Multi-layer permeable barrier layer for windable composite tube

Abstract

A rollable composite tube (100), a method for producing a rollable composite tube (100), and a method for transporting a hydrocarbon fluid are provided. A rollable composite tube (100) has an inner extruded tubular liner (101), a backing layer (105) surrounding the inner extruded tubular liner (101), and a reinforcement layer (109) surrounding the backing layer (105). The backing layer (105) comprises polypropylene and the inner extruded tubular liner comprises a thermoplastic. A method of production includes co-extruding an inner extruded tubular liner (101) with a backing layer (105), providing a reinforcement layer (109), and extruding a cover layer around the reinforcement layer (109). A method for transporting a hydrocarbon fluid includes providing a rollable composite tube (100) and introducing a hydrocarbon fluid having an aromatic content of up to about 35% by volume based on the total hydrocarbon content.

Description

BACKGROUND

[0001] Spoolable composite pipe can be used in fluid transport applications, including offshore oil and gas production, among others. After production, the spoolable composite pipe can be spooled on a reel and trucked to the site for installation. Spoolable composite pipe can include various products such as reinforced thermoplastic pipe (RTP), spoolable glass-reinforced epoxy pipe (s-GRE), or thermoplastic composite pipe (TCP). Generally, in RTP and s-GRE, the layers are unbonded or semi-bonded, while in TCP, all layers are melt-fused together to create a fully bonded structure. RTP and s-GRE are typically certified to API 15S standards, while TCP is typically certified to DNVGL-ST-F119.

[0002] Spoolable composite pipe can be used in water applications in the oil and gas industry. These types of pipes are increasingly being introduced into oil fields where there are high levels of water cut, as well as mixtures of hydrogen sulfide, carbon dioxide, and methane. Thus, there is a need for spoolable composite pipe that has sufficient mechanical properties, such as modulus and strength, when exposed to high aromatic components at high temperatures. SUMMARY

[0003] Certain embodiments of the disclosure will be described with reference to the drawings, in which like reference numerals refer to like elements throughout. The drawings, which are not necessarily to scale, depict various embodiments of the described technology.

[0004] In one aspect, embodiments herein relate to a spoolable composite pipe comprising: an inner extruded tubular liner, a backing layer surrounding the inner extruded tubular liner, and a reinforcement layer surrounding the backing layer. The backing layer comprises polypropylene, and the inner extruded tubular liner comprises a thermoplastic. The inner diameter of the inner extruded tubular liner is greater than 3.5 inches.

[0005] In another aspect, a method for producing a spoolable composite pipe is provided, the method comprising co-extruding a thermoplastic with a backing layer to form a spoolable composite pipe, providing a reinforcement layer on the backing layer, and extruding a cover layer around the reinforcement layer.

[0006] In still another aspect, a method for transporting a hydrocarbon fluid is provided, the method comprising providing a spoolable composite pipe, and introducing the hydrocarbon fluid into the spoolable composite pipe. The hydrocarbon fluid has an aromatic content of at most about 35% by volume based on total hydrocarbon content.

[0007] In yet another aspect, embodiments herein relate to an inner liner tube comprising an inner extruded tubular liner and a backing layer surrounding the inner extruded tubular liner. The backing layer comprises polypropylene and the inner extruded tubular liner comprises a thermoplastic. The inner liner tube is configured to operate at a temperature of at most 110 °C. The outer diameter of the backing layer is greater than 4 inches.

[0008] Other aspects and advantages of the present disclosure will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating the principles of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 A spoolable composite pipe is illustrated in accordance with one or more embodiments.

[0010] Figure 2A A cross-sectional view of an embodiment of a multi-layer system having two adjacent polymer layers is depicted.

[0011] Figure 2B A side view of an embodiment of a multi-layer system having two adjacent polymer layers is depicted.

[0012] Figure 3 Normalized permeability of a multi-layer inner tube system in accordance with one or more embodiments General plot of normalized permeability as a function of thickness ratio a.

[0013] Figure 4 Description of weight uptake (or weight gain) of different polymer materials exposed to aromatic hydrocarbon compositions at 93 °C and 1500 psig.

[0014] Figure 5 Description of length change of different polymer materials exposed to aromatic hydrocarbon compositions at 93 °C and 1500 psig.

[0015] Figure 6 Plot of tensile strength of virgin and conditioned polymer materials exposed to various environments.

