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Collaborating Authors
Ng, Jun Hong
Abstract Corrosion inhibitors used in the petroleum industry are a necessity to include in any acid job. When corrosion occurs to downhole tubulars and equipment, huge expenses are required to maintain the integrity and performance of the well. Unfortunately, commonly used corrosion inhibitors are accompanied with extreme environmental concerns and risk to human health. The recent developments in corrosion inhibitors have resolved the environmental aspect by focusing on biodegradability of these compounds, however, these inhibitors still struggle with issues of toxicity and high temperature stability. The project aims to develop new green, non-toxic, environmentally friendly corrosion inhibitors capable of performing well at high temperature conditions faced in the oil and gas industry. To achieve this goal, 13 commonly available flowers were screened for corrosion inhibition properties. The tests involved using low carbon steel (N-80) coupons and exposing them to 15 wt.% HCl solutions at temperatures between room temperature and 250 °F using a HPHT corrosion reactor to imitate oilfield conditions. A concentration of 0.2-2 wt.% grounded flowers were used to prevent corrosion. Moreover, a control solution containing no corrosion inhibitor was used to establish a corrosion rate for a base case. Upon identifying high performing flowers, extracts of these flowers were subsequently tested to save cost by minimizing quantity needed while achieving acceptable performance. The corrosion inhibition efficiency of the different flowers was compared at various concentrations and temperatures as well as the effect of adding corrosion inhibitor intensifiers. The results revealed that one new inhibitor can be developed from the 13 flower samples tested. The corrosion rate of the flower extract after 6 hours at 150°F was 0.0398 lb/ft. Additionally, this flower extract was assessed at 200°F and 250°F with the addition of 1 wt.% corrosion inhibitor intensifier and exhibited a corrosion rate of 0.00823 lb/ft and 0.0141 lb/ft, respectively. The results in this work share one new naturally occurring, green, non-toxic, high-temperature stable corrosion inhibitors that can be developed from flowers and can successfully protect the tubular during acid treatments achieving rates below the industry standard of 0.05 lb/ft for 6 hours at temperatures up to 250°F.
- North America > United States > Texas (0.69)
- Asia > Middle East > Saudi Arabia (0.69)
- Africa (0.68)
- Water & Waste Management > Water Management > Water & Sanitation Products (1.00)
- Materials > Chemicals > Specialty Chemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Summary Hydrochloric and organic acids have been extensively used to enhance well productivity or injectivity in tight carbonate formations (10 to 50 md). The use of these acids, however, can cause instances of complete production loss. This is especially common due to incompatibilities of the acidizing fluid and oil, which can lead to the formation of acid/oil emulsions and sludge formation. Consequently, it is necessary to properly identify and remove such emulsions or precipitations without causing any further damage. Compatibility studies were conducted using representative crude samples and hydrochloric acid (HCl). The experiments were conducted at various temperatures up to 240°F using high-pressure/high-temperature (HP/HT) aging cells for both live and spent acid samples, in which some of the experiments included an antisludge, an iron-control agent, and a demulsifier. In addition, another set of experiments was performed in the presence of ferric ions (Fe). The total iron concentration in these experiments was varied between 0 and1,000 ppm. The results showed that commonly used acid systems were not compatible with representative oil field samples. The amount of sludge formed and the stability of formed emulsions increased significantly in the presence of ferric ions and was more severe in the presence of hydrogen sulfide (H2S). Using a field case, this paper will cover the methodology used to ascertain the source of formation damage from acidizing, study the different factors that influence the formation of acid/oil emulsion and sludge formation mechanism, and show how they can be removed. In this example, acid/oil emulsions, sludge formation, and improper drilling mud filter-cake removal were the reasons behind the production loss. However, the methodology can be expanded to cater the many acidizing failure cases faced in the industry worldwide.
- North America > United States (1.00)
- Europe (1.00)
- North America > Canada (0.93)
- (2 more...)
