by the pipelines during operation may be steadily managed. The underground expansion loops function to expand against the surrounding soil to control thermal expansion movement, with the soil acting as a natural spring system to absorb thermal movement during temperature changes. Therefore, the thermal stresses experienced by the pipelines during operation are distributed and reduced to acceptable levels.

[0016] Underground installation of geothermal fluid transmission and distribution pipelines provides various improvements and advantages over above-ground pipelines. For example, underground pipelines have less visual impact compared to above-ground systems. Underground pipelines experience reduced heat loss due to soil insulation properties, making underground pipelines more efficient for the transmission and distribution of geothermal fluids. Maintenance for underground pipelines may be reduced because the pipelines are protected from weather exposure and potential damage from external sources. Therefore, the underground geothermal fluid transmission and distribution pipelines provide for improvements in the transmission and distribution of geothermal fluids while provide cost- effective and reliable operation.

[0017] In some examples, underground expansion loops expand against the surrounding soil during thermal expansion and contraction cycles of an underground pipeline to control thermal expansion movement. When the underground pipeline experiences thermal expansion due to elevated operating temperatures (e.g., approximately 400 °F (204 °C)), the underground expansion loops accommodate the thermal expansion movement by expanding outward against the soil, which provides resistance like a spring against the thermal expansion movement. The soil providesaxial, lateral, and vertical resistance forces that allow the expansion loops to absorb the thermal expansion movement and maintain pipeline integrity. In some examples, various soil types, such as silt, sand, and gravel, have different soil properties, such as levels of resistance, and these soil properties are taken into account with geotechnical characteristics, such as bulk weight and effective friction angle, in determining the dimensions and positions of the expansion loops.

[0018] In some examples, an underground expansion loop incorporates a bend with a bend radius from 10D to 20D. A 10D bend has a bend radius that is ten times the diameter of the pipe, and a 20D bend has a bend radius that is twenty times the diameter of the pipe. These bend radii provide effective thermal expansion management during temperature changes while reducing space requirements and reducing stress concentrations in the bends of the underground expansion loops. In some examples, the bend radius of a bend in an underground expansion loop is based on factors including pipeline diameter, operating temperature, pressure requirements, and soil properties.

[0019] In some examples, an underground expansion loop is positioned at a distance of approximately 328 feet (100 meters) to approximately 3,280 feet (1,000 meters) from a central anchor block of a pipeline. The section of pipeline between the expansion loops and the central anchor block may be a straight pipeline section. The spacing intervals for installing expansion loops from anchor blocks provide effective thermal stress management while allowing for extended straight pipeline runs. In general, shorter distances between the central anchor blocks and the expansion loops reduce stress concentrations in the pipeline. In some examples, the spacing intervals for expansion loops are determined based on stress analysis and buckling mitigation assessments. Various factors, such as operating temperature, pressure requirements, pipeline diameter, and soil properties, may affect the stress analysis and buckling mitigation assessments, thereby affecting the spacing intervals for expansion loops.

[0020] In some examples, an underground expansion loop has dimensions ranging from approximately 59 feet x 59 feet x 59 feet (18 meters x 18meters x 18 meters) to approximately 164 feet x 164 feet x 164 feet (50 meters x 50 meters x 50 meters). A larger underground expansion loop provides greater capacity for accommodating thermal expansion and facilitates pipelines with higher operating temperatures, extended straight pipeline lengths, or particular soil conditions. In some examples, the dimensions of an underground expansion loop are based on factors such as pipeline temperature, pressure, flow rate, soil conditions, and stress analysis calculations.

[0021] In some examples, an underground expansion loop uses materials with material strength from approximately 35 ksi (241 MPa) to approximately 70 ksi (483 MPa). Materials such as A106 Grade B steel provide a material strength of 35 ksi and may be suitable for some pipelines. Materials such as X70 steel with higher material strengths may be used to facilitate increased stress capacity. In some examples, the choice of material for an underground expansion loop may be based on factors such as operating temperature, stress distributions, and stress analysis calculations. In some examples, a material with a higher material strength is used for sections of a pipeline that are expected to operate under higher stress, and a material with a lower material strength is used for sections of the pipeline that are expected to operate under lower stress.

[0022] In some examples, an underground expansion loop has a wall thickness from approximately 0.59 inches (15 millimeters) to approximately 1.03 inches (26 millimeters). A Schedule 40 wall thickness for NPS 20 pipe applications is approximately 0.59 inches, which provides suitable structural integrity for many geothermal applications. Increasing wall thickness provides improved stress mitigation. In some examples, the wall thickness of an expansion loop is based on factors, such as operating temperatures, design pressures, thermal expansion forces, stress distributions, and stress analysis calculations.

[0023] A pipeline may include expansion loops of various characteristics based on the expected stress to be mitigated by the expansion loops. For example, the pipeline may include a first expansion loop with first dimensions (e.g., 59 feet x 59 feet x 59 feet), a first bend radius (e.g., 10D),a first material strength (e.g., 35 ksi), a first wall thickness (e.g., 0.59 inches), and positioned at a first distance (e.g., 328 feet) from a central anchor block. The pipeline may include a second expansion loop with second dimensions (e.g., 164 feet x 164 feet x 164 feet), a second bend radius (e.g., 20D), a second material strength (e.g., 70 ksi), a second wall thickness (e.g., 1.03 inches), and positioned at a second distance (e.g., 3,280 feet) from the central anchor block. The characteristics of the first expansion loop and the second expansion loop may be determined based on stress analysis calculations that indicate the expected stress to be mitigated by the first expansion loop and the second expansion loop.

[0024] In some examples, a pipeline is installed at installation temperatures ranging from approximately 55 °F (13 °C) to approximately 176 °F (80 °C). By installing the pipeline at an elevated installation temperature, the temperature differential experienced by the pipeline between installation and operating conditions is reduced. By reducing the temperature differential experienced by the pipeline, the pipeline undergoes reduced thermal expansion when the pipeline reaches operating temperatures (e.g., approximately 400 °F (204 °C)).

[0025] In some examples, a pipeline system for transmitting and distributing geothermal fluid includes production pipelines and injection pipelines. In general, production pipelines may operate at higher temperatures (e.g., 390 °F to 400 °F (199 °C to 204 °C)), and injection pipelines may operate at lower temperatures (e.g., 185 °F to 200 °F (85 °C to 93 °C)). Production pipelines may operate at higher pressures (e.g., 250 psig (1.72 MPa)), and injection pipelines may operate at lower pressures (e.g., 85 psig (0.59 MPa)). In some examples, the inclusion of expansion loops and the characteristics of the expansion loops may be based on whether a pipeline is a production pipeline or an injection pipeline. For example, a production pipeline may include expansion loops with characteristics based on a higher expected thermal stress than the expansion loops of an injection pipeline. The expansion loops of the production pipeline may, for example, have larger expansion loop dimensions, have a larger bend radius, use materials with higher material strength, have thicker walls, and be positionedcloser to a central anchor block than the expansion loops of the injection pipeline.

