Laboratory Investigation of Permeability Impairment Caused by Asphaltene Precipitation during Screening for Gas-Injection Enhanced Oil Recovery and Pressure Change in a Major Gulf of Mexico Field

SPE Journal ◽  
2021 ◽  
pp. 1-21
Author(s):  
M. R. Fassihi ◽  
E. Turek ◽  
M. Matt Honarpour ◽  
D. Peck ◽  
R. Fyfe
Keyword(s):  
Gulf Of Mexico ◽  
Gas Injection ◽  
Rock Surface ◽  
Permeability Reduction ◽  
Test Results ◽  
Asphaltene Precipitation ◽  
The Core ◽  
Asphaltene Deposition ◽  
Core Permeability ◽  
Permeability Impairment

Summary As part of studying miscible gas injection (GI) in a major field within the Green Canyon protraction area in the Gulf of Mexico (GOM), asphaltene-formation risk was identified as a key factor affecting a potential GI project. The industry has not conducted many experiments to quantify the effect of asphaltenes on reservoir and well performance under GI conditions. In this paper we discuss a novel laboratory test for evaluating the asphaltene effect on permeability. The goals of the study were to define the asphaltene-precipitation envelope using blends of reservoir fluid and injection gas, and measure permeability reduction caused by asphaltene precipitation in a core under GI. To properly analyze the effect of GI, a suite of fluid-characterization studies was conducted, including restored-oil samples, compositional analysis, constant composition expansion (CCE), and differential vaporization. Miscibility conditions were defined through slimtube-displacement tests. Gas solubility was determined through swelling tests complemented by asphaltene-onset-pressure (AOP) testing. The unique procedure was developed to estimate the effect of asphaltene deposition on core permeability. The 1-ft-long core was saturated with the live-oil and GI mixture at a pressure greater than the AOP, and then pressure was depleted to a pressure slightly greater than the bubblepoint. Several cycles of charging and depletion were conducted to mimic continuous flow of oil along the path of injected gas and thereby to observe the accumulation of asphaltene on the rock surface. The test results indicated that during this cyclic asphaltene-deposition process, the core permeability to the live mixture decreased in the first few cycles but appeared to stabilize after Cycle 5. The deposited asphaltenes were analyzed further through environmental scanning electron microscopy (ESEM), and their deposition was confirmed by mass balance before and after the tests. Finally, a relationship was established between permeability reduction and asphaltene precipitation. The results from the asphaltene-deposition experiment show that for the sample, fluids, and conditions used, permeability is impaired as asphaltene flocculates and begins to coat the grain surfaces. This impairment reaches a plateau at approximately 40% of the initial permeability. Distribution of asphaltene along the core was measured at the end by segmenting the core and conducting solvent extraction on each segment. Our recommendation is numerical modeling of these test results and using this model to forecast the magnitude of the permeability impairment in a reservoir setting during miscible GI.

An Integrated Simulation Approach to Predict Permeability Impairment under Simultaneous Aggregation and Deposition of Asphaltene Particles

SPE Journal ◽  
2021 ◽  
pp. 1-14
Author(s):  
Xin Su ◽  
Rouzbeh G. Moghanloo ◽  
Minhui Qi ◽  
Xiang-an Yue
Keyword(s):  
Porous Media ◽  
Particle Aggregation ◽  
Formation Damage ◽  
Permeability Reduction ◽  
Simulation Approach ◽  
Pore Connectivity ◽  
Integrated Simulation ◽  
Asphaltene Deposition ◽  
Simulation Results ◽  
Permeability Impairment

