CA2676337C - Non-phosphorus hydrocarbon gelling system - Google Patents
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Abstract
The present application is directed to a non-phosphorus hydrocarbon gelling system for use in preparing gelled hydrocarbon fracturing fluids. The non-phosphorus hydrocarbon gelling system comprises a flowable fluid gellant, an accelerator, an enhancer, a breaker or breaker-containing slurry and optionally a surfactant. The flowable fluid gellant contains an aluminum salt of a fatty acid and a polar fluid.
Description
NON-PHOSPHORUS HYDROCARBON GELLING SYSTEM
Field [0001 ] The present application relates to a gelling system for forming a hydrocarbon gel that is totally free of phosphorus based compounds.
Background [0002] Hydrocarbon gels are used in a variety of applications in the oil, chemical and related industries, including fracturing fluids to improve the recovery of oil and natural gas from subterranean formations. The fracturing fluid is pumped into the formation at a rate sufficient to open a fracture, and usually contains particles of a propping agent which remain in the fractures, preventing the fractures from closing and providing a channel through which the oil and natural gas can be recovered. Gelled hydrocarbon fluids have sufficient viscosity to suspend the propping agents and to provide the necessary hydraulic pressure to open the fractures.
Field [0001 ] The present application relates to a gelling system for forming a hydrocarbon gel that is totally free of phosphorus based compounds.
Background [0002] Hydrocarbon gels are used in a variety of applications in the oil, chemical and related industries, including fracturing fluids to improve the recovery of oil and natural gas from subterranean formations. The fracturing fluid is pumped into the formation at a rate sufficient to open a fracture, and usually contains particles of a propping agent which remain in the fractures, preventing the fractures from closing and providing a channel through which the oil and natural gas can be recovered. Gelled hydrocarbon fluids have sufficient viscosity to suspend the propping agents and to provide the necessary hydraulic pressure to open the fractures.
[0003] In the past, hydrocarbon gelling systems were based on aluminum salts of fatty acids.
One problem observed with these gelling systems was the failure to generate adequate viscosity within the time allotment at the fracture site. Those systems have been replaced over time by systems based on phosphorus components. Currently, service companies primarily use cross-linked phosphate esters for their hydrocarbon gelling systems.
One problem observed with these gelling systems was the failure to generate adequate viscosity within the time allotment at the fracture site. Those systems have been replaced over time by systems based on phosphorus components. Currently, service companies primarily use cross-linked phosphate esters for their hydrocarbon gelling systems.
[0004] However, in the last ten years, tower fouling has been an ongoing concern for refineries.
Tower fouling incidents are associated with the presence of volatile phosphorus in distilled fractions. One possible solution for reducing phosphorus content in crude oil is the use of a non-phosphorus hydrocarbon gelling system.
Summary [0005] One aspect of the present application is directed to a non-phosphorus hydrocarbon gelling system (NPHG-S) comprising a flowable fluid gellant which comprises an aluminum salt of a fatty acid and a polar fluid. Other components of the non-phosphorus hydrocarbon gelling system include an accelerator, an enhancer, a breaker, and optionally a surfactant.
Tower fouling incidents are associated with the presence of volatile phosphorus in distilled fractions. One possible solution for reducing phosphorus content in crude oil is the use of a non-phosphorus hydrocarbon gelling system.
Summary [0005] One aspect of the present application is directed to a non-phosphorus hydrocarbon gelling system (NPHG-S) comprising a flowable fluid gellant which comprises an aluminum salt of a fatty acid and a polar fluid. Other components of the non-phosphorus hydrocarbon gelling system include an accelerator, an enhancer, a breaker, and optionally a surfactant.
[0006] A further aspect of the present application is directed to a flowable fluid gellant which comprises an aluminum salt of a fatty acid and a polar fluid.
[0007] In another aspect, the present application is directed to a method of preparing a hydrocarbon fracturing fluid comprising adding the non-phosphorus hydrocarbon gelling system to a hydrocarbon fluid.
[0008] In a further aspect, the present application is directed to a hydrocarbon fracturing fluid prepared by adding the non-phosphorus hydrocarbon gelling system to a hydrocarbon fluid.