- Research Report > New Finding (0.48)
- Research Report > Experimental Study (0.34)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Abstract Gas injection is amongst the oldest and most used enhanced oil recovery (EOR) methods in the petroleum industry. Nevertheless, gas EOR is subject to poor macroscopic sweep efficiency due to the higher mobility and lower density of gas compared to reservoir fluids. Foamed-gas injection can regulate the mobility of gas by trapping a large fraction of the gas inside the porous medium, thereby increasing its apparent viscosity and reducing its relative permeability. However, the poor stability of foam at harsh reservoir temperature and salinity conditions is a major limitation that hinders the effectiveness of the foam flood. A combination of surfactant and nanoparticles (NPs) provides a novel solution to foam stability challenges. This study evaluates the role of NPs on enhancing foam stability. Static and dynamic laboratory tests were conducted along with particle size and zeta potential measurements to capture the foam stability and strength in porous media for a cationic surfactant combined with surface modified silica NPs. The static bulk foam stability was determined by measuring the foam half-life over time. The dynamic foam stability was determined through the mobility reduction factor (MRF) using a micromodel apparatus. The tests were carried out on a variety of NPs concentrations and fixed surfactant concentration. The results from the experiments show that the use of surfactant combined with NPs enhances the stability and strength of the generated foam when compared to the use of surfactant alone. The foam static tests show that the mixture of NPs and surfactants produces foams with smaller bubbles and longer half-life when compared to those in the absence of NPs. The results also demonstrate that the concentration of surfactant and NPs is a crucial parameter for foam stability and that there is an optimal concentration of NPs for strong foam generation. In porous media, the addition of NPs to surfactant solutions results in larger pressure differences across the micromodel chip and, accordingly, greater reduction of gas mobility when compared to those using surfactant solution alone. The results also reveal that the generation of NPs flocs is the main mechanism of foam stabilization enhancement. This work shows that using NPs at carefully selected concentrations in combination with surfactant can improve the foam static and dynamic stability in porous media, effectively lowering the mobility of the injected fluids and, eventually, improving the sweep efficiency of gas compared to the typical application of using surfactant alone.
- North America > United States (1.00)
- Europe (1.00)
- Asia > Middle East > Saudi Arabia > Eastern Province (0.28)
Abstract Hydraulic fracturing technology has grown popular with the rapidly increasing development of tight conventional and unconventional reservoirs. A major concern with this technique is the use of large amounts of water in these treatments. The use of water causes many potential damaging issues in the formation and limits the amount that can be saved for future generations. One solution is waterless fracturing treatments, which were developed to reduce or eliminate the need for water in hydraulic fracturing. Hydraulic fracturing treatments consume at least 200,000 gallons of water in conventional wells and up to 16,000,000 gallons of water in unconventional wells. The pumped water must include clay stabilizers to deal with the sensitive clays in the formation. Additionally, using water poses a risk of inorganic scale precipitation near the wellbore. Water can also cause severe emulsions that can lead to emulsion blockage cases. Moreover, there are significant reports of water blockage cases in tight gas wells. Only a mere 10-30% of pumped water flows back after the treatment, with the rest attached to clays, or stuck in the pores due to high capillary pressures. Water-based fluids can also cause alterations to relative permeability, and liquid holdup cases in many gas wells. These issues can certainly increase near wellbore skin and reduce production rates. At the end of the treatment, water still causes issues related to disposal and separation prior to diverting it to the plant. The main challenges in developing waterless fluids include feasibility, environmental friendliness, and effectiveness to stimulate the reservoir. This review will cover the various waterless fracturing methods such as hydrocarbon-based, liquid CO2, energized, and foamed fluids (CO2 and N2 foams) as well as their advantages and disadvantages. Studies into the properties of these fluids, such as rheology, solubility, compatibility, will also be discussed. Field trials will be examined where applicable. This literature review examines various waterless alternatives to traditional fluids for hydraulic fracturing. From this paper, readers can better understand the nature of waterless technologies and be able to better evaluate these technologies for fracturing purposes.