Summary Formation damage mechanisms in general lower the quality of the near wellbore, often manifested in the form of permeability reduction, and thus reducing the productivity of production wells and injectivity of injection wells. Asphaltene deposition, as one of the important causes, can trigger serious formation damage issues and significantly restrict the production capacity of oil wells. Several mechanisms acting simultaneously contribute to the complexity associated with prediction of permeability impairment owing to asphaltene deposition; thus, integration of modeling efforts for asphaltene aggregation and deposition mechanisms seems inevitable for improved predictability. In this work, an integrated simulation approach is proposed to predict permeability impairment in porous medium. The proposed approach is novel because it integrates various mathematical models to study permeability impairment considering porosity reduction, particle aggregation, and pore connectivity loss caused by asphaltene deposition. To improve the accuracy of simulation results, porous media is considered as a bundle (different size) of capillary tubes with dynamic interconnectivity. The total volume change of interconnected tubes will directly represent permeability reduction realized in porous media. The prediction of asphaltene deposition in porous media is improved in this paper via integration of the particle aggregation model into calculation. The simulation results were verified by comparing with existing experimental data sets. After that, a sensitivity analysis was performed to study parameters that affect permeability impairment. The simulation results show that our permeability impairment model—considering asphaltene deposition, aggregation, and pore connectivity loss—can accurately reproduce the experimental results with fewer fitting or empirical parameters needed. The sensitivity analysis shows that longer aggregation time, higher flow velocity, and bigger precipitation concentration will lead to a faster permeability reduction. The findings of this study can help provide better understanding of the permeability impairment caused by asphaltene deposition and pore blockage, which provides useful insights for prediction of production performance of oil wells.

Asphaltene Thermodynamic Precipitation during Miscible Nitrogen Gas Injection

SPE Journal ◽  
2021 ◽  
pp. 1-18
Author(s):  
Mukhtar Elturki ◽  
Abdulmohsin Imqam
Keyword(s):  
Pore Size ◽  
Oil Recovery ◽  
Mixing Time ◽  
Gas Injection ◽  
Injection Pressure ◽  
Weight Percent ◽  
Asphaltene Precipitation ◽  
Nitrogen Gas ◽  
Recovery Method ◽  
Asphaltene Deposition

Summary For many years, miscible gas injection has been the most beneficial enhanced oil recovery method in the oil and gas industry. However, injecting a miscible gas to displace oil often causes the flocculation and deposition of asphaltenes, which subsequently leads to a number of production problems. Nitrogen gas (N2) injection has been used to enhance oil recovery in some oil fields, seeking to improve oil recovery. However, few works have implemented N2 injection and investigated its effect on asphaltene precipitation and deposition. This research investigated the N2 miscible flow mechanism in nanopores and its impact on asphaltene precipitations, which can plug pores and reduce oil recovery. First, a slimtube was used to determine the minimum miscibility pressure (MMP) of N2 to ensure that all of the experiments would be conducted at levels above the MMP. Second, filtration experiments were conducted using nanocomposite filter membranes to study asphaltene deposition on the membranes. A filtration apparatus was designed specifically and built to accommodate the filter membranes. The factors studied include N2 injection pressure, temperature, N2 mixing time, and pore size heterogeneity. Visualization tests were conducted to highlight the asphaltene precipitation process over time. Increasing the N2 injection pressure resulted in an increase in the asphaltene weight percent in all experiments. Decreasing the pore size of the filter membranes increased the asphaltene weight percent. More N2 mixing time also resulted in an increase in asphaltene weight percent, especially early in the process. Visualization tests revealed that after 1 hour, the asphaltene particles were conspicuous, and more asphaltene clusters were found in the test tubes of the oil samples from the filter with the smallest pore size. Chromatography analysis of the produced oil confirmed the reduction in the asphaltene weight percent. Microscopy and scanning electron microscopy (SEM) imaging of the filter membranes indicated significant pore plugging from the asphaltenes, especially for the smaller pore sizes. This research highlights the severity of asphaltene deposition during miscible N2 injection in nanopore structures so as to understand the main factors that may affect the success of miscible N2 injection in unconventional reservoirs.