Brief Description of the Drawings [0009] Specific embodiments of the present non-phosphorus hydrocarbon gelling system are now described in greater detail and can be better understood by the skilled person when read in conjunction with the drawings in which:
Brief Description of the Drawings [0009] Specific embodiments of the present non-phosphorus hydrocarbon gelling system are now described in greater detail and can be better understood by the skilled person when read in conjunction with the drawings in which:
[0010] Figure 1 is a plot of viscosity and temperature against time for one embodiment of a hydrocarbon fracturing fluid prepared using the present non-phosphorus hydrocarbon gelling system;
[0011 ] Figure 2 is a plot of viscosity and n' (the power law exponent from viscosity power law equations) against time for the embodiment of Figure 1;
[0012] Figure 3 is a comparative plot of n' against time for embodiments of hydrocarbon fracturing fluids prepared using the present non-phosphorus hydrocarbon gelling system containing different concentrations of flowable fluid gellant;
[0013] Figure 4 is a comparative plot of viscosity against time for the embodiments of Figure 3;
[0014] Figure 5 is a comparative plot of n' against time for embodiments of hydrocarbon fracturing fluids prepared in Diesel P40 using the present non-phosphorus hydrocarbon gelling system containing different breaker-containing slurries;
[0015] Figure 6 is a comparative plot of viscosity against time for the embodiments of Figure 5;
[0016] Figure 7 is a comparative plot of n' against time for embodiments of hydrocarbon fracturing fluids prepared in TSO 9001 using the present non-phosphorus hydrocarbon gelling system containing different breaker-containing slurries; and [0017] Figure 8 is a comparative plot of viscosity against time for the embodiments of Figure 7.
Detailed Description [0018] In at least one embodiment, the present non-phosphorus hydrocarbon gelling system comprises a flowable fluid gellant; an accelerator; an enhancer; a breaker or a breaker-containing slurry; and optionally a surfactant. The non-phosphorus hydrocarbon gelling system is mixed with a base hydrocarbon fluid, including but not limited to Diesel P40 and TSO 9001, so as to form a gel which can be used as a hydrocarbon fracturing fluid. In at least one embodiment, the non-phosphorus hydrocarbon gelling system is added to the hydrocarbon fluid so that the mixture contains about 0.5% to about 3.0% (v/v) of a flowable fluid gellant, about 0.1% to about 0.5% (v/v) of an accelerator, about 0.01% to about 0.1% (v/v) of an enhancer, about 0.01 kg/m3 to about 0.2 kg/m3 of a breaker or about 0.05% to about 0.5%
(v/v) of a breaker-containing slurry and optionally about 0.05% to about 0.2% (v/v) of surfactant. In at least one embodiment, the components of the non-phosphorus hydrocarbon gelling system are blended with the base hydrocarbon fluid using a standard blender equipped with a 3-blade or a 4-blade propeller stirrer, following procedures well known in the art.
[0019] In at least one embodiment, such a system advantageously meets one or more of the following criteria:
= shows well known signs of developing gel formation, including but not limited to gel vortex closure, within 2 minutes or less of blending the system with hydrocarbon fluid;
= has a minimum initial viscosity of about 100 cP or higher at about 100 sec';
= has a peak viscosity of about 100 cP to about 1300 cP at about 100 sec', at a temperature of about 50 C to about 90 C;
= has an adjustable gel strength lifetime wherein a viscosity of at least about 100 cP at about 100 sec' is maintained for at least about 20 minutes, and advantageously from about 40 minutes to about 120 minutes;
= shows non-Newtonian visco-elastic properties with a value of n' (the power law exponent from viscosity power law equations) of no more than about 0.5 for at least about 20 minutes;
maintains viscosity properties independently of the temperature, pressure and shear stress; and = should "break" after about 30 minutes, so as to reduce the viscosity to no higher than about 15 cP at about 100 sec'.
Such criteria are measured using procedures which are well known in the art.
[0020] It can be seen from Figures 1, 2, 4, 6 and 8 that the initial viscosity of a hydrocarbon fracturing fluid prepared using the present non-phosphorus hydrocarbon gelling system increases exponentially and very rapidly. Such a rapid initial viscosity increase is a property of the present non-phosphorus hydrocarbon gelling system which strengthens under exposure to shear and temperature stress.