- North America > United States > Texas (1.00)
- Europe (1.00)
- Asia > Middle East (1.00)
- (3 more...)
- Geology > Mineral > Silicate > Phyllosilicate (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.48)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- North America > United States > West Virginia > Appalachian Basin > Huron Shale Formation (0.99)
- North America > United States > Virginia > Appalachian Basin > Huron Shale Formation (0.99)
- North America > United States > New Mexico > San Juan Basin (0.99)
- (5 more...)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- (9 more...)
Zirconium Crosslinkers: Understanding Performance Variations in Crosslinked Fracturing Fluids
Almubarak, Tariq (Texas A&M University) | Ng, Jun Hong (Texas A&M University) | Nasr-El-Din, Hisham A. (Texas A&M University) | Almubarak, Majed (Saudi Aramco EXPEC ARC) | AlKhaldi, Mohammed (Saudi Aramco EXPEC ARC)
Abstract Borate crosslinkers are the most commonly used crosslinker in fracturing fluids. However, they exhibit lower performance at high temperature, high pressure, high water salinity, and low pH applications. Consequently, zirconium crosslinkers are utilized to address these limitations. Zirconium crosslinking chemistry is complex and depends on many factors such as pH, metal to ligand ratio, ligand order, ionic strength, and type of polymer used, which in turn influence the delay time, thermal stability and shear resistance performance. This work evaluates the rheological performance of four different zirconium crosslinkers with a biopolymer and a synthetic polymer. The tested crosslinkers are manufactured in different chemical structures. The two polymers tested are 40 lb/1,000 gal CMHPG and 40 lb/1,000 gal synthetic polymer. The rheological performance was measured through HPHT rheometer (100 s shear rate) at 200-400°F for 2 hours. The shear tolerance performance was also evaluated under a custom shear rate schedule (100-1000 s). The results show significant variation in crosslinking performance due to the changes in crosslinker chemical structure and type of polymer used. Zirconium lactate and propylene glycol crosslinker shows the highest enhancement in shear and thermal stability with CMHPG based fracturing fluids. Surprisingly, the same crosslinker performed the least with synthetic polymer-based fracturing fluids. However, Zirconium triethanol amine and lactate showed significant enhancements in shear and thermal stability with synthetic polymer-based systems. The results also show and discuss the influence of systematically changing crosslinker ligand order in CMHPG and synthetic polymer-based fracturing fluids. The work studies the influence of the zirconium crosslinker chemical structure on the rheological properties of both biopolymer and synthetic polymer-based fracturing fluids. The performance evaluation shows that delay time, shear and thermal stability can be enhanced by manufacturing the appropriate crosslinker chemical structure, thus reducing additional additives required used and saving cost.
- Asia (1.00)
- North America > United States > Texas (0.47)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Abstract Corrosion inhibitors currently used in the oil and gas industry are associated with environmental concerns and severe health risks. Recent advancements in corrosion inhibition technology had successfully tackled environmental concerns, but still faces issues with toxicity and performance at high temperatures. This work aims to develop environmentally friendly and non-toxic corrosion inhibitors that can overcome these limitations. Extracts of 14 common fruits were tested as sources of potential corrosion inhibitors. In order to determine the inhibition effectiveness of the different fruits, N-80 coupons were exposed to 15 wt.% HCl solutions at temperatures between 77-250 °F with 0.2-2 wt.% of dried ground fruit for 6 hours. In addition, a control solution containing no corrosion inhibitor was used to establish a corrosion rate for a base case. Upon identifying high performing dried ground fruits, extracts of these fruits were subsequently tested to save cost by minimizing quantity needed while achieving acceptable performance. At a concentration of 2 wt.%, fruits 1 and 2 were found to perform the best, exhibiting more than 98% corrosion inhibition efficiency at 77°F. Fruits 11 and 12 were observed to perform the worst, going so far as to enhance corrosion on the coupons. At 150°F, the corrosion rate of fruit extract 1 was 0.00436 lb/ft while that of fruit extract 2 was 0.0277 lb/ft. At 200°F, the addition of a corrosion inhibitor intensifier resulted in a corrosion rate of 0.00130 lb/ft for fruit extract 1 and 0.0173 lb/ft for fruit extract 2. At 250°F, a second corrosion inhibitor intensifier was used. The resulting corrosion rate was 0.0320 lb/ft2 for fruit extract 1 and 0.00963 lb/ft for fruit extract 2. These results show that a naturally occurring, green, non-toxic corrosion inhibitor can be developed from these fruits and can comfortably pass the industry requirement of achieving corrosion rates below 0.05 lb/ft for low carbon steel tubulars. Corrosion during acid treatments causes destruction to the tubulars and downhole equipment. Consequently, this leads to an increase in expenditure to maintain well production rates and well integrity. Therefore, corrosion inhibitors must be included in any acid treatment formulation. The results in this work share two new naturally occurring, green, non-toxic, high-temperature stable corrosion inhibitors that can be developed from fruits and can successfully protect the tubular during acid treatments.