Competitive position of the expanded Panama Canal in the shipment of liquefied natural gas

2018 ◽  
Vol 233 (4) ◽  
pp. 1154-1176 ◽  
Author(s):  
Luis Carral ◽  
Javier Tarrío-Saavedra ◽  
Diego Crespo-Pereira ◽  
Marina Fernández-Campoamor ◽  
Rodolfo Sabonge
Keyword(s):  
Natural Gas ◽  
Gulf Of Mexico ◽  
Gas Injection ◽  
The United States ◽  
Liquefied Natural Gas ◽  
Panama Canal ◽  
Order Book ◽  
Propulsion Systems ◽  
Competitive Position ◽  
Alternative Routes

The appearance of new gas extraction technologies has led to surplus production in the United States (Gulf of Mexico). At the same time, energy consumption in Asia has increased significantly and Japan has introduced important changes to its post-Fukushima energy policies. Taken together, these factors have resulted in an imbalance in production and consumption between the Atlantic and Pacific Maritime Areas. Over the same period of time, the Panama Canal expansion opened, permitting transit by liquefied natural gas vessels for the first time. These developments are reflected in the current order book for liquefied natural gas carriers, which is composed entirely of ships in the new Neopanamax category. The canal transit fees and new propulsion systems for these ships—dual fuel diesel electric and electronically controlled gas injection—significantly impact the price of cargo at the destination. This study conducts a sensitivity analysis of the variables for transportation costs in order to determine the expanded Canal’s competitive position. In addition, the study uses a Monte Carlo simulation to obtain the most representative values for total cost based on factors such as the type of propulsion and fuel as well as the distance traveled. The analysis clearly demonstrates the competitiveness of exporting liquefied natural gas via the Panama Canal from terminals in the Gulf of Mexico and the Caribbean to consumers in Asia, as well as the competitiveness of the canal itself versus alternative routes. With respect to propulsion systems, the study demonstrates the greater competitive advantage of electronically controlled gas injection propulsion.

Experimental Investigation of Asphaltene-Induced Formation Damage Caused by Pressure Depletion of Live Reservoir Fluids in Porous Media

SPE Journal ◽  
2018 ◽  
Vol 24 (01) ◽  
pp. 01-20 ◽  
Author(s):  
Omid Mohammadzadeh ◽  
Shawn David Taylor ◽  
Dmitry Eskin ◽  
John Ratulowski
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Flow Rate ◽  
Formation Damage ◽  
Bulk Fluid ◽  
Asphaltene Content ◽  
Pressure Depletion ◽  
Asphaltene Deposition ◽  
Permeability Impairment ◽  
Live Oil

Summary One of the complex processes of permeability impairment in porous media, especially in the near-wellbore region, is asphaltene-induced formation damage. During production, asphaltene particles precipitate out of the bulk fluid phase because of pressure drop, which might result in permeability reduction caused by both deposition of asphaltene nanoparticles on porous-medium surfaces and clogging of pore throats by larger asphaltene agglomerates. Experimental data will be used to identify the parameters of an impairment model being developed. As part of a larger effort to identify key mechanisms of asphaltene deposition in porous media and develop a model for asphaltene impairment by pressure depletion, this paper focuses on a systematic design and execution of an experimental study of asphaltene-related permeability damage caused by live-oil depressurization along the length of a flow system. An experiment was performed using a custom-designed 60-ft slimtube-coil assembly packed with silica sands to a permeability of 55 md. The customized design included a number of pressure gauges at regular intervals along the coil length, which enabled real-time measurement of the fluid-pressure profile across the full length of the slimtube coil. The test was performed on a well-characterized recombined live oil from the Gulf of Mexico (GOM) that is a known problematic asphaltenic oil. Under a constant differential pressure, the injection flow rate of the live oil through the slimtube coil decreased over time as the porous medium became impaired. During the impairment stage, samples of the produced oil were collected on a regular basis for asphaltene-content measurement. After more than 1 month, the impairment test was terminated; the live oil was purged from the slimtube coil with helium at a pressure above the asphaltene-onset pressure (AOP); and the entire system was gently depressurized to bring the coil to atmospheric conditions while preserving the asphaltene-damaged zones of the coil. The permeability and porosity of the porous medium changed because of asphaltene impairment that was triggered by pressure depletion. Results indicated that the coil permeability was impaired by approximately 32% because of pressure depletion below the AOP, with most of the damage occurring in the latter section of the tube, which operated entirely below the AOP. Post-analytical studies indicated lower asphaltene content of the produced-oil samples compared with the injecting fluid. The distribution of asphaltene deposits along the length of the coil was determined by cutting the slimtube coil into 2- to 3-ft-long sections and using solvent extraction to collect the asphaltenes in each section. The extraction results confirmed that the observed permeability impairment was indeed caused by asphaltene deposition in the middle and latter sections of the coil, where the pressure was less than the AOP. With the success of this experiment, the same detailed analysis can be extended to a series of experiments to determine the effects of different key parameters on pressure-induced asphaltene impairment, including flow rate, wettability, and permeability.

