Improving oil recovery from shale oil reservoirs using cyclic cold nitrogen injection – An experimental study

Elwegaa, Khalid; Emadi, Hossein

doi:10.1016/j.fuel.2019.115716

Cited by 11 publications

(2 citation statements)

References 13 publications

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“…Most of the reported studies of cyclic injection enhanced oil recovery (EOR) were implemented extensively using CO 2 in shale and tight reservoirs − and others used lean gas, methane, rich gas, or gas mixture. − Very little research was conducted using cyclic N 2 injection. − Yu and Sheng conducted an experimental study using N 2 and Eagle Ford shale cores. They soaked the cores in mineral oil before conducting the experiments.…”

Section: Introductionmentioning

confidence: 99%

Asphaltene Precipitation and Deposition during Nitrogen Gas Cyclic Miscible and Immiscible Injection in Eagle Ford Shale and Its Impact on Oil Recovery

Elturki

Imqam

2022

Energy Fuels

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Cyclic gas injection methods have been shown to improve oil recovery in conventional reservoirs. Even though similar technologies have been used in unconventional reservoirs with some success stories in shale resources, cyclic gas injection enhanced oil recovery (EOR) is still a little-understood subject in boosting oil recovery from unconventional reservoirs. During gas injection, asphaltenes start to deposit and precipitate, which causes pore plugging and reduces oil recovery. Studies of asphaltene deposition challenges during cyclic nitrogen (N 2 ) gas injection and oil production in unconventional reservoirs are yet relatively limited. Therefore, a comprehensive experimental study was conducted using 12 Eagle Ford shale cores (dynamic mode), and filter paper membranes (static mode) were used to evaluate whether miscible and immiscible huff-n-puff (cyclic) N 2 injection increases oil recovery and aggravates asphaltene precipitation. To ensure that miscibility can be examined in cyclic experiments, N 2 minimum miscibility pressure (MMP) was determined using a slim tube technique. The factors studied included the injection pressure, number of cycles, production time, and injection cyclic mode, all conducted at 70 °C. The findings showed that a high asphaltene weight percent was calculated during static experiments (i.e., using filter membranes), and this increase was severe on smaller pore size structures. Dynamic tests (i.e., using shale cores) showed that miscibility increased oil recovery, but a stronger intermediate-wet system was observed when measuring the wettability of cores after N 2 cyclic tests. When starting with shorter soaking times, more oil recovery could be achieved. Oil recovery reduction and asphaltene depositions were observed at later cycles. Microscopy and scanning electron microscopy (SEM) imaging of the Eagle Ford cores showed asphaltene clusters inside the cores after cyclic tests. A mercury porosimeter emphasized the degree of pore plugging after cyclic tests, and the findings revealed a smaller pore size distribution after N 2 tests due to the asphaltene deposition process when compared to cores that had not been pressured. This extensive study focuses on the effects of asphaltene deposition on oil recovery under cyclic N 2 -miscible and immiscible conditions in shale resources.

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Section: Introductionmentioning

confidence: 99%

Asphaltene Precipitation and Deposition during Nitrogen Gas Cyclic Miscible and Immiscible Injection in Eagle Ford Shale and Its Impact on Oil Recovery

Elturki

Imqam

2022

Energy Fuels

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“…For the rock mechanics parameter method, Rickman et al (2008) and Goodway et al (2010) believed that the rock brittleness index was closely related to Young's modulus and Poisson's ratio, and the brittleness would become greater when the Young's modulus gets larger and the Poisson's ratio gets smaller [3,5]; Liu and Sun (2015) and Bai (2016) considered that different minerals have different brittleness, and they constructed a new elastic parameter, i.e., brittleness factor, which could better explain the brittleness change in reservoir rocks [6,7]. For the stressstrain method, the stress-strain curve of the rock which reflects the whole process of rock deformation, cracking, and ultimate loss of bearing capacity under external load is the most intuitive and effective method for qualitative evaluation of rock brittleness [8][9][10]. Jin et al (2014), Bishop (1967), Tarasov and Potvin (2013), Munoz et al (2016), and Ge et al (2020) constructed the evaluation models of reservoir brittleness index based on their understandings of the stress-strain curve [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Study on a New Rock Fracability Evaluation Model of Shale Gas Reservoir

Wang

Zhang

et al. 2020

Geofluids

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Shale gas is an important unconventional energy resource that needs large-scale fracturing to form industrial deliverability. The evaluation of reservoir fracability plays a key role in the optimization of the sweet spot, the design of multistage fracturing, and the prediction of economic benefit. Based on volumetric fracturing, the study proceeded from the fracture complexity of the fractured core, and the bursting pressure experiment technology using the constant strain rate method was established. After the core has fractured, the fracture morphology was extracted and the fracture parameters including fracture area ratio and fracture declination dispersion were calculated to construct the fracture complexity of the pressed core. Combined with the core strength, the fracability index of the core was determined to evaluate the reservoir fracability. This method can represent not only the fracturing effect but also the fracturing difficulty. Compared with the monitoring data of hydrofracture-induced microseism of the sample well, the core fracturing index was found to be in good agreement with the actual fracturing effect. This method is more reasonable than the traditional brittleness index method and rock mechanics parameter method.

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Effect of Liquid Nitrogen Freezing on the Mechanical Strength and Fracture Morphology in a Deep Shale Gas Reservoir

et al. 2022

Rock Mech Rock Eng

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Improving oil recovery from shale oil reservoirs using cyclic cold nitrogen injection – An experimental study

Cited by 11 publications

References 13 publications

Asphaltene Precipitation and Deposition during Nitrogen Gas Cyclic Miscible and Immiscible Injection in Eagle Ford Shale and Its Impact on Oil Recovery

Asphaltene Precipitation and Deposition during Nitrogen Gas Cyclic Miscible and Immiscible Injection in Eagle Ford Shale and Its Impact on Oil Recovery

Study on a New Rock Fracability Evaluation Model of Shale Gas Reservoir

Effect of Liquid Nitrogen Freezing on the Mechanical Strength and Fracture Morphology in a Deep Shale Gas