- Africa (0.68)
- North America > United States > Texas (0.47)
- Asia > Middle East > Saudi Arabia (0.29)
- North America > United States > Oklahoma (0.29)
- Water & Waste Management > Water Management > Water & Sanitation Products (1.00)
- Materials > Chemicals > Specialty Chemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Dual-Polymer Hydraulic-Fracturing Fluids: A Synergy Between Polysaccharides and Polyacrylamides
Almubarak, Tariq (Texas A&M University) | Ng, Jun Hong (Texas A&M University) | Nasr–El–Din, Hisham A. (Texas A&M University) | Sokhanvarian, Khatere (Sasol Performance Chemicals) | AlKhaldi, Mohammed (Saudi Aramco)
Summary As exploration for oil and gas continues, it becomes necessary to produce from deeper formations, and to meet the challenge of low permeability and higher temperatures. Unconventional shale formations are addressed with slickwater fracturing fluids, owing to the shale's unique geomechanical properties. On the other hand, conventional formations require crosslinked fracturing fluids to properly enhance productivity. Guar and its derivatives have a history of success in crosslinked hydraulic–fracturing fluids. However, they require higher polymer loading to withstand higher–temperature environments. This leads to an increase in mixing time and additive requirements. Most importantly, as a result of high polymer loading, they do not break completely and thus generate residual–polymer fragments that can plug the formation and significantly reduce fracture conductivity. In this work, a new hybrid dual–polymer hydraulic–fracturing fluid was developed. The fluid consists of a guar derivative and a polyacrylamide–based synthetic polymer. Compared with conventional fracturing fluids, this new system is easily hydrated, requires fewer additives, can be mixed “on the fly,” and is capable of maintaining excellent rheological performance at low polymer loadings. The polymer mixture solutions were prepared at a total polymer concentration of 20 to 40 lbm/1,000 gal at volume ratios of 2:1, 1:1, and 1:2. The fluids were crosslinked with a metallic crosslinker and broken with an oxidizer at 300°F. Testing focused on crosslinker/polymer–ratio analysis to effectively lower loading while maintaining sufficient performance to carry proppant at this temperature. A high–pressure/high–temperature (HP/HT) rheometer was used to measure viscosity, storage modulus, and fluid–breaking performance. An HP/HT aging cell and HP/HT see–through cell were used for proppant settling. Fourier–transform infrared (FTIR) spectroscopy, Cryo scanning electron microscopy (Cryo–SEM), and an HP/HT rheometer were also used to understand the interaction. Results indicated that the dual–polymer fracturing fluid was able to generate stable viscosity at 300°F and 100 s as well as generate a higher viscosity compared with the individual–polymer fracturing fluid. Also, properly understanding and tuning the crosslinker to the polymer ratio generated excellent performance at 20 lbm/1,000 gal. The two polymers formed an improved crosslinking network that enhanced proppant–carrying properties. This fluid also demonstrated a clean and controlled breaking performance with an oxidizer. Extensive experiments were pursued to evaluate the new dual–polymer system for the first time. This system exhibited a positive interaction between the polysaccharide and polyacrylamide families and generated excellent rheological properties. The major benefit of using a mixed–polymer system is reduced polymer loading. Lower loading is highly desirable because it reduces material cost, eases field operation, and potentially lowers damage to the fracture face, proppant pack, and formation.