[0016] Figure 7 Plot of maximum tensile stress of polymer materials exposed to various environments as a function of temperature.

[0017] Figure 8 Description of maximum strain values of virgin and conditioned polymer materials at 23 °C.

[0018] Figure 9 Description of maximum strain values of virgin and conditioned polymer materials at 82 °C and 93 °C.

[0019] Figure 10is a plot of permeability of different polymeric materials to several gases according to one or more embodiments.

[0020] Figure 11 is a plot of normalized permeability of different thermoplastics to polypropylene in a multi-layer inner pipe system according to one or more embodiments is a plot of permeability as a function of thickness ratio a. DETAILED DESCRIPTION

[0021] To improve the operating condition rating of spoolable composite pipes, various strategies have been employed. However, when used in oil & gas environments at high temperatures, thermoplastics such as polyethylene experience a reduction in mechanical properties such as modulus and strength due to material degradation, for example plasticization of the matrix, as a result of aromatic hydrocarbon absorption or swelling.

[0022] There is a need for spoolable composite pipes capable of transporting fluids, such as can be used in the oil and gas industry, while maintaining desirable physical and mechanical properties when exposed to higher temperatures, high aromatic content, and acidic environments.

[0023] Provided are pipes and methods of making the same that use a thermoplastic in the liner material of a spoolable composite pipe and polypropylene in the backing layer to provide a pipe capable of operating at temperatures up to 110°C and transporting hydrocarbons with an aromatic hydrocarbon content of up to 35% by volume based on the total hydrocarbon content, particularly for oil and gas flowline applications. The thermoplastic can be an engineering thermoplastic or a high performance thermoplastic known in the art.

[0024] In one or more embodiments, spoolable composite pipes are provided. These pipes can include an inner extruded tubular liner, a backing layer surrounding the inner extruded tubular liner, and a reinforcement layer surrounding the backing layer. The backing layer can be co-extruded with the inner extruded tubular liner. The inner extruded tubular liner can contain an engineering or high performance thermoplastic. Such spoolable composite pipes can be configured to operate at temperatures up to 110°C and transport hydrocarbons with an aromatic hydrocarbon content of up to 35% by volume based on the total hydrocarbon content.

[0025] The inner extruded tubular liner acts as a permeation barrier for different gases that can be encountered in oil and gas production, such as hydrogen sulfide (H2S), carbon dioxide (CO2), and methane (CH4). The inner extruded tubular liner can also act as a permeation barrier for liquid aromatic hydrocarbons from permeating into the backing material to reduce swelling and degradation of the backing material. The engineering or high performance thermoplastic having a low permeability to one or more of H2S, CO2, CH4, and liquid aromatic hydrocarbons is used to reduce the amount of gas reaching the backing layer that can potentially reduce its performance.

[0026] Figure 1A spoolable composite pipe 100 is illustrated in accordance with one or more embodiments. The spoolable composite pipe 100 includes an inner extruded tubular liner 101, a backing layer 105 surrounding the inner extruded tubular liner 101, and a reinforcing layer 109 surrounding the backing layer 105. The spoolable composite pipe 100 can optionally include a bonding or adhesive layer 103 between the inner extruded tubular liner 101 and the backing layer 105. In addition, the spoolable composite pipe 100 can optionally include a bonding or adhesive layer 107 between the backing layer 105 and the reinforcing layer 109. A multi-layer inner pipe system 111 includes the inner extruded tubular liner 101, the backing layer 105, and the optional bonding or adhesive layer 103.

[0027] The use of thermoplastics as cost-effective liner materials or fluid permeation barrier layers for pipes for oil and gas flow lines for operating at high temperatures, such as up to 105°C, up to 110°C, or in a range of a lower temperature limit of 80°C, 85°C, or 90°C up to an upper temperature limit of 105°C or 110°C, for transporting crude oil fluids having a high aromatic and alicyclic hydrocarbon content, such as up to 50% by volume based on total hydrocarbon content, and where the aromatic content can be up to 35% by volume based on total hydrocarbon content. The environment of these composite pipes can be a sweet (or low sulfur) environment with limited hydrogen sulfide (H2S), or an acidic environment with a H2S partial pressure of up to 10 bar gauge (barg). Thus, the inner extruded tubular liner can contain a thermoplastic.