[0021] In at least one embodiment, the flowable fluid gellant comprises an aluminum salt of a fatty acid and a polar fluid. The flowable fluid gellant is a stable fluid which is easy to handle and pump, in contrast to pure aluminum salts of fatty acids, which are generally in a solid powder form. Suitable aluminum salts of fatty acids include, but are not limited to, aluminum 2-ethylhexanoate (aluminum octoate, including but not limited to CALFORDTM
G760). The polar fluid can be any suitable polar fluid known in the art, including but not limited to water, alcohols, ketones, alkylene carbonates, and esters. In at least one embodiment, the polar fluid is propylene carbonate (for example, JeffsolTM PC). In at least one embodiment, the flowable fluid gellant contains up to 70% by weight of aluminum 2-ethylhexanoate in propylene carbonate.
The flowable fluid gellant is advantageously prepared by adding the aluminum salt of the fatty acid to the polar fluid, while blending the mixture with a blender equipped with a 3-blade or a 4-blade propeller stirrer.
[0022] Without being bound by theory, it is believed that the polar fluid acts as a carrier for the aluminum salt of a fatty acid, so as to provide a fluid, easy to handle formulation. In at least one embodiment, the polar fluid also acts as a latent cross-linking agent which can react with the fatty acid aluminum salt, in the presence of the accelerator, to form a web-like network which aids in the gelling process. It is further believed that the accelerator acts to decrease the time needed for the initial gel formation by facilitating this cross-linking reaction. Suitable accelerators include but are not limited to a rosin-modified phenolic resin, including but not limited to RAYBOTM 77 (Raybo Chemical Company).
[0023] The enhancer acts to stabilize the gel so as to maintain a suitable gel strength lifetime, by allowing the gel to develop a stronger micro-viscosity under shear and temperature stress.
Without being bound by theory, it is believed that the enhancer acts to produce a more convoluted cross-linked network. Suitable enhancers include but are not limited to a high rosin acid modified phenolic ester resin or a blend of a rosin-modified phenolic resin with dimerised fatty acids. In at least one embodiment, the enhancer is selected from SI-191-103/30T (Arizona Chemicals), SI-237-119/30T (Arizona Chemicals), and a mixture of RAYBOTM 77 (Raybo Chemical Company) and Unidyme 41 (Arizona Chemicals).
[0024] The breaker acts to allow the viscosity of the system to decrease once the system has fulfilled its purpose as a fracturing fluid, so that the spent fluid can be easily retrieved, or allowed to leak away into the surrounding formation, leaving the propping agent behind in the fracture channel. Suitable breakers include alkaline earth metal oxides, including but not limited to magnesium oxide and calcium oxide. In at least one embodiment, the breaker is hard burned magnesium oxide 10CR.
[0025] The breaker can advantageously be mixed with other materials to form a slurry prior to being added to other components of the non-phosphorus hydrocarbon gelling system. Suitable additional ingredients of such a breaker-containing slurry include but are not limited to a drilling fluid, including but not limited to a mineral oil drilling fluid (for example, PureDrillTM HT40), a gelling agent, including but not limited to a clay gelling agent (for example BENTONETM 150), an activator for the clay gelling agent including but not limited to a fatty alcohol, such as, for example, 2-ethylhexanol, and a surfactant or hydrotrope, including but not limited to ammonium xylene sulfonate (for example, StepanateTM AXS, Stepan Company) or sodium xylene sulfonate (for example, StepanateTM SXS-40, Stepan Company or SXS-40, SynerChem). In at least one embodiment, the breaker-containing slurry is prepared by blending the ingredients together using a blender equipped with a 3-blade or a 4-blade propeller stirrer.
[0026] The present non-phosphorus hydrocarbon gelling system advantageously contains a surfactant or hydrotrope which acts to facilitate gellation by increasing the rate of dispersion of the flowable fluid gellant in the hydrocarbon fractionating fluid and facilitating the cross-linking process. In at least one embodiment, the surfactant or hydrotrope is advantageously included in a breaker-containing slurry as described above. In embodiments where the surfactant or hydrotrope is not included in a breaker-containing slurry, the surfactant or hydrotrope can be added separately to the non-phosphorus hydrocarbon gelling system. Suitable surfactants or hydrotropes are selected from ammonium xylene sulfonate (for example, StepanateTM AXS, Stepan Company) and sodium xylene sulfonate (for example, StepanateT"' SXS, Stepan Company or SXS-40, SynerChem).
[0027] Other features of the present non-phosphorus hydrocarbon gelling system will become apparent to the person of skill in the art from the following non-limiting examples.
EXAMPLES
Example I
Preparation of flowable fluid gellant [0028] To propylene carbonate (JeffsolTM PC) (60 g) in a 400 mL beaker stirred at 1000 rpm using a blender equipped with a 3-blade propeller stirrer is slowly added aluminum 2-ethylhexanoate (CalfordTM G760) (75 g) while increasing the blender speed to 4000 rpm.