- North America > United States > Texas (1.00)
- North America > Canada (1.00)
- Asia > Middle East (0.94)
- Europe (0.88)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.74)
- Geology > Geological Subdiscipline > Geomechanics (0.54)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Summary Typically, water-based fracturing treatments consume a large volume of fresh water. Providing consistent freshwater sources is difficult and sometimes not feasible, especially in remote areas and offshore operations. Therefore, several seawater-based fracturing fluids have been developed in an effort to preserve freshwater resources. However, none of these fluids minimizes fracture-face skin and proppant-conductivity impairment, which can be critical for unconventional well treatments. Several experiments and design iterations were conducted to tailor raw-seawater-based fracturing fluids. These fluids were designed to have rheological properties that can transport proppant under dynamic and static conditions. The optimized seawater-based fracturing-fluid formulas were developed such that no scale forms when additives are mixed in or when the fracturing-fluid filtrate is mixed with different formation brines. The tests were conducted using a high-pressure/high-temperature (HP/HT) rheometer, coreflood, and by aging cells at 250 to 300°F. The developed seawater-based fracturing fluids were optimized with an apparent viscosity greater than 100 cp at a shear rate of 100 seconds and a temperature of 300°F for more than 1 hour. The use of polymeric- and phosphonate-based scale inhibitors (SIs) prevented the formation of severe calcium sulfate (CaSO4) scale in mixtures of seawater and formation brines at 300°F. Controlling the pH of fracturing fluids prevented magnesium and calcium hydroxide precipitation that occurs at a pH value of greater than 9.5. Most importantly, SIs had a negative effect on the viscosity of seawater fracturing fluid during testing because of their negative interaction with metallic crosslinkers. The developed seawater-based fracturing fluids were applied for the first time in an unconventional and a conventional carbonate well and showed very promising results; details of field treatments are discussed in this paper.
- Europe (1.00)
- North America > Canada (0.67)
- Asia > Middle East > Saudi Arabia (0.48)
- (2 more...)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Constituents > Salts/Sulphates/Scales (0.34)
- North America > United States > California > Sacramento Basin > 3 Formation (0.99)
- Asia > Vietnam > South China Sea > Cuu Long Basin > Block 09-1 > Bach Ho Field (0.99)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Shale Formation (0.94)
- (6 more...)
Pushing the Thermal Stability Limits of Hydraulic Fracturing Fluids
Almubarak, Tariq (Texas A&M University) | Li, Leiming (Aramco Services Company) | Nasr-El-Din, Hisham (Texas A&M University) | Ng, Jun Hong (Texas A&M University) | Sokhanvarian, Khatere (Sasol Chemical) | Alkhaldi, Mohammed (Saudi Aramco) | Almubarak, Sama (Saudi Aramco)
Abstract In order to satisfy the demand for oil and gas, it becomes increasingly necessary to produce from formations that are deeper, have low permeability, and higher temperature. Conventionally, hydraulic fracturing fluids make use of viscosifiers such as guar and its derivatives to generate the rheological properties required during the fracturing process. However, to withstand the high-temperature environments, higher loadings of polymer is required. This leads to an increase in polymer and additive concentrations. Most importantly, these higher loading fluids do not break completely, and generate residual polymer fragments that can plug the formation and reduce fracture conductivity significantly. This work builds on previous work which introduced a new hybrid dual polymer hydraulic fracturing fluid that was developed for high-temperature applications. The fluid consists of a guar derivative and a polyacrylamide-based synthetic polymer. Compared to conventional fracturing fluids, this new system is easily hydrated, requires less additives, can be mixed on the fly, and is capable of maintaining excellent rheological performance at low polymer loadings. In this work, the fluid is further optimized to withstand even