[0028] In some embodiments, the thermoplastic includes a semi-crystalline polymer. In one or more embodiments, the thermoplastic can include one or more of polyvinylidene fluoride (PVDF), polyphenylene sulfide (PPS), polyamide (PA), or aliphatic polyketone (POK). The thermoplastic can also include one or more other semi-crystalline thermoplastics, such as those in the family of polyaryletherketones, including but not limited to polyetherketone (PEK), polyether ether ketone (PEEK), polyetherketone (PEKK), and blends thereof.

[0029] In some embodiments, the inner extruded tubular liner can be a standalone thermoplastic extruded pipe as a single layer system, or the thermoplastic can be co-extruded with other thermoplastic polymers as a multi-layer system. For example, the liner can include a thin layer of thermoplastic as defined above, which can be the innermost layer in contact with the hydrocarbons in the crude oil fluid. An optional additional layer, which can be thicker than the inner layer of the inner extruded tubular liner, can be of the same material, or the optional additional layer can include other thermoplastics or metals, such as, for example, aluminum. An additional bonding layer can be used to bond the optional additional layer to other layers of the inner extruded tubular liner.

[0030] In one or more embodiments, the inner extruded tubular liner can have an inner diameter greater than 3.5 inches (8.89 cm), greater than 4.0 inches (10.16 cm), greater than 5.0 inches (12.7 cm), or greater than 6.0 inches (15.24 cm), and can be less than 15 inches (38.1 cm), less than 12 inches (30.48 cm), or less than 10 inches (25.4 cm).

[0031] The inner extruded tubular liner material acts as a permeation barrier and comprises a thermoplastic with very low permeability to CH4, H2S, and CO2. In addition, the liner material has high mechanical strength and is resistant to bending and stretching. Furthermore, the pipe with the liner material or fluid permeation barrier according to one or more embodiments has chemical resistance and can swell less when in contact with hydrocarbons than some conventional liner materials. The inner extruded tubular liner contacts the fluid within the pipe and, through its resistance to swelling and low permeability to various components, can be used to reduce the migration of CH4, H2S, and CO2or hydrocarbons to the subsequent outer layers of the pipe.

[0032] In one or more embodiments, the inner extruded tubular liner can have a thickness in a range of a minimum of any one of 0.3 mm, 0.4 mm, 0.5 mm, or 0.6 mm and a maximum of any one of 1.5 mm, 1.3 mm, 1.2 mm, or 1.0 mm.

[0033] A tie layer can be included around the inner extruded tubular liner. The tie layer allows the inner extruded tubular liner to chemically bond with surrounding layers during the co-extrusion process. This material of the tie layer can be selected to adhere the inner extruded tubular liner to other outer layers. In one or more embodiments, the tie layer can have a thickness in a range of a minimum of any one of 50 pm, 70 pm, 80 pm, 100 pm, 120 pm, or 150 pm and a maximum of any one of 150 pm, 175 pm, 200 pm, 225 pm, 250 pm, 275 pm, or 300 pm.

[0034] A backing layer is located around the inner extruded tubular liner and comprises polypropylene (PP). The backing layer can be significantly thicker than the inner extruded tubular liner as it is designed as the main component in the multi-layered structure to withstand the loads experienced by the multi-layered inner pipe system during operation.

[0035] The backing layer can comprise homopolymer PP or copolymer PP. The PP can be syndiotactic, atactic, isotactic, eutactic, or a combination of these.

[0036] Polypropylene can be used in one or more embodiments because it can maintain a high maximum allowable operating temperature defined by mechanical properties as well as a high tensile strength even when exposed to hydrocarbons at elevated temperatures and pressures. In one or more embodiments, the use of polypropylene can also provide ease of manufacture, in part due to its low melting point, which can be in the range of 125°C to 175°C.

[0037] Since the inner extruded tubular liner acts as a permeation barrier to prevent gas migration and protect the backing layer, the thickness ratio between the inner extruded tubular liner and the backing layer can be obtained by the following equation.

[0038] Figure 2A and 2B A multilayer system 200 having two adjacent polymer layers is depicted in accordance with one or more embodiments. Figure 2A A cross-sectional view of the multilayer system 200 is shown, while Figure 2B A side view of the multilayer system 200 is shown. In Figure 2A and Figure 2B The two adjacent polymer layers 201 and 205 are shown in FIGS. 1 and 2. Layer 201 corresponds to the inner extruded tubular liner previously described, and layer 205 corresponds to the backing layer. Figure 2A and Figure 2B The effective permeability of the multilayer system of FIGS. 1 and 2 to gas i can be expressed by equation 1.