Blending is continued for 30 minutes at 4000 rpm, then a further portion of aluminum 2-ethylhexanoate (15 g) is added to the mixture. The blender is stopped for 10-15 minutes to allow the mixture to cool, and blending is continued at 4000 rpm for a further 30 minutes. The mixture is left to stand overnight.
Example 2 Preparation of enhancer [0029] A mixture of rosin-modified phenolic resin (RAYBOTM 77, 1.5 g) and dimerised fatty acids (Unidyme 41, 8.35 g) in a 25 mL plastic vial is heated at 50 C until total dissolution occurs.
Example 3 Preparation of breaker-containing slurry [0030] A mixture of mineral oil drilling fluid (PureDrillTM HT40, 37.5 g) and clay gellant (BentoneTM 150, 0.5 g) is vigorously blended at room temperature for 5 minutes. To this mixture is added 2-ethylhexanol (5.0 g) and magnesium oxide (MgO hardburned 1 OCR, 7.0 g) and vigorous blending is continued for a further 5 minutes. To this mixture is added sodium xylene sulfonate (SXS-40, SynerChem, 50.0 g) and blending is continued for 30 minutes at room temperature.
Example 4 Alternate preparation of breaker-containing slurry [0031] A mixture of mineral oil drilling fluid (PureDrillTM HT40, 37.5 g) and clay gellant (BentoneT"' 150, 0.5 g) is vigorously blended at room temperature for 5 minutes. To this mixture is added 2-ethylhexanol (5.0 g) and magnesium oxide (MgO hardburned 1 OCR, 7.0 g) and vigorous blending is continued for a further 5 minutes. To this mixture is added ammonium xylene sulfonate (StepanateTM AXS, 50.0 g) and blending is continued for 30 minutes at room temperature.
Example 5 Preparation and properties of hydrocarbon fracturing fluid [0032] A mixture of flowable fluid gellant prepared as described in Example 1 (15.0 L/m3), accelerator (RAYBOTM 77, 2.5 L/m3), enhancer prepared as described in Example 2 (0.5 Um), and a breaker-containing slurry prepared as described in Example 3 (0.5 Um3) in a base hydrocarbon fluid (TSO 9001) is blended for 2 minutes at 3000 rpm and room temperature in a standard CAFRAMO blender equipped with a 3 blade propeller stirrer. The Brookfield viscosity of the mixture is measured at 70 C.
Time (min) n' k'(Pa.s"') 2 0.31 16.32 0.04 127.68 0.00 170.4 30 t 0.00 150.24 Plots of the viscosity and n' values against time are shown in Figures 1 and 2.
Example 6 Effect of concentration of flowable fluid gellant on properties of hydrocarbon fracturing fluid [0033] Individual batches of hydrocarbon fracturing fluid are prepared, using the method of Example 5, containing flowable fluid gellant prepared as described in Example 1 (10.0 L/m3, 12.5 L/m3, or 15.0 L/m3 in separate batches), accelerator (RAYBOTM 77, 2.5 L/m3), enhancer prepared as described in Example 2 (0.5 L/m3), and a breaker-containing slurry prepared as described in Example 3 (1.0 L/m3) in a base hydrocarbon fluid (TSO 9001). The plots of n' and viscosity for these individual batches are shown in Figures 3 and 4, respectively.
Example 7 Effect of breaker on properties of hydrocarbon fracturing fluid based on Diesel P40 [0034] Individual batches of hydrocarbon fracturing fluid are prepared, using the method of Example 5, containing flowable fluid gellant prepared as described in Example 1 (10.0 L/m) , accelerator (RAYBOU77, 2.5 L/m3), enhancer prepared as described in Example 2 (0.5 L/m), and breaker-containing slurries prepared as described in Examples 3 and 4 (in separate batches, 1.0 Um) in a base hydrocarbon fluid (Diesel P40). The plots of n' and viscosity for these individual batches are shown in Figures 5 and 6, respectively.