higher temperatures up to 400°F. Total polymer loadings of 30 lb/1,000 gal and 40 lb/1,000 gal dual polymer fracturing fluid were tested in this work and were prepared in the ratio of 1:1 and 1:2 (CMHPG: Synthetic). They were then crosslinked with a metallic crosslinker and placed in a HPHT rheometer to measure the viscosity between 200 and 400°F. After observing the failure temperature of the mixtures, additives such as buffers, crosslinking delayers, and oxygen scavengers were added and tested at temperatures above that point. The type of crosslinker used was also varied to observe the effects of the rate of release of the metallic crosslinker on thermal stability. The results indicate that the 1:2 (CMHPG: Synthetic) mixture performed better at temperatures exceeding 330°F than the 1:1 mixture. The failure point of both mixtures was observed to be 350°F for the latter while the former failed at 370°F. The addition of a crosslinker that allowed a more controllable release was observed to improve the thermal stability of the fluid mixture above 370°F by increasing the polymer's shear tolerance. The addition of additives to the mixture was shown to improve the thermal stability of the solution to varying degrees. Of the three additives, the most significant enhancement came from the addition of oxygen scavengers while the least was from the buffer solution.
- Asia (0.94)
- North America > United States > Texas (0.49)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Improving Hydraulic Fracturing Fluids Through Dual Polymer Technology
Almubarak, Tariq (Texas A&M University) | Ng, Jun Hong (Texas A&M University) | Sokhanvarian, Khatere (Sasol Performance Chemicals, Texas A&M) | AlKhaldi, Mohammed (Saudi Aramco EXPEC ARC) | Nasr-El-Din, Hisham (Texas A&M University)
Abstract As exploration for oil and gas continues, it becomes necessary to produce from formations that are deeper, have low permeability, and higher temperature. Conventionally, guar and its derivatives have been successfully utilized as hydraulic fracturing fluids. However, they require higher polymer loading to withstand the high-temperature environments. This leads to an increase in mixing time and additive requirements. Most importantly, they do not break completely and generate residual polymer fragments that can plug the formation and reduce fracture conductivity significantly. In this work, a new hybrid dual polymer hydraulic fracturing fluid is developed for high-temperature applications. The fluid consists of a guar derivative and a polyacrylamide-based synthetic polymer. Compared to conventional fracturing fluids, this new system is easily hydrated, requires fewer additives, can be mixed on the fly, and is capable of maintaining excellent rheological performance at low polymer loadings. The polymer mixture solutions were prepared at concentrations ranging from 20 to 40 lb/1,000 gal at a ratio of 2:1, 1:1, and 1:2. The fluids were crosslinked with a metallic crosslinker and broken with an oxidizer at 300-350°F. Testing focused on crosslinker to polymer ratio analysis to effectively lower loading while maintaining sufficient performance to carry proppant at these harsh conditions. HP/HT rheometer was used to measure viscosity and elastic modulus. HP/HT see-through cell was utilized for proppant settling. Results indicate that the dual polymer fracturing fluid is able to generate stable viscosity at 300-350°F and 100 s. Results show that the dual polymer fluid can generate higher viscosity compared to the individual single polymer system. Also, properly understanding and tuning the crosslinker to polymer ratio generates excellent performance even at 20 lb/1,000 gal. The two polymers form a shared crosslinking network that improves proppant carrying capacity at lower polymer loadings and high temperatures. It also demonstrates a clean and controlled break performance with an oxidizer. The major benefit of using a mixed polymer system is to reduce polymer loading at harsher conditions. Lower loading is highly desirable because it reduces material cost, eases field operation and lowers damage to the fracture face, proppant pack and formation.
- North America > United States > Texas (1.00)
- Asia > Middle East (0.94)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)