[0039] (1)

[0040] Here, K eq_i is the effective permeability of gas i through the multilayer system, hi and h2 are the thicknesses of polymer layers 201 and 205, respectively, h is the combined thickness of the two layers, and K 1i and K 2i are the permeability coefficients of gas i through polymer layers 201 and 205, respectively. Equation 1 can be simplified by defining the quantity a as the following equation:

[0041] (2)

[0042] The quantity a defined in equation 2 above is the ratio of the thickness of polymer layer 201 to the sum of the thicknesses of polymer layers 201 and 205.

[0043] Equation 1 can be simplified to

[0044] (3)

[0045] where K r is the ratio of the permeability of polymer layer 205 to the permeability of polymer layer 201.

[0046] Figure 3Normalized permeability of a multi-layer inner pipe system according to one or more embodiments General plot as a function of thickness ratio a. In one or more embodiments, the permeability ratio K r of the permeation barrier layer requires a minimum thickness ratio a of about 15%. This results in a reduction of the H2S permeability of more than 80% when compared to pure PP. In one or more embodiments, the value of K r can be at least 30 and can be in the range between 30 and 200. The permeability ratio can be in the range of a maximum of any one of 200, 170, 150, and 100 and a minimum of any one of 30, 40, 50, 60, 70, 80, and 90.

[0047] The thickness ratio a or the ratio of the thickness of the inner extruded tubular liner to the thickness of the backing layer plus the thickness of the inner extruded tubular liner is defined by equation 2 above. The thickness ratio a can be in the range between 4% and 25%. In one or more embodiments, the thickness ratio a can be in the range of a maximum of any one of 25%, 22%, 20%, 18%, 15%, 13%, 12%, 10%, or 9% and a minimum of any one of 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, and 15%, where any maximum can be paired with any mathematically compatible minimum. In some embodiments, the thickness from the inside of the inner extruded tubular liner to the outside of the backing layer can be in the range of a minimum of any one of 2 mm, 4 mm, 5 mm, and 7 mm and a maximum of any one of 25 mm, 22 mm, 20 mm, 15 mm, and 10 mm.

[0048] The spoolable composite pipe can include an inner extruded tubular liner and a pipe comprising polypropylene as a backing layer surrounding the inner extruded tubular liner. The inner extruded tubular liner can comprise a thermoplastic. Such an inner liner pipe can be configured to operate at temperatures of at most 105°C or 110°C and transport hydrocarbons with an aromatic content of at most 35% by volume based on the total hydrocarbon content.

[0049] In some embodiments, there can be a reinforcement layer surrounding the backing layer. The reinforcement layer can comprise dry glass fibers, aramid fibers, carbon fibers, steel fibers or steel strips, glass reinforced epoxy laminate or unidirectional thermoplastic composite tape. In some embodiments, the reinforcement layer can comprise a polyolefin, an engineering thermoplastic, or a thermoplastic polyester.

[0050] A bonding layer can be included around the backing layer. The bonding layer allows the backing layer to chemically bond with surrounding layers. Such a material of the bonding layer can be selected to adhere the backing layer to an outer layer, such as a reinforcement layer.

[0051] In one or more embodiments, a cover layer may be present around the reinforcing layer. An adhesive layer may be present between the cover layer and the reinforcing layer to attach the cover layer to the reinforcing layer. The cover layer may comprise a polymer or other material and may be extruded around the reinforcing layer. The production of the windable composite tube may be a continuous process, which may be performed by co-extruding an inner extruded tubular liner and backing layer, moving the inner extruded tubular liner and backing layer to a winding station to place and reinforce the reinforcing layer, and extruding a cover layer around the reinforcing layer.

[0052] The construction of a rollable composite tube can be unbonded, semi-bonded, or fully bonded, meaning that the layers are not fused, partially fused, or fully fused together via a heating process. In particular, thermoplastics can be used as part of a fully bonded construction, where the backing layer (if thermoplastic-based) can be fully fused to the liner tube via a heating process. In one or more embodiments, the internally extruded tubular liner and backing layer can also be co-extruded. Alternatively, an adhesive layer or bonding layer can be used between the liner and backing layer and / or between the backing layer and the overlay layer.