Example 8 Effect of breaker on properties of hydrocarbon fracturing fluid based on TSO
[0035] Individual batches of hydrocarbon fracturing fluid are prepared, using the method of Example 5, containing flowable fluid gellant prepared as described in Example 1 (10.0 Um), accelerator (RAYBOTM 77, 2.5 L/m3), enhancer prepared as described in Example 2 (0.5 L/m) , and breaker-containing slurries prepared as described in Examples 3 and 4 (in separate batches, 1.0 L_/m'`) in a base hydrocarbon fluid (TSO 9001). The plots of n' and viscosity for these individual batches are shown in Figures 7 and 8, respectively.
[0036] The above-described embodiments of the present invention are meant to be illustrative of embodiments of the present non-phosphorus hydrocarbon gelling system and are not intended to limit the scope thereof. The person of skill in the art will be aware of various changes and modifications to the above-described embodiments consistent with the description as a whole, which are intended to be included. Reference to an element in the singular, such as, for example by use of the article "a" or "an", is not intended to mean "one and only one" unless specifically so stated, but rather "one or more". Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.
[0011 ] Figure 2 is a plot of viscosity and n' (the power law exponent from viscosity power law equations) against time for the embodiment of Figure 1;
[0012] Figure 3 is a comparative plot of n' against time for embodiments of hydrocarbon fracturing fluids prepared using the present non-phosphorus hydrocarbon gelling system containing different concentrations of flowable fluid gellant;
[0013] Figure 4 is a comparative plot of viscosity against time for the embodiments of Figure 3;
[0014] Figure 5 is a comparative plot of n' against time for embodiments of hydrocarbon fracturing fluids prepared in Diesel P40 using the present non-phosphorus hydrocarbon gelling system containing different breaker-containing slurries;
[0015] Figure 6 is a comparative plot of viscosity against time for the embodiments of Figure 5;
[0016] Figure 7 is a comparative plot of n' against time for embodiments of hydrocarbon fracturing fluids prepared in TSO 9001 using the present non-phosphorus hydrocarbon gelling system containing different breaker-containing slurries; and [0017] Figure 8 is a comparative plot of viscosity against time for the embodiments of Figure 7.
Detailed Description [0018] In at least one embodiment, the present non-phosphorus hydrocarbon gelling system comprises a flowable fluid gellant; an accelerator; an enhancer; a breaker or a breaker-containing slurry; and optionally a surfactant. The non-phosphorus hydrocarbon gelling system is mixed with a base hydrocarbon fluid, including but not limited to Diesel P40 and TSO 9001, so as to form a gel which can be used as a hydrocarbon fracturing fluid. In at least one embodiment, the non-phosphorus hydrocarbon gelling system is added to the hydrocarbon fluid so that the mixture contains about 0.5% to about 3.0% (v/v) of a flowable fluid gellant, about 0.1% to about 0.5% (v/v) of an accelerator, about 0.01% to about 0.1% (v/v) of an enhancer, about 0.01 kg/m3 to about 0.2 kg/m3 of a breaker or about 0.05% to about 0.5%
(v/v) of a breaker-containing slurry and optionally about 0.05% to about 0.2% (v/v) of surfactant. In at least one embodiment, the components of the non-phosphorus hydrocarbon gelling system are blended with the base hydrocarbon fluid using a standard blender equipped with a 3-blade or a 4-blade propeller stirrer, following procedures well known in the art.
[0019] In at least one embodiment, such a system advantageously meets one or more of the following criteria:
= shows well known signs of developing gel formation, including but not limited to gel vortex closure, within 2 minutes or less of blending the system with hydrocarbon fluid;
= has a minimum initial viscosity of about 100 cP or higher at about 100 sec';
= has a peak viscosity of about 100 cP to about 1300 cP at about 100 sec', at a temperature of about 50 C to about 90 C;
= has an adjustable gel strength lifetime wherein a viscosity of at least about 100 cP at about 100 sec' is maintained for at least about 20 minutes, and advantageously from about 40 minutes to about 120 minutes;
= shows non-Newtonian visco-elastic properties with a value of n' (the power law exponent from viscosity power law equations) of no more than about 0.5 for at least about 20 minutes;
maintains viscosity properties independently of the temperature, pressure and shear stress; and = should "break" after about 30 minutes, so as to reduce the viscosity to no higher than about 15 cP at about 100 sec'.
Such criteria are measured using procedures which are well known in the art.
[0020] It can be seen from Figures 1, 2, 4, 6 and 8 that the initial viscosity of a hydrocarbon fracturing fluid prepared using the present non-phosphorus hydrocarbon gelling system increases exponentially and very rapidly. Such a rapid initial viscosity increase is a property of the present non-phosphorus hydrocarbon gelling system which strengthens under exposure to shear and temperature stress.