scholarly journals Behaviour of eccentrically inclined loaded rectangular foundation on reinforced sand

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sujata Gupta ◽  
Anupam Mital
Keyword(s):  
Bearing Capacity ◽  
Loading Conditions ◽  
Test Results ◽  
Bearing Capacity Ratio ◽  
Reinforced Sand ◽  
The Core ◽  
Capacity Ratio ◽  
Core Boundary ◽  
Rectangular Foundation ◽  
Increasing Load

Abstract This study presents the behaviour of model footing resting over unreinforced and reinforced sand bed under different loading conditions carried out experimentally. The parameters investigated in this study includes the number of reinforced layers (N = 0, 1, 2, 3, 4), embedment ratio (Df /B = 0, 0.5, 1.0), eccentric and inclined ratio (e/L, e/B = 0, 0.05, 0.10, 0.15) and (a = 0°, 7°, 14°). The test sand was reinforced with bi-axial geogrid (Bx20/20). The test results show that the ultimate bearing capacities decrease with axial eccentricity and inclination of applied loads. The test results also show that the depth of model footing increase zero to B (B = width of model footing), an increase of ultimate bearing capacity (UBC) approximated at 93%. Similarly, the multi-layered geogrid reinforced sand (N = 0 to 4) increases the UBC by about 75%. The bearing capacity ratio (BCR) of the model footing increases with an increasing load eccentricity to the core boundary of footing; if the load eccentricities increase continuity, the BCR decreases. The tilt of the model footing is increased by increasing the eccentricity and decreases with increasing the number of reinforcing layers.

Investigation of Effective Mechanisms in Permeability Reduction Due to Asphaltene Deposition through Porous Media

2013 ◽  
Author(s):  
M. Khederzadeh ◽  
S. Ostadrezaei ◽  
Iran R. Kharrat ◽  
H. Bagherzadeh ◽  
S. Mahdavi ◽  
...  
Keyword(s):  
Porous Media ◽  
Permeability Reduction ◽  
Asphaltene Deposition

Effective Removal of Asphaltene Deposition in Metal-Capillary Tubes

SPE Journal ◽  
2016 ◽  
Vol 21 (05) ◽  
pp. 1747-1754 ◽  
Author(s):  
Sara M. Hashmi ◽  
Abbas Firoozabadi
Keyword(s):  
Organic Acid ◽  
Laboratory Scale ◽  
Asphaltene Precipitation ◽  
Aromatic Solvent ◽  
Benzene Sulfonic Acid ◽  
Chemical Treatments ◽  
Effective Removal ◽  
Dodecyl Benzene Sulfonic Acid ◽  
Asphaltene Deposition ◽  
Petroleum Fluid

Summary We describe asphaltene deposition and removal processes in metal capillaries. We induce asphaltene precipitation by adding an asphaltene precipitant, heptane, to a petroleum fluid. The mixture is then injected through a laboratory-scale capillary and allowed to deposit. We assess the reversal of the deposition by means of the use of two separate chemical treatments: (1) a strong organic acid surfactant and (2) an aromatic solvent. The strong organic acid surfactant, dodecyl benzene sulfonic acid (DBSA), was shown to completely dissolve asphaltenes by means of acid-base chemistry reactions at heteroatomic sites on the asphaltene molecules. We investigate the use of DBSA as an efficient removal agent, injecting it in a mixture of petroleum fluid after the deposit was already formed. An aromatic solvent, toluene, is also investigated in such a fashion to assess its ability in removing deposited asphaltenes. We find that DBSA can effectively remove asphaltene deposits within one pore-volume (PV) of injection and at concentrations roughly ten times less than that required by an aromatic solvent such as toluene. To the best of our knowledge, our current study is the first laboratory-scale investigation with surfactant chemicals to reverse asphaltene deposition in capillaries.

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