[0053] In some embodiments, the spiral-wound composite tube can be used to transport hot, acidic, wet hydrocarbons. The spiral-wound composite tube can be configured to operate in a desulfurized (with limited or no hydrogen sulfide) or acidic (with a hydrogen sulfide partial pressure of up to 10 bar gauge pressure) wet gas environment or a dry gas environment. In this context, dry gas refers to natural gas containing more than 85% methane, while wet gas refers to natural gas containing less than 85% methane. When exposed to a dry gas environment containing hydrogen sulfide, carbon dioxide, and methane (such as, for example, 10% hydrogen sulfide, 10% carbon dioxide, and 80% methane), the spiral-wound composite tube can have a lower... The permeability is high. The internally extruded tubular liner prevents backing layer swelling while maintaining sufficient mechanical properties after exposure to hydrocarbons. Specifically, in some embodiments, the wound composite tube maintains the required mechanical properties after exposure to highly aromatic hydrocarbons (35% to 50% by volume of aromatic hydrocarbons based on the total volume of hydrocarbons) at temperatures up to 110°C or between 90°C and 110°C, while also providing sufficient barrier properties against the permeation of harmful gases such as H2S and CO2. Furthermore, modulus retention prevents liner collapse under rapid gas decompression. It should be noted that preventing liner collapse typically involves using a ventilation system where permeated gas is allowed to diffuse horizontally along the liner to the tube connector and then reinjected into the conveyed stream.

[0054] In some embodiments, the present disclosure relates to a method for producing a spoolable composite pipe for oil and gas flow lines as described above. The method can include extruding a thermoplastic to form an inner tubular liner; forming a backing layer on the inner extruded tubular liner to form a spoolable composite pipe; and providing a reinforcement layer on the backing layer.

[0055] In one or more embodiments, the inner extruded tubular liner and the backing layer can be co-extruded to form the spoolable composite pipe.

[0056] In one or more embodiments, a method for transporting a hydrocarbon fluid can be provided. The hydrocarbon fluid can be introduced into the spoolable composite pipe. The hydrocarbon fluid can have an aromatic content of at most about 35% by volume based on total hydrocarbon content. In one or more embodiments, the hydrocarbon fluid can have an aromatic and naphthenic content of at most about 50% by volume based on total hydrocarbon content. The hydrocarbon fluid can be at a temperature in a range having a lower limit of any of 80°C, 85°C, or 90°C and an upper limit of 105°C or 110°C. The hydrocarbon fluid can be in a dry gas environment having a hydrogen sulfide partial pressure of at most 10 bar gauge.

[0057] For static applications without cyclic fatigue, the maximum temperature rating can be determined by the temperature rating of the material of the inner extruded tubular liner in a particular environment of interest, as determined via performance-based testing. A lower temperature rating can be determined by a decrease in impact resistance at low temperatures.

[0058] In some embodiments, the present disclosure relates to a method for transporting a hydrocarbon fluid having an aromatic content of at most 35% by volume based on total hydrocarbon content. The method can include providing a spoolable composite pipe for oil and gas flow lines as described above, and introducing the hydrocarbon fluid into the spoolable composite pipe. The method can optionally include providing an inner liner pipe for oil and gas flow lines as described above, and introducing the hydrocarbon fluid into the inner liner pipe.

[0059] Examples

[0060] Polymer aging test protocol was conducted according to ISO 23936 protocol, but with custom hydrocarbon components. Tensile test specimens (ISO 527 1BA) were immersed in an autoclave to expose them to hydrocarbon components rich in specific aromatics shown in Table 1 at 93°C and 1500 psig. The polypropylene was aged for a total period of 90 days, taken out every 15 days, and weight uptake and length measurements were performed. After full saturation, the polymer was removed from the autoclave and immediately tested for tensile modulus / strength according to ISO 527 at different temperatures. PE-RT as a comparative example (XRT-70 provided by TotalEnergies) was exposed to the same treatment and testing. The values obtained were then compared to those measured on the original (as received) polymer and benchmarked against those measured on PE-RT.

[0061] Table 1: Composition of the hydrocarbon environments with high aromatics content used in the aging test.

[0062]

[0063] Here, IRM 902 is a test oil produced by R.E. Carroll Company and refers to a heavy hydrotreated naphthenic distillate.

[0064] Figure 4 is a description of the weight uptake of different example materials exposed to aromatic hydrocarbon compositions at 93°C and 1500 psi according to one or more embodiments. In particular, PP was exposed to the conditions of Table 1 and PE-RT as a comparative example was exposed to the same conditions. Over the length of the experiment, similar weight uptake was observed for both polymers.