[0021] In at least one embodiment, the flowable fluid gellant comprises an aluminum salt of a fatty acid and a polar fluid. The flowable fluid gellant is a stable fluid which is easy to handle and pump, in contrast to pure aluminum salts of fatty acids, which are generally in a solid powder form. Suitable aluminum salts of fatty acids include, but are not limited to, aluminum 2-ethylhexanoate (aluminum octoate, including but not limited to CALFORDTM
G760). The polar fluid can be any suitable polar fluid known in the art, including but not limited to water, alcohols, ketones, alkylene carbonates, and esters. In at least one embodiment, the polar fluid is propylene carbonate (for example, JeffsolTM PC). In at least one embodiment, the flowable fluid gellant contains up to 70% by weight of aluminum 2-ethylhexanoate in propylene carbonate.
The flowable fluid gellant is advantageously prepared by adding the aluminum salt of the fatty acid to the polar fluid, while blending the mixture with a blender equipped with a 3-blade or a 4-blade propeller stirrer.
[0022] Without being bound by theory, it is believed that the polar fluid acts as a carrier for the aluminum salt of a fatty acid, so as to provide a fluid, easy to handle formulation. In at least one embodiment, the polar fluid also acts as a latent cross-linking agent which can react with the fatty acid aluminum salt, in the presence of the accelerator, to form a web-like network which aids in the gelling process. It is further believed that the accelerator acts to decrease the time needed for the initial gel formation by facilitating this cross-linking reaction. Suitable accelerators include but are not limited to a rosin-modified phenolic resin, including but not limited to RAYBOTM 77 (Raybo Chemical Company).
[0023] The enhancer acts to stabilize the gel so as to maintain a suitable gel strength lifetime, by allowing the gel to develop a stronger micro-viscosity under shear and temperature stress.
Without being bound by theory, it is believed that the enhancer acts to produce a more convoluted cross-linked network. Suitable enhancers include but are not limited to a high rosin acid modified phenolic ester resin or a blend of a rosin-modified phenolic resin with dimerised fatty acids. In at least one embodiment, the enhancer is selected from SI-191-103/30T (Arizona Chemicals), SI-237-119/30T (Arizona Chemicals), and a mixture of RAYBOTM 77 (Raybo Chemical Company) and Unidyme 41 (Arizona Chemicals).
[0024] The breaker acts to allow the viscosity of the system to decrease once the system has fulfilled its purpose as a fracturing fluid, so that the spent fluid can be easily retrieved, or allowed to leak away into the surrounding formation, leaving the propping agent behind in the fracture channel. Suitable breakers include alkaline earth metal oxides, including but not limited to magnesium oxide and calcium oxide. In at least one embodiment, the breaker is hard burned magnesium oxide 10CR.
[0025] The breaker can advantageously be mixed with other materials to form a slurry prior to being added to other components of the non-phosphorus hydrocarbon gelling system. Suitable additional ingredients of such a breaker-containing slurry include but are not limited to a drilling fluid, including but not limited to a mineral oil drilling fluid (for example, PureDrillTM HT40), a gelling agent, including but not limited to a clay gelling agent (for example BENTONETM 150), an activator for the clay gelling agent including but not limited to a fatty alcohol, such as, for example, 2-ethylhexanol, and a surfactant or hydrotrope, including but not limited to ammonium xylene sulfonate (for example, StepanateTM AXS, Stepan Company) or sodium xylene sulfonate (for example, StepanateTM SXS-40, Stepan Company or SXS-40, SynerChem). In at least one embodiment, the breaker-containing slurry is prepared by blending the ingredients together using a blender equipped with a 3-blade or a 4-blade propeller stirrer.
[0026] The present non-phosphorus hydrocarbon gelling system advantageously contains a surfactant or hydrotrope which acts to facilitate gellation by increasing the rate of dispersion of the flowable fluid gellant in the hydrocarbon fractionating fluid and facilitating the cross-linking process. In at least one embodiment, the surfactant or hydrotrope is advantageously included in a breaker-containing slurry as described above. In embodiments where the surfactant or hydrotrope is not included in a breaker-containing slurry, the surfactant or hydrotrope can be added separately to the non-phosphorus hydrocarbon gelling system. Suitable surfactants or hydrotropes are selected from ammonium xylene sulfonate (for example, StepanateTM AXS, Stepan Company) and sodium xylene sulfonate (for example, StepanateT"' SXS, Stepan Company or SXS-40, SynerChem).