[0026] In some examples, a central anchor block acts to hold a section of a pipeline in a fixed position, resisting axial, lateral, and vertical forces. In some examples, a pipeline may include multiple anchor blocks along the length of the pipeline. Anchor blocks may alternate with expansion loops along the length of the pipeline to maintain stability against thermal expansion along the length of the pipeline. In some examples, anchor blocks may be placed successively along the length of the pipeline, or expansion loops may be placed successively along the length of the pipeline to account for various environmental conditions, such as to direct the pipeline around an environmental obstacle or around existing infrastructure.

[0027] In some examples, an underground pipeline is buried at a depth of approximately 5 feet (1.5 meters) to approximately 10 feet (3 meters) below the surface. The depth of the underground pipeline may be adjusted based on environmental conditions, such as frost lines, and other considerations. In some examples, an underground pipeline may have various sizes to accommodate flow. For example, NPS 16 and NPS 20 pipeline sizes may be used to accommodate different rates of flow. As the rate of flow affects the magnitude of thermal forces, expansion loop characteristics may be determined based on pipeline sizes.

[0028] In some examples, stress analysis calculations are performed to evaluate thermal stresses and structural integrity of a pipeline system before installation of the pipeline system underground. The stress analysis calculations include, for example, soil spring calculations to determine axial, lateral, and vertical resistance values based on soil parameters, such as bulk weight, effective friction angle, and geotechnical characteristics. The stress analysis calculations may include buckling assessments to evaluate upheaval, lateral, and downward buckling potential under thermal loading conditions. The stress analysis calculations may include stress ratio calculations to compare calculated stresses against allowable stress limits.

[0029] In some examples, a geotechnical investigation and stress analysis are performed prior to the installation of an underground pipeline system.The geotechnical investigation includes field exploration, subsurface exploration, representative soil sampling, laboratory testing, and engineering analyses to evaluate soil conditions and potential risks associated with underground installation. The stress analysis incorporates various calculations, including soil spring calculations and buckling analysis, to determine axial, lateral, upward, and downward resistance values based on soil parameters such as bulk weight, effective friction angle, and other geotechnical characteristics. Global buckling analysis is performed to evaluate upheaval buckling, lateral buckling, and downward buckling potential under thermal loading conditions using established formulas and methodologies. Local buckling evaluation determines whether the selected wall thickness is adequate to control localized instability of pipe walls due to pressure and thermal loads. The stress analysis facilitates effective design of expansion loop spacing, anchor block positioning, and material specifications to manage thermal stresses to remain within acceptable limits during operation.

[0030] The systems and methods described herein have various applications in geothermal energy systems. For example, the underground pipeline systems described herein may be used with enhanced geothermal systems and traditional geothermal systems.

[0031] FIG. 1 illustrates an example 100 of a natural resource system 102, in accordance with examples described herein. For example, the natural resource system 102 may pump fluid or gas from one or more geothermal energy sources. Typically, in the production of natural resources from formations within the earth, a well or borehole is drilled into the earth to the location where the natural resource is believed to be located. These natural resources may be a heat source for geothermal energy, a hydrocarbon reservoir containing natural gas, crude oil, and combinations of these; the natural resource may be fresh water, or it may be some other natural resource that is located within the ground.

[0032] Generally, when a well is drilled into these formations, the natural resources rarely flow into and out of the formations and into the well at rates, durations, and amounts that are economically viable. This problemcan relate to the viscosity of the natural resource, the porosity of the formation, the geology of the formation, the formation pressures, and the perforations that place the production tubing in the well in fluid communication with the formation, to name a few.

[0033] In drilling a well, an initial borehole is made into the earth. Then, subsequent and smaller-diameter boreholes are drilled to extend the overall depth of the borehole. In this manner, as the overall borehole gets deeper, its diameter becomes smaller, resulting in what can be envisioned as a telescoping assembly of holes with the largest diameter hole being at the top of the borehole, closest to the surface of the earth.

[0034] Typically, when completing a well, it is necessary to perform a perforation operation. In general, when a well has been drilled and casing (e.g., a metal pipe) is run to the prescribed depth, the casing is typically cemented in place by pumping cement down and into the annular space between the casing and the earth. The casing, among other things, prevents the hole from collapsing and fluids from flowing between permeable zones in the annulus. Thus, this casing forms a structural support for the well and a barrier to the earth.

[0035] Boreholes are generally formed and advanced by using mechanical drilling equipment having a rotating drilling tool (e.g., a bit). For example, when creating a borehole in the earth, a drilling bit is extended to and into the earth and rotated to create a hole in the earth. In general, to perform the drilling operation, the bit must be forced against the material to be removed with a sufficient force to exceed the shear strength, compressive strength, or combinations thereof of that material.

[0036] As illustrated in FIG. 1, the natural resource system 102 can inject a fluid or a gas through a subsurface 104 via an injection well 108 to fractures 110a, 110b, 110c. The fractures 110a, 110b, 110c can be part of an enhanced geothermal system, which can be a man-made reservoir created where there is hot rock but insufficient or little natural permeability or fluid saturation. In some instances, fluid or gas can be injected through the injection well 108 to cause the fractures 110a, 110b, 110c to open or re-open to create permeability. In some instances, fluid or gas can be injectedthrough the injection well 108 as part of a flow through the fractures 110a, 110b, 110c. The flow through the fractures 110a, 110b, 110c can be enhanced through reservoir stimulation. Here, stimulation of multiple fractures, such as the fractures 110a, 110b, 110c, allows for an area to be stimulated in a series of smaller stimulations, minimizing local stress perturbations. The stimulation of multiple fractures provides for access to significantly more of the reservoir and provides additional flow opportunities, increasing overall flow rate. For example, through multizone stimulation, flow rates of 40-80 kg / s for commercial production may be achieved, where stimulation of a single fracture may fail to achieve a flow greater than 25 kg / s.