[0065] Figure 5 is a description of the length change of different example materials exposed to aromatic hydrocarbon compositions at 93°C and 1500 psi according to one or more embodiments. PP was exposed to the conditions of Table 1 and PE-RT as a comparative example was exposed to the same conditions. Over the length of the experiment, PP had a greater length increase than PE-RT. Generally, high degree of swelling in polyolefins can indicate enhanced plasticization of the matrix and loss of mechanical properties.

[0066] The tested physical properties of PE-RT (CE1) and PP (E1) are provided in Tables 2 and 3.

[0067] Table 2: Properties of the original polymers

[0068]

[0069] Table 3: Properties of the aged polymers

[0070]

[0071] In Figure 6 and Figure 7 The results in Tables 2 and 3 are provided. Figure 6 is a plot of the tensile strength of virgin and treated polymeric materials exposed to various environments. Figure 7 is a plot of the maximum tensile stress of virgin and treated polymeric materials exposed to various environments. As seen in Figure 6 and Figure 7 Temperature causes the tensile strength of PE-RT and PP to decrease exponentially, as seen in Figure 5 Exposure to aromatic hydrocarbons at high temperatures causes swelling of both polymers, which further decreases the tensile modulus and strength of both polymers when compared to the properties retained in the virgin polymers, as seen in

[0072] Figure 8 is a depiction of the maximum strain values of virgin and treated polymeric materials at 23 °C. Figure 8 is a depiction of the maximum strain values of virgin and treated polymeric materials of PE-RT and PP at 82 °C and 93 °C, respectively. Figure 8 and Figure 9 The results in Tables 2 and 3 are provided.

[0073] Figure 10 is a plot of the permeability of several polymeric materials to several gases according to one or more embodiments. Polypropylene shows lower methane permeability, comparable carbon dioxide permeability, and higher H2S permeability than PE-RT.

[0074] Table 4 provides a summary of the order of magnitude of various permeability ratios of polypropylene and several thermoplastic materials under different gases according to one or more embodiments.

[0075] Table 4: Permeability ratio K of different multilayer structures r These values represent orders of magnitude (qualitative basis).

[0076]

[0077] Figure 11 Normalized permeability of different thermoplastics to polypropylene in a multilayer inner pipe system according to one or more embodiments Graph as a function of thickness ratio a. As seen in Table 4 and Figure 11 The PPS-PP system in this example shows better performance in reducing permeability for a given thickness ratio, as seen in Table 4 and Figure 11 The PPS-PP system in this example shows better performance in reducing permeability for a given thickness ratio, as seen in Table 4 and r A permeation barrier layer with a value of 30 requires a minimum thickness ratio of about 15% (i.e. about 1 mm of thermoplastic on a total inner extruded tubular liner and backing layer thickness of 7 mm), resulting in a reduction of H2S permeability through the inner extruded tubular liner and backing layer of more than 80% when compared to pure polypropylene as a benchmark.

[0078] While only a limited number of embodiments have been described, those skilled in the art having the benefit of this disclosure will appreciate that other embodiments, not expressly described, can be devised without departing from the scope of the disclosure.

[0079] Although the foregoing description has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein; rather, it extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.

[0080] The presently disclosed methods and compositions can suitably comprise, consist of, or consist essentially of the disclosed elements, and can be implemented without the use of the disclosed elements. For example, one of skill in the art can appreciate that certain steps can be combined into a single step.

[0081] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which these systems, apparatuses, methods, processes and compositions belong.

[0082] The scope of the disclosure can be expressed herein as from about one particular value to about another particular value, or both. When expressing such a range, it is to be understood that another embodiment is from one particular value to the other particular value, or both, and all combinations within the range.

[0083] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0084] As used herein and in the appended claims, the words "comprise," "has," and "include" and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not preclude the addition of more elements or steps.

[0085] "Optionally" or "optional" means that the subsequently described event or circumstance can or cannot occur. Descriptions which include events or circumstances which

[0086] When the word "about" or "approximately" is used, the term can mean that the value in question can be up to ±10%, up to 5%, up to 2%, up to 1%, up to 0.5%, up to 0.1%, or up to 0.01%.

[0087] Ranges can be expressed as from about one particular value to about another; however, another embodiment is from the one particular value to the other particular value, inclusive. When such ranges are expressed, it is to be understood that another embodiment is from the one particular value to the other particular value, along with all the intervening values and combinations thereof.