[0027] Other features of the present non-phosphorus hydrocarbon gelling system will become apparent to the person of skill in the art from the following non-limiting examples.
EXAMPLES
Example I
Preparation of flowable fluid gellant [0028] To propylene carbonate (JeffsolTM PC) (60 g) in a 400 mL beaker stirred at 1000 rpm using a blender equipped with a 3-blade propeller stirrer is slowly added aluminum 2-ethylhexanoate (CalfordTM G760) (75 g) while increasing the blender speed to 4000 rpm.
Blending is continued for 30 minutes at 4000 rpm, then a further portion of aluminum 2-ethylhexanoate (15 g) is added to the mixture. The blender is stopped for 10-15 minutes to allow the mixture to cool, and blending is continued at 4000 rpm for a further 30 minutes. The mixture is left to stand overnight.
Example 2 Preparation of enhancer [0029] A mixture of rosin-modified phenolic resin (RAYBOTM 77, 1.5 g) and dimerised fatty acids (Unidyme 41, 8.35 g) in a 25 mL plastic vial is heated at 50 C until total dissolution occurs.
Example 3 Preparation of breaker-containing slurry [0030] A mixture of mineral oil drilling fluid (PureDrillTM HT40, 37.5 g) and clay gellant (BentoneTM 150, 0.5 g) is vigorously blended at room temperature for 5 minutes. To this mixture is added 2-ethylhexanol (5.0 g) and magnesium oxide (MgO hardburned 1 OCR, 7.0 g) and vigorous blending is continued for a further 5 minutes. To this mixture is added sodium xylene sulfonate (SXS-40, SynerChem, 50.0 g) and blending is continued for 30 minutes at room temperature.
Example 4 Alternate preparation of breaker-containing slurry [0031] A mixture of mineral oil drilling fluid (PureDrillTM HT40, 37.5 g) and clay gellant (BentoneT"' 150, 0.5 g) is vigorously blended at room temperature for 5 minutes. To this mixture is added 2-ethylhexanol (5.0 g) and magnesium oxide (MgO hardburned 1 OCR, 7.0 g) and vigorous blending is continued for a further 5 minutes. To this mixture is added ammonium xylene sulfonate (StepanateTM AXS, 50.0 g) and blending is continued for 30 minutes at room temperature.
Example 5 Preparation and properties of hydrocarbon fracturing fluid [0032] A mixture of flowable fluid gellant prepared as described in Example 1 (15.0 L/m3), accelerator (RAYBOTM 77, 2.5 L/m3), enhancer prepared as described in Example 2 (0.5 Um), and a breaker-containing slurry prepared as described in Example 3 (0.5 Um3) in a base hydrocarbon fluid (TSO 9001) is blended for 2 minutes at 3000 rpm and room temperature in a standard CAFRAMO blender equipped with a 3 blade propeller stirrer. The Brookfield viscosity of the mixture is measured at 70 C.
Time (min) n' k'(Pa.s"') 2 0.31 16.32 0.04 127.68 0.00 170.4 30 t 0.00 150.24 Plots of the viscosity and n' values against time are shown in Figures 1 and 2.
Example 6 Effect of concentration of flowable fluid gellant on properties of hydrocarbon fracturing fluid [0033] Individual batches of hydrocarbon fracturing fluid are prepared, using the method of Example 5, containing flowable fluid gellant prepared as described in Example 1 (10.0 L/m3, 12.5 L/m3, or 15.0 L/m3 in separate batches), accelerator (RAYBOTM 77, 2.5 L/m3), enhancer prepared as described in Example 2 (0.5 L/m3), and a breaker-containing slurry prepared as described in Example 3 (1.0 L/m3) in a base hydrocarbon fluid (TSO 9001). The plots of n' and viscosity for these individual batches are shown in Figures 3 and 4, respectively.
Example 7 Effect of breaker on properties of hydrocarbon fracturing fluid based on Diesel P40 [0034] Individual batches of hydrocarbon fracturing fluid are prepared, using the method of Example 5, containing flowable fluid gellant prepared as described in Example 1 (10.0 L/m) , accelerator (RAYBOU77, 2.5 L/m3), enhancer prepared as described in Example 2 (0.5 L/m), and breaker-containing slurries prepared as described in Examples 3 and 4 (in separate batches, 1.0 Um) in a base hydrocarbon fluid (Diesel P40). The plots of n' and viscosity for these individual batches are shown in Figures 5 and 6, respectively.