[0037] As illustrated in FIG. 1, fluid or gas can flow from the fractures 110a, 110b, 110c to the natural resource system 102 through the subsurface 104 via a production well 106. The natural resource system 102 can extract energy (e.g., heat, thermal energy) from the fluid or the gas from the fractures 110a, 110b, 110c. As illustrated in FIG. 1, the injection well 108 and the production well 106 can be horizontal wells. The injection well 108 and the production well 106 can have limited-entry completion designs to maximize thermal sustainability. In general, limited-entry completion designs refer to well stimulation techniques that effectively treat multiple zones simultaneously. Through limited entry completion designs, even stimulation and uniform flow can be achieved.

[0038] FIG. 2 illustrates an example of an underground pipeline 200, in accordance with examples described herein. The underground pipeline 200 may be, for example, a production pipeline or an injection pipeline of an underground pipeline system. For example, the underground pipeline 200 may be utilized for the transmission and distribution of geothermal fluid.

[0039] In FIG. 2, the underground pipeline 200 includes a pipeline segment between a first anchor block 202 and a second anchor block 212. The first anchor block 202 may be, for example, a first reinforced concrete structure that holds a first portion of the underground pipeline 200 in a fixed position, resisting axial, lateral, and vertical forces. The second anchor block 212 may be, for example, a second reinforced concrete structure that holds asecond portion of the underground pipeline 200 in a fixed position, resisting axial, lateral, and vertical forces.

[0040] The underground pipeline 200 includes an expansion loop located between the first anchor block 202 and the second anchor block 212. As illustrated in FIG. 2, the expansion loop is a U-shaped section of the underground pipeline 200 formed by a first bend 204, a second bend 206, a third bend 208, and a fourth bend 210. The first bend 204, the second bend 206, the third bend 208, and the fourth bend 210 may have bend radii ranging from 10D to 20D. For example, if the underground pipeline 200 has a diameter of 16 inches (406 millimeters), and the first bend 204 is a 10D bend, then the first bend 204 has a bend radius of 160 inches (4.06 meters). If the underground pipeline 200 has a diameter of 20 inches (508 millimeters), and the first bend 204 is a 20D bend, then the first bend 204 has a bend radius of 400 inches (10.16 meters).

[0041] As illustrated in FIG. 2, the first bend 204, the second bend 206, the third bend 208, and the fourth bend 210 each form 90° bends. In some examples, the first bend 204, the second bend 206, the third bend 208, and the fourth bend 210 are equidistant from each other. For example, for an expansion loop with dimensions of 59 feet x 59 feet x 59 feet (18 meters x 18 meters x 18 meters), the first bend 204 is 59 feet (18 meters) from the second bend 206. The second bend 206 is 59 feet (18 meters) from the third bend 208. The third bend 208 is 59 feet (18 meters) from the fourth bend 210. The first bend 204 and the fourth bend 210 are also 59 feet (18 meters) apart. Utilizing equidistant bends helps to distribute thermal stress along the expansion loop during operation.

[0042] The structure of the expansion loop is U-shaped, as formed by the first bend 204, the second bend 206, the third bend 208, and the fourth bend 210. As illustrated in FIG. 2, the first bend 204 and the second bend 206 form a pipeline segment perpendicular to the underground pipeline 200. The second bend 206 and the third bend 208 form a pipeline segment parallel to the underground pipeline 200. The third bend 208 and the fourth bend 210 form a pipeline segment perpendicular to the underground pipeline 200.

[0043] For purposes of illustration, and by way of example, the underground pipeline 200 includes a length of 7972 feet (2430 meters) from the first anchor block 202 to the first bend 204, a length of 164 feet (50 meters) from the first bend 204 to the second bend 206, a length of 164 feet (50 meters) from the second bend 206 to the third bend 208, a length of 164 feet (50 meters) from the third bend 208 to the fourth bend 210, and a length of 656 feet (200 meters) from the fourth bend 210 to the second anchor block 212.

[0044] The structure of the expansion loop accommodates thermal expansion experienced by the underground pipeline 200 during operation by expanding outwards against the surrounding soil, which absorbs thermal movement. The U-shaped structure of the expansion loop allows the expansion loop to expand against the surrounding soil so that the surrounding soil provides axial, lateral, and vertical resistance forces that absorb the thermal movement.

[0045] FIG. 3 illustrates an example of an underground pipeline 300, in accordance with examples described herein. The underground pipeline 300 may be, for example, a production pipeline or an injection pipeline of an underground pipeline system. For example, the underground pipeline 300 may be utilized for the transmission and distribution of geothermal fluid.

[0046] In FIG. 3, the underground pipeline 300 includes a first expansion loop 302, a central anchor block 304, and a second expansion loop 306. The first expansion loop 302 and the second expansion loop 306 may be, for example, U-shaped sections of the underground pipeline 300 that provide thermal stress management for the underground pipeline 300. The central anchor block 304 may be, for example, a reinforced concrete structure that holds a portion of the underground pipeline 300 in a fixed position, resisting axial, lateral, and vertical forces.

[0047] In some examples, the first expansion loop 302 and the second expansion loop 306 have corresponding dimensions. For example, the first expansion loop 302 may have dimensions of 164 feet x 164 feet x 164 feet (50 meters x 50 meters x 50 meters). The second expansion loop 306 has corresponding dimensions of 164 feet x 164 feet x 164 feet (50 meters x 50meters x 50 meters). The first expansion loop 302 and the second expansion loop 306 may have corresponding characteristics, such as bend radius, wall thickness, and material strength. In some examples, the first expansion loop 302 and the second expansion loop 306 are equidistant from the central anchor block 304. For example, the first expansion loop 302 and the second expansion loop 306 may be 3,280 feet (1,000 meters) from the central anchor block 304. By maintaining matching or corresponding characteristics, the first expansion loop 302 and the second expansion loop 306 maintain a relatively uniform stress distribution through the underground pipeline 300.

[0048] For purposes of illustration, and by way of example, the underground pipeline 300, in one example, has the first expansion loop 302 and the second expansion loop 306 positioned 328 feet (100 meters) from the central anchor block 304. The first expansion loop 302 and the second expansion loop 306 have dimensions of 164 feet x 164 feet x 164 feet (50 meters x 50 meters x 50 meters). In another example, the underground pipeline 300 has the first expansion loop 302 and the second expansion loop 306 positioned 328 feet (100 meters) from the central anchor block 304. The first expansion loop 302 and the second expansion loop 306 have dimensions of 59 feet x 59 feet x 59 feet (18 meters x 18 meters x 18 meters). In another example, the underground pipeline 300 has the first expansion loop 302 and the second expansion loop positioned 3,280 feet (1,000 meters) from the central anchor block 304. The first expansion loop 302 and the second expansion loop 306 have dimensions of 59 feet x 59 feet x 59 feet (18 meters x 18 meters x 18 meters).

[0049] In some examples, an underground pipeline system may use an underground pipeline, such as the underground pipeline 300, with expansion loops at calculated distances from anchor blocks to manage thermal stresses experienced by the underground pipeline. In general, increasing the dimensions of the expansion loops (e.g., increasing the size of the expansion loops) allows for a reduction in the number of expansion loops utilized in an underground pipeline. Decreasing the distance of the expansion loops from anchor blocks (e.g., decreasing straight pipeline lengths) reduces stresses experienced along the underground pipeline. By analyzing the soil conditions around the underground pipeline system, the characteristics of theunderground pipelines may be determined to reduce the thermal stresses experienced by the underground pipelines to acceptable levels.

[0050] FIG. 4 illustrates an example of an underground pipeline 400, in accordance with examples described herein. The underground pipeline 400 may be, for example, a production pipeline or an injection pipeline of an underground pipeline system. For example, the underground pipeline 400 may be utilized for the transmission and distribution of geothermal fluid.

[0051] In FIG. 4, the underground pipeline 400 includes an expansion loop with a first bend 402 and a second bend 404 that experience relatively higher thermal stress compared to the rest of the expansion loop and higher than, for example, a straight length section 406 of the underground pipeline 400. Through various iterations and designs of underground pipelines, the bends that connect the expansion loop to the underground pipeline, such as the first bend 402 and the second bend 404 of the underground pipeline 400, experience the most thermal stress of the pipeline. Therefore, by targeting stress management strategies towards reducing the thermal stress experienced at the bends that connect the expansion loop to the underground pipeline, the overall stress experienced by the underground pipeline may be brought to acceptable levels.

[0052] For purposes of illustration, and by way of example, the underground pipeline 400, in one example, may include the expansion loop at 1,215 meters from an anchor block. The expansion block may include 10D bends, have a 20-inch diameter, and have a 0.59-inch wall thickness. The expansion loop may have dimensions of 164 feet x 164 feet x 164 feet. The first bend 402 of this underground pipeline 400 may experience von- Mises stresses of 781 MPa, expansion stresses of 728 MPa, and an axial displacement of approximately 1331 millimeters. The second bend 404 of this underground pipeline 400 may experience von-Mises stresses of 405 MPa, expansion stresses of 362 MPa, and an axial displacement of approximately 423 millimeters. In this example, the von-Mises stresses of the first bend 402 are 363% of the acceptable stress levels, and the expansion stresses of the first bend 402 are 247% of the acceptable stress levels. The von-Mises stresses of the second bend 404 are 194% of the acceptable stresslevels, and the expansion stresses of the second bend 404 are 130% of the acceptable stress levels. As the von-Mises stresses and the expansion stresses of the first bend 402 and the second bend 404 are over acceptable stress levels, the design for this underground pipeline 400 does not sufficiently manage thermal stresses.

[0053] In another example, the underground pipeline 400 may include the expansion loop at 1,017 feet (310 meters) from an anchor block. The expansion loop may include 20D bends, have a 20-inch diameter, and have a 1.03-inch wall thickness. The expansion loop may have dimensions of 203 feet x 203 feet x 203 feet. The expansion loop may use materials with a material strength of 70 ksi. In this example, the first bend 402 may experience von-Mises stresses of 259 MPa, expansion stresses of 199 MPa, and axial displacement of approximately 371 millimeters. The second bend 404 may experience von-Mises stresses of 199 MPa, expansion stresses of 205 MPa, and axial displacement of approximately 271 millimeters. Here, the von-Mises stresses of the first bend 402 are 60% of the acceptable stress levels, and the expansion stresses of the first bend 402 are 96% of the acceptable stress levels. The von-Mises stresses of the second bend 404 are 46% of the acceptable stress levels, and the expansion stresses of the second bend 404 are 99% of the acceptable stress levels. As the von-Mises stresses and the expansion stresses of the first bend 402 and the second bend 404 are within acceptable stress levels, the design for this underground pipeline 400 may manage thermal stresses during operation.

[0054] FIG. 5 illustrates an example of an underground pipeline 500, in accordance with examples described herein. The underground pipeline 500 may be, for example, a production pipeline or an injection pipeline of an underground pipeline system. For example, the underground pipeline 500 may be utilized for the transmission and distribution of geothermal fluid.

[0055] In FIG. 5, the underground pipeline 500 includes multiple expansion loops, and thermal stress is evaluated at a bend 502 of one of the expansion loops. As the bends where the expansion loops connect to the underground pipeline 500 experience the most thermal stress of the underground pipeline 500, stress management strategies are targeted towards reducing the stress atthese bends, bringing the overall stress experienced by the underground pipeline 500 to acceptable levels.

[0056] For purposes of illustration, and by way of example, the underground pipeline 500 is a production pipeline that includes expansion loops at 328 feet (100 meters) from anchor blocks. The expansion loops may have dimensions of 59 feet x 59 feet x 59 feet (18 meters x 18 meters x 18 meters). The expansion loops may include 10D bends, have a 20-inch diameter, and have a wall thickness of 0.59 inches. The expansion loops may use a material with a 70 ksi material strength. The expansion loops may be installed at an installation temperature of 55 °F. In this example, the bend 502 may experience von-Mises stresses of 247MPa, expansion stresses of 202 MPa, and an axial displacement of approximately 231 millimeters. The von-Mises stresses are 57% of the acceptable stress levels, and the expansion stresses are 98% of the acceptable stress levels. As the stress levels are within acceptable stress levels, the design for the underground pipeline 500 may manage thermal stresses during operation.

[0057] FIG. 6 illustrates an example of an underground pipeline 600, in accordance with examples described herein. The underground pipeline 600 may be, for example, a production pipeline or an injection pipeline of an underground pipeline system. For example, the underground pipeline 600 may be utilized for the transmission and distribution of geothermal fluid.

[0058] In FIG. 6, the underground pipeline 600 includes an expansion loop, and thermal stress is evaluated at a bend 602 of the expansion loop. As the bend 602, where the expansion loop connects to the underground pipeline 600, experiences the most thermal stress of the underground pipeline 600, stress management strategies are targeted towards reducing the stresses at the bend 602, bringing the overall stress experienced by the underground pipeline 600 to acceptable levels.

[0059] For purposes of illustration, and by way of example, the underground pipeline 600 is an injection pipeline that includes expansion loops at 328 feet (100 meters) from anchor blocks. The expansion loops may have dimensions of 59 feet x 59 feet x 59 feet (18 meters x 18 meters x 18 meters). The expansion loops may include 10D bends, have a 20-inchdiameter, and have a wall thickness of 0.59 inches. The expansion loops may use a material with a 70 ksi material strength. The expansion loops may be installed at an installation temperature of 55 °F. In this example, the bend 602 may experience von-Mises stresses of 218 MPa, expansion stresses of 190 MPa, and an axial displacement of approximately 195 millimeters. The von-Mises stresses are 50% of the acceptable stress levels, and the expansion stresses are 92% of the acceptable stress levels. As the stress levels are within acceptable stress levels, the design for the underground pipeline 600 may manage thermal stresses during operation.

[0060] FIG. 7 illustrates a cross-sectional example of an underground pipeline system 700, in accordance with examples described herein. As illustrated in FIG. 7, the underground pipeline system 700 includes an underground pipeline 702 buried in the soil 704. The underground pipeline 702 may be, for example, a production pipeline or an injection pipeline. For example, the underground pipeline 702 may be utilized for the transmission and distribution of geothermal fluid.

[0061] In some examples, the underground pipeline 702 is uninsulated. FIG. 7 illustrates the heat loss from the fluid flowing through the underground pipeline 702 to the soil 704. A thermal loss analysis may be performed to evaluate the heat transfer characteristics of the underground pipeline 702. By determining the amount of heat loss from fluid flowing in the underground pipeline 702 to the soil 704, a determination may be made as to whether the soil 704 is an effective insulator for a given length of the underground pipeline 702.

[0062] In some examples, the thermal loss analysis assumes a two- dimensional, steady-state heat transfer and assumes thermal resistance from fluid convection, steel conduction, and surface convection is negligible. These assumptions maximize the predicted heat loss of the thermal loss analysis, providing a conservative buffer in the determination of the soil 704 as an effective insulator. In some examples, the thermal loss analysis may calculate the heat loss and fluid temperature loss per length of the underground pipeline 702 based on pipe diameter (D), soil thermal conductivity (ksoil), temperature difference between the fluid in theunderground pipeline 702 and the soil (Tfluid - Tsoil), and burial depth (Z). In general, heat loss per length of pipeline increases with increasing pipe diameter, increasing soil thermal conductivity, increasing temperature difference, and decreasing burial depth. For a given rate of heat loss, the drop in fluid temperature per length of pipeline decreases with increasing flow rate and increasing fluid specific heat (Cp). The thermal loss analysis may also consider the fluid flow rate and the fluid density.

[0063] For example, the following table illustrates thermal analysis results for one mile of the underground pipeline 702:

[0064] The above table illustrates an example where the soil 704, which may be dry sand, is sufficient for insulation for a one-mile length of the underground pipeline 702.

[0065] In some examples, soil analysis may be performed to evaluate the soil spring of the surrounding soil of an underground pipeline. Soil spring calculations provide resistance values for axial, lateral, upward, and downward forces based on soil parameters, such as bulk weight, effective friction angle, and other geotechnical characteristics. For example, a formula for soil spring is:where Ø is the effective friction angle, E is the Young’s Modulus of the soil, ^bis the bulk weight, ^t is the shear zone thickness at the pipeline-soil interaction, D is the pipeline diameter, and K0is a coefficient representing soil compressibility or soil spring. In performing the soil analysis, various soil types, including loose sand, dense sand, gravelly soils, and silt may be considered. As different soil types have different bulk weights and effective friction angles affecting the calculated resistance values, the soil analysis facilitates effective installation of expansion loops and anchor blocks to a pipeline to account for the soil spring around the pipeline.

[0066] In some examples, global buckling analysis may be performed to evaluate buckling potential under operating conditions. The global buckling analysis may consider upheaval buckling, lateral buckling, and downward buckling. Upheaval buckling considers the upward movement of a pipeline due to, for example, temperature increases, internal pressure, ground movements, and soil resistance. Lateral buckling considers the lateral movement of the pipeline due to, for example, temperature increases, internal pressure, ground movements, and soil resistance. Downward buckling considers the downward movement of the pipeline due to, for example, temperature increases, internal pressure, ground movements, and soil resistance.

[0067] For example, a formula for upward buckling is:where p is upwards resistance (N / m), q is axial resistance (N / m), Awis steel area (m2), E is Young’s Modulus (207 x 109Pa), I is moment of inertia (m4), and Fup is the upward buckling force. An upward buckling force that exceeds a threshold force may indicate that a pipeline may experience excessive upward buckling force during operation. Upward buckling force may be managed using expansion loops and anchor blocks during installation to resist the upward buckling force.

[0068] For example, a formula for lateral buckling is:where r is lateral resistance (N / m), q is axial resistance (N / m), Aw is steel area (m2), E is Young’s Modulus (207 x 109Pa), I is moment of inertia (m4), and Flateral is lateral buckling force. A lateral buckling force that exceeds a threshold force may indicate that a pipeline may experience excessive lateral buckling force during operation. Lateral buckling force may be managed using expansion loops and anchor blocks during installation to resist the lateral buckling force.

[0069] For example, a formula for downward buckling is:where s is downwards resistance (N / m), q is axial resistance (N / m), Awis steel area (m2), E is Young’s Modulus (207 x 109Pa), I is moment of inertia (m4), and Fdownis downward buckling force. A downward buckling force that exceeds a threshold force may indicate that a pipeline may experience excessive lateral buckling force during operation. Downward buckling forcemay be managed using expansion loops and anchor blocks during installation to resist the downward buckling force.

[0070] In some examples, axial force estimations may be performed to evaluate axial forces acting on an underground pipeline under operating conditions. The axial force estimations describe the forces acting along the longitudinal axis of the underground pipeline due to, for example, thermal expansion, internal pressure, and soil friction. For example, a formula for axial force estimation is:where v is Poisson’s ratio (0.3), ^his hoop stress (ksi), E is Young’s modulus (30,000 ksi), ^ is a thermal coefficient (6.6x10-6 / °F), ^T is a difference between design temperature and installation temperature (°F), As is cross-sectional area, and Faxial_load is an estimated axial force. An estimated axial force that exceeds a threshold force may indicate that a pipeline may experience excessive axial force during operation. Axial force may be managed using expansion loops and anchor blocks during installation to resist the axial force.

[0071] In some examples, local buckling evaluation may be performed to evaluate buckling potential of an underground pipeline during operating conditions. The local buckling analysis considers the potential for buckling forces causing localized instability of pipe walls due to pressure and thermal loads. For example, a formula for local buckling may be:where E is Young’s modulus (30,000 ksi), t is wall thickness (in.), R is inside radius of a pipeline plus half of the wall thickness (in.), and ^cr is a buckling stress. The buckling stress is compared to an axial stress to determine if local buckling is expected to occur.

[0072] For example, a formula for axial stress is:where v is Poisson's ratio (0.3), ^his hoop stress (ksi), E is Young’s modulus (30,000 ksi), ^ is a thermal coefficient (6.6x10-6 / °F), ^T is a difference between design temperature and installation temperature (°F), and ^axial_stressis an axial stress. If the axial stress is below the buckling stress, then local buckling is not expected to occur. If the axial stress is equal to or above the buckling stress, then local buckling may occur.

[0073] FIG. 8 illustrates a flow diagram of an example technique 800 for installing an underground pipeline system, in accordance with examples described herein. One or more of the functions described in the example technique 800 may be implemented in accordance with the underground pipelines of FIGS. 1-7 or a similar underground pipeline system. Although the flowchart depicts a particular sequence of operations, the sequence may be altered without departing from the scope of the subject matter disclosed herein. For example, some of the operations depicted may be performed in parallel or in a different sequence without materially affecting the functions described in the example technique 800.

[0074] At operation 802, thermal stress and structural integrity are evaluated for an underground pipeline system based on stress analysis calculations. For example, the stress analysis calculations may include soil spring calculations, global buckling analysis, and local buckling analysis to determine potential forces and resistances to account for in managing thermal stresses in the underground pipeline system.

[0075] At operation 804, the underground pipeline system is designed to incorporate expansion loops and anchor blocks to manage the thermal stress and maintain the structural integrity. For example, based on the stress analysis calculations, expansion loops and anchor blocks are incorporated into a design of an underground pipeline system to manage the thermal stresses in the underground pipeline system. Various parameters, such as wall thickness, pipeline diameter, material strength, bend radius, and distances between expansion loops and anchor blocks may also be based on the stress analysis.

[0076] At operation 806, the underground pipeline system is installed. For example, underground pipelines are placed at elevated installation temperatures (e.g., 55 °F to 176 °F (13 °C to 80 °C)) to reduce temperature differential between installation conditions and operating conditions. Installation of the underground pipeline system may include excavation to accommodate the geometry of expansion loops and anchor blocks. EXAMPLE MACHINE

[0077] FIG. 9 illustrates generally an example of a block diagram of a machine 900 upon which any one or more of the techniques (e.g., methodologies) discussed herein may perform in accordance with some examples. In alternative examples, the machine 900 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 900 may operate in the capacity of a server machine, a client machine, or both in server-client network environments. In an example, the machine 900 may act as a peer machine in a peer-to-peer (P2P) (or other distributed) network environment. The machine 900 may be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), or other computer cluster configurations.

[0078] Examples, as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms. Modules are tangible entities (e.g., hardware) capable of performing specified operations when operating. A module includes hardware. In an example, the hardware may be specifically configured to carry out a specific operation (e.g., hardwired). In an example, the hardware may include configurableexecution units (e.g., transistors, circuits, etc.) and a computer-readable medium containing instructions, where the instructions configure the execution units to carry out a specific operation when in operation. The configuration may occur under the direction of the execution units or a loading mechanism. Accordingly, the execution units are communicatively coupled to the computer-readable medium when the device is operating. In this example, the execution units may be a member of more than one module. For example, under operation, the execution units may be configured by a first set of instructions to implement a first module at one point in time and reconfigured by a second set of instructions to implement a second module.

[0079] Machine (e.g., computer system) 900 may include a hardware processor 902 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 904 and a static memory 906, some or all of which may communicate with each other via an interlink (e.g., bus) 908. The machine 900 may further include a display unit 910, an alphanumeric input device 912 (e.g., a keyboard), and a user interface (UI) navigation device 914 (e.g., a mouse). In an example, the display unit 910, alphanumeric input device 912, and UI navigation device 914 may be a touch screen display. The machine 900 may additionally include a storage device (e.g., drive unit) 916, a signal generation device 918 (e.g., a speaker), a network interface device 920, and one or more sensors 921, such as a global positioning system (GPS) sensor, compass, accelerometer, or another sensor. The machine 900 may include an output controller 928, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

[0080] The storage device 916 may include a machine-readable medium 922 that is non-transitory on which is stored one or more sets of data structures or one or more instructions 924 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The one or more instructions 924 may also reside, completely or at least partially, within the main memory 904, within static memory 906, or withinthe hardware processor 902 during execution thereof by the machine 900. In an example, one or any combination of the hardware processor 902, the main memory 904, the static memory 906, or the storage device 916 may constitute machine-readable media.

[0081] While the machine-readable medium 922 is illustrated as a single medium, the term “machine-readable medium” may include a single medium or multiple media (e.g., a centralized or distributed database, or associated caches and servers) configured to store the one or more instructions 924.

[0082] The term “machine readable medium” may include any medium that is capable of storing, encoding, or carrying instructions for execution by the machine 900 and that cause the machine 900 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting machine-readable medium examples may include solid-state memories, optical media, and magnetic media. Specific examples of machine-readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

[0083] The one or more instructions 924 may further be transmitted or received over a communications network 926 using a transmission medium via the network interface device 920 utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), and wireless data networks (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards known as Wi-Fi®, IEEE 802.16 family of standards known as WiMax®), IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, among others. In an example, thenetwork interface device 920 may include one or more physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more antennas to connect to the communications network 926. In an example, the network interface device 920 may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple- output (MIMO), or multiple-input single-output (MISO) techniques. The term “transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding, or carrying instructions for execution by the machine 900, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software. GLOSSARY

[0084] Generally, the term “about”, “approximately”, and the symbolas used herein, unless stated otherwise, is meant to encompass a variance or range of ±10%, the experimental or instrument error associated with obtaining the stated value, and preferably the larger of these.

[0085] As used herein, unless specified otherwise, the terms “formation”, “reservoir”, “pay zone”, and similar terms are to be given their broadest possible meanings, and include all locations, areas, and geological features within the earth that contain, may contain, or are believed to contain, a desired resource (e.g., geothermal heat, hydrocarbons, etc.).

[0086] As used herein, unless specified otherwise, the terms “field”, “oil field”, “geothermal field”, and similar terms are to be given their broadest possible meanings, and include any area of land, sea floor, or water that is loosely or directly associated with a formation, and more particularly, with a resource containing formation. Thus, a field may have one or more exploratory and producing wells associated with it. A field may have one or more governmental bodies or private resource leases associated with it. A field may be directly associated with a resource containing formation.

[0087] As used herein, unless specified otherwise, the terms “geothermal”, “geothermal well”, “geothermal resource”, “geothermal energy”, and similar terms are to be given their broadest possible meanings, and include systemsand operations, including wells, that recover or utilize the heat energy that is contained within the earth. Such systems and operations include enhanced geothermal wells, engineered geothermal wells, binary cycle power plants, dry steam power plants, flash steam power plants, open-loop systems, and closed-loop systems.

[0088] As used herein, unless specified otherwise, the term “earth” should be given its broadest possible meaning, and includes, the ground, all natural materials, such as rocks, and artificial materials, such as concrete, that are or may be found in the ground, including without limitation rock layer formations, such as, granite, basalt, sandstone, dolomite, sand, salt, limestone, rhyolite, quartzite and shale rock.

[0089] As used herein, unless specified otherwise, the term “borehole” should be given it broadest possible meaning and includes any opening that is created in a material, a work piece, a surface, the earth, a structure (e.g., building, protected military installation, nuclear plant, offshore platform, or ship), or in a structure in the ground, (e.g., foundation, roadway, airstrip, cave or subterranean structure) that is substantially longer than it is wide, such as a well, a well bore, a well hole, a micro hole, a slimhole, a perforation, or other term commonly used to define these types of long narrow passages. Wells would further include exploratory, production, abandoned, reentered, reworked, and injection wells. Although boreholes are generally oriented substantially vertically, they may also be oriented on an angle from vertical, to and including horizontal. Thus, using a vertical line, based upon a level as a reference point, a borehole can have orientations ranging from 0° i.e., vertical, to 90°, i.e., horizontal and greater than 90° e.g., such as a heel and toe and combinations of these such as for example “U” and “Y” shapes. Boreholes may further have segments or sections that have different orientations, they may have straight sections, arcuate sections, and combinations thereof; and for example, may be of the shapes commonly found when directional drilling is employed. Thus, as used herein unless expressly provided otherwise, the “bottom” of a borehole, the “bottom surface” of the borehole and similar terms refer to the end of the borehole, i.e., that portion of the borehole furthest along the path of the borehole from the borehole's opening, the surface of the earth, or theborehole's beginning. The terms “side” and “wall” of a borehole should be given their broadest possible meaning and include the longitudinal surfaces of the borehole, whether or not casing or a liner is present, as such, these terms would include the sides of an open borehole or the sides of the casing that has been positioned within a borehole. Boreholes may be made up of a single passage, multiple passages, connected passages, and combinations thereof. In a situation where multiple boreholes are connected or interconnected, each borehole would have a borehole bottom. Boreholes may be formed in the sea floor, under bodies of water, on land, in ice formations, or in other locations and settings.

[0090] As used herein, phrases of the form “at least one of an A, a B, or a C”, “at least one of A, B, or C”, “at least one of A, B, and C”, and similar phrases, should be interpreted to select at least one from the group that comprises A, B, and C. ^ Unless explicitly stated otherwise in connection with a particular instance, this manner of phrasing does not mean “at least one of A, at least one of B, and at least one of C.” ^ As used herein, the example “at least one of an A, a B, or a C” would cover any of the following selections: {A}, {B}, {C}, {A, B}, {A, C}, {B, C}, and {A, B, C}.

[0091] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense, i.e., in the sense of “including, but not limited to.” As used herein, the terms “connected,” “coupled,” or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words using the singular or plural number may also include the plural or singular number, respectively. The word “or” in reference to a list of two or more items, covers all of the following interpretations of the word: any one of the items in the list, all of the items in the list, and any combination of the items in the list. Likewise, the term “and / or” in reference to a list of two or more items,covers all of the following interpretations of the word: any one of the items in the list, all of the items in the list, and any combination of the items in the list. EXAMPLES

[0092] In view of the above-described implementations of subject matter this application discloses the following list of examples, wherein one feature of an example in isolation or more than one feature of an example, taken in combination and, optionally, in combination with one or more features of one or more further examples are further examples also falling within the disclosure of this application.

[0093] Example 1 is a method comprising: designing one or more underground pipelines for transmission of fluid based on an analysis of surrounding soil for the one or more underground pipelines; and installing the one or more underground pipelines, each of the one or more underground pipelines comprising one or more underground expansion loops and one or more anchor blocks, and the one or more underground expansion loops expanding against the surrounding soil to control thermal expansion movement during the transmission of the fluid.

[0094] In Example 2, the subject matter of Example 1 comprises wherein an underground expansion loop of an underground pipeline comprises two sections of the underground pipeline perpendicular to a direction of the underground pipeline and one section of the underground pipeline parallel to the direction of the underground pipeline.

[0095] In Example 3, the subject matter of Examples 1 – 2 comprises wherein the one or more underground expansion loops comprise a bend with a bend radius between 10D and 20D.

[0096] In Example 4, the subject matter of Examples 1 – 3 comprises wherein the one or more underground pipelines comprise a straight pipeline length between an anchor block and an underground expansion loop, the straight pipeline length between 328 feet and 3,280 feet.

[0097] In Example 5, the subject matter of Example 1 – 4 comprises wherein the one or more underground expansion loops comprise loopdimensions between 59 feet x 59 feet x 59 feet and 164 feet x 164 feet x 164 feet.

[0098] In Example 6, the subject matter of Examples 1 – 5 comprises wherein the one or more underground pipelines comprise pipeline material of material strength between 35 ksi and 70 ksi.

[0099] In Example 7, the subject matter of Example 1 – 6 comprises wherein the one or more underground expansion loops comprise wall thickness between 0.59 inches and 1.03 inches.

[0100] In Example 8, the subject matter of Example 1 – 7 wherein the one or more underground pipelines are installed at installation temperatures between 55 °F and 176 °F.

[0101] Example 9 is an enhanced geothermal system comprising: one or more underground pipelines for transmission of fluid, the one or more underground pipelines designed based on an analysis of surrounding soil for the one or more underground pipelines, each of the one or more underground pipelines comprising one or more underground expansion loops and one or more anchor blocks, and the one or more underground expansion loops expanding against the surrounding soil to control thermal expansion movement during the transmission of the fluid.

[0102] In Example 10, the subject matter of Example 9 comprises wherein an underground expansion loop of an underground pipeline comprises two sections of the underground pipeline perpendicular to a direction of the underground pipeline and one section of the underground pipeline parallel to the direction of the underground pipeline.

[0103] In Example 11, the subject matter of Examples 9 – 10 comprises wherein the one or more underground expansion loops comprise a bend with a bend radius between 10D and 20D.

[0104] In Example 12, the subject matter of Example 9 – 11 comprises wherein the one or more underground pipelines comprise a straight pipeline length between an anchor block and an underground expansion loop, the straight pipeline length between 328 feet and 3,280 feet.

[0105] In Example 13, the subject matter of Examples 9 – 12 comprises wherein the one or more underground expansion loops comprise loopdimensions between 59 feet x 59 feet x 59 feet and 164 feet x 164 feet x 164 feet.

[0106] In Example 14, the subject matter of Examples 9 – 13 comprises wherein the one or more underground pipelines comprise pipeline material of material strength between 35 ksi and 70 ksi.

[0107] In Example 15, the subject matter of Examples 9 – 14 comprises wherein the one or more underground expansion loops comprise wall thickness between 0.59 inches and 1.03 inches.

[0108] In Example 16, the subject matter of Examples 9 – 15 comprises wherein the one or more underground pipelines are installed at installation temperatures between 55 °F and 176 °F.

[0109] Example 17 is an underground pipeline for transmission of fluid, the underground pipeline comprising an underground expansion loop and an anchor block, and the underground expansion loop expanding against surrounding soil to control thermal expansion movement during the transmission of the fluid.

[0110] In Example 18, the subject matter of Example 17 comprises wherein the underground expansion loop comprises two sections of the underground pipeline perpendicular to a direction of the underground pipeline and one section of the underground pipeline parallel to the direction of the underground pipeline.

[0111] In Example 19, the subject matter of Examples 17 – 18 comprises wherein the underground expansion loop comprises a bend with a bend radius between 10D and 20D.

[0112] In Example 20, the subject matter of Examples 17 – 19 comprises a straight pipeline length between the anchor block and the underground expansion loop, the straight pipeline length between 328 feet and 3,280 feet.

[0113] Example 21 is a system to implement any of Examples 1 – 20.

[0114] Example 22 is a device or an apparatus to implement any of Examples 1 – 20.

[0115] Example 23 is a non-transitory, computer-readable medium including instructions that, when executed by processing circuitry, cause theprocessing circuitry to perform operations to implement any of Examples 1 – 20.

[0116] Example 24 is a method to implement any of Examples 1 – 20.

[0117] The present disclosure may be embodied in other forms than those specifically disclosed herein without departing from the essential characteristics of the present disclosure. The described examples are to be considered in all respects only as illustrative and not restrictive.

[0118] The various examples of systems, compositions, articles, uses, applications, equipment, methods, activities, and operations set forth in this specification may be used for various other fields and for various other activities, uses, and examples. Additionally, these examples may be used with: existing systems, compositions, articles, uses, applications, equipment, methods, activities, and operations; may be used with systems, compositions, articles, uses, applications, equipment, methods, activities, and operations that may be developed in the future; and with such systems, compositions, articles, uses, applications, equipment, methods, activities, and operations that may be modified, in-part, based on the teachings of this specification. Further, the various examples set forth in this specification may be used with each other, in whole or in part, and in different and various combinations. Thus, for example, the configurations provided in the various examples of this specification may be used with each other, and the scope of protection afforded by the present disclosure should not be limited to a particular example, configuration, or arrangement that is set forth in a particular example, or in an example in a particular figure.

Claims

CLAIMS What is claimed is:

1. A method comprising: designing one or more underground pipelines for transmission of fluid based on an analysis of surrounding soil for the one or more underground pipelines; and installing the one or more underground pipelines, each of the one or more underground pipelines comprising one or more underground expansion loops and one or more anchor blocks, and the one or more underground expansion loops expanding against the surrounding soil to control thermal expansion movement during the transmission of the fluid.

2. The method of claim 1, wherein an underground expansion loop of an underground pipeline comprises two sections of the underground pipeline perpendicular to a direction of the underground pipeline and one section of the underground pipeline parallel to the direction of the underground pipeline.

3. The method of claim 1, wherein the one or more underground expansion loops comprise a bend with a bend radius between 10D and 20D.

4. The method of claim 1, wherein the one or more underground pipelines comprise a straight pipeline length between an anchor block and an underground expansion loop, the straight pipeline length between 328 feet and 3,280 feet.

5. The method of claim 1, wherein the one or more underground expansion loops comprise loop dimensions between 59 feet x 59 feet x 59 feet and 164 feet x 164 feet x 164 feet.

6. The method of claim 1, wherein the one or more underground pipelines comprise pipeline material of material strength between 35 ksi and 70 ksi.

7. The method of claim 1, wherein the one or more underground expansion loops comprise wall thickness between 0.59 inches and 1.03 inches.

8. The method of claim 1, wherein the one or more underground pipelines are installed at installation temperatures between 55 °F and 176 °F.

9. An enhanced geothermal system comprising: one or more underground pipelines for transmission of fluid, the one or more underground pipelines designed based on an analysis of surrounding soil for the one or more underground pipelines, each of the one or more underground pipelines comprising one or more underground expansion loops and one or more anchor blocks, and the one or more underground expansion loops expanding against the surrounding soil to control thermal expansion movement during the transmission of the fluid.

10. The enhanced geothermal system of claim 9, wherein an underground expansion loop of an underground pipeline comprises two sections of the underground pipeline perpendicular to a direction of the underground pipeline and one section of the underground pipeline parallel to the direction of the underground pipeline.

11. The enhanced geothermal system of claim 9, wherein the one or more underground expansion loops comprise a bend with a bend radius between 10D and 20D.

12. The enhanced geothermal system of claim 9, wherein the one or more underground pipelines comprise a straight pipeline length between an anchor block and an underground expansion loop, the straight pipeline length between 328 feet and 3,280 feet.

13. The enhanced geothermal system of claim 9, wherein the one or more underground expansion loops comprise loop dimensions between 59 feet x 59 feet x 59 feet and 164 feet x 164 feet x 164 feet.

14. An underground pipeline for transmission of fluid, the underground pipeline comprising an underground expansion loop and an anchor block,and the underground expansion loop expanding against surrounding soil to control thermal expansion movement during the transmission of the fluid.

15. The underground pipeline of claim 14, wherein the underground expansion loop comprises two sections of the underground pipeline perpendicular to a direction of the underground pipeline and one section of the underground pipeline parallel to the direction of the underground pipeline.

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