[0088] While only several exemplary embodiments have been described in detail, those skilled in the art will readily comprehend numerous modifications. Thus, all such modifications are intended to be included within the scope of the present disclosure as defined in the following claims.

Claims

1. A spoolable composite pipe comprising: an inner extruded tubular liner; a backing layer surrounding the inner extruded tubular liner; and a reinforcing layer surrounding the backing layer, wherein the backing layer comprises polypropylene; wherein the inner extruded tubular liner comprises a thermoplastic; and wherein the inner diameter of the inner extruded tubular liner is greater than 3.5 inches.

2. The spoolable composite pipe of claim 1, wherein the thermoplastic is selected from the group consisting of polyvinylidene fluoride, polyphenylene sulfide, polyketone, and polyamide.

3. The spoolable composite pipe of claim 1 or claim 2, further comprising a cover layer surrounding the reinforcing layer.

4. The spoolable composite pipe of any one of claims 1 to 3, wherein the ratio of the thickness of the inner extruded tubular liner to the sum of the thickness of the inner extruded tubular liner and the thickness of the backing layer is in the range of 4% to 25%.

5. The spoolable composite pipe of any one of claims 1 to 4, wherein the thickness from the inside of the inner extruded tubular liner to the outside of the backing layer is in the range of 2 mm to 25 mm.

6. The spoolable composite pipe of any one of claims 1 to 5, wherein the thermoplastic and the polypropylene have a permeability ratio of at least 30.

7. The spoolable composite pipe of any one of claims 1 to 6, wherein the inner extruded tubular liner is a single layer extruded tube.

8. The spoolable composite pipe of any one of claims 1 to 7, further comprising an adhesive layer between the inner extruded tubular liner and the backing layer.

9. The spoolable composite pipe of any one of claims 1 to 8, wherein the inner extruded tubular liner and the backing layer are co-extruded.

10. The spoolable composite pipe of any one of claims 1 to 9, wherein the spoolable composite pipe is non-adhered, semi-adhered, or adhered.

11. The spoolable composite pipe of any one of claims 1 to 10, wherein the reinforcing layer comprises a material selected from the group consisting of dry glass fibers, aramid fibers, carbon fibers, steel fibers or steel strips, glass reinforced epoxy laminate, unidirectional thermoplastic composite tape, and combinations thereof.

12. The spoolable composite pipe of any one of claims 1 to 11, further comprising an adhesive layer between the backing layer and the reinforcing layer.

13. The spoolable composite pipe of claim 3, further comprising an adhesive layer between the reinforcing layer and the cover layer.

14. A method for producing a spoolable composite pipe for oil and gas flow lines according to claim 3, the method comprising: co-extruding a thermoplastic with a backing layer on an inner extruded tubular liner to form the spoolable composite pipe; providing a reinforcing layer on the backing layer; and extruding a cover layer around the reinforcing layer.

15. A method for transporting a hydrocarbon fluid, the method comprising: providing a spoolable composite pipe according to claim 1; and introducing the hydrocarbon fluid into the spoolable composite pipe, wherein the hydrocarbon fluid has an aromatic content of at most about 35% by volume based on total hydrocarbon content.

16. The method of claim 15, wherein the hydrocarbon fluid has at most about 50 vol% aromatics and naphthenes content based on total hydrocarbon content.

17. The method of claim 15 or claim 16, wherein the hydrocarbon fluid is a dry gas environment having a hydrogen sulfide partial pressure of at most 10 bar gauge.

18. The method of any one of claims 15 to 17, wherein the hydrocarbon fluid is at a temperature in the range of 80 °C to 110 °C.

19. An inner liner tube comprising: an inner extruded tubular liner; and a backing layer surrounding the inner extruded tubular liner, wherein the inner liner tube is configured to operate at a temperature of at most 110 °C, wherein the backing layer comprises polypropylene; wherein the inner extruded tubular liner comprises a thermoplastic, and wherein the backing layer has an outer diameter of greater than 4 inches.

20. The inner liner tube of claim 19, wherein the ratio of the permeability of the backing layer to the permeability of the inner extruded tubular liner is greater than 30.

21. The inner liner tube of claim 19 or claim 20, configured to operate in a dry gas environment having a hydrogen sulfide partial pressure of at most 10 bar gauge. ​

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