Example 8 Effect of breaker on properties of hydrocarbon fracturing fluid based on TSO
[0035] Individual batches of hydrocarbon fracturing fluid are prepared, using the method of Example 5, containing flowable fluid gellant prepared as described in Example 1 (10.0 Um), accelerator (RAYBOTM 77, 2.5 L/m3), enhancer prepared as described in Example 2 (0.5 L/m) , and breaker-containing slurries prepared as described in Examples 3 and 4 (in separate batches, 1.0 L_/m'`) in a base hydrocarbon fluid (TSO 9001). The plots of n' and viscosity for these individual batches are shown in Figures 7 and 8, respectively.
[0036] The above-described embodiments of the present invention are meant to be illustrative of embodiments of the present non-phosphorus hydrocarbon gelling system and are not intended to limit the scope thereof. The person of skill in the art will be aware of various changes and modifications to the above-described embodiments consistent with the description as a whole, which are intended to be included. Reference to an element in the singular, such as, for example by use of the article "a" or "an", is not intended to mean "one and only one" unless specifically so stated, but rather "one or more". Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.
Claims (11)
1. A non-phosphorus hydrocarbon gelling system comprising:
(a) a flowable fluid gellant comprising aluminum 2-ethylhexanoate and a polar fluid;
(b) an accelerator;
(c) an enhancer;
(d) a breaker or a breaker-containing slurry; and (e) optionally a surfactant or hydrotrope.
(a) a flowable fluid gellant comprising aluminum 2-ethylhexanoate and a polar fluid;
(b) an accelerator;
(c) an enhancer;
(d) a breaker or a breaker-containing slurry; and (e) optionally a surfactant or hydrotrope.
2. The non-phosphorus hydrocarbon gelling system of claim 1 wherein the polar fluid is propylene carbonate.
3. The non-phosphorus hydrocarbon gelling system of any one of claims 1 or 2 wherein the accelerator is a rosin-modified phenolic resin.
4. The non-phosphorus hydrocarbon gelling system of any one of claims 1 to 3 wherein the enhancer is a blend of a rosin-modified phenolic resin with dimerised fatty acids.
5. The non-phosphorus hydrocarbon gelling system of any one of claims 1 to 4 wherein the breaker is hardburned magnesium oxide.
6. The non-phosphorus hydrocarbon gelling system of any one of claims 1 to 4 wherein the breaker-containing slurry comprises hardburned magnesium oxide, a drilling fluid, a gelling agent, a fatty alcohol, and a surfactant or hydrotrope.
7. The non-phosphorus hydrocarbon gelling system of any one of claims 1 to 6 wherein the surfactant or hydrotrope is ammonium xylene sulfonate or sodium xylene sulfonate.
8. A flowable fluid gellant comprising aluminum 2-ethylhexanoate and a polar fluid.
9. The flowable fluid gellant of claim 8 wherein the polar fluid is propylene carbonate.
10. A method of producing a hydrocarbon gel comprising adding to a hydrocarbon fluid:
(a) a flowable fluid gellant comprising aluminum 2-ethylhexanoate and a polar fluid;
(b) an accelerator;
(c) an enhancer;
(d) a breaker or a breaker-containing slurry; and (e) optionally a surfactant or hydrotrope.
(a) a flowable fluid gellant comprising aluminum 2-ethylhexanoate and a polar fluid;
(b) an accelerator;
(c) an enhancer;
(d) a breaker or a breaker-containing slurry; and (e) optionally a surfactant or hydrotrope.
11. A hydrocarbon fracturing fluid comprising a hydrocarbon fluid and a non-phosphorus hydrocarbon gelling system according to any one of claims 1 to 7.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US13626008P | 2008-08-22 | 2008-08-22 | |
| US61/136,260 | 2008-08-22 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2676337A1 CA2676337A1 (en) | 2010-02-22 |
| CA2676337C true CA2676337C (en) | 2012-05-15 |
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ID=41722635
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2676337A Expired - Fee Related CA2676337C (en) | 2008-08-22 | 2009-08-21 | Non-phosphorus hydrocarbon gelling system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2676337C (en) |
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2009
- 2009-08-21 CA CA2676337A patent/CA2676337C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2676337A1 (en) | 2010-02-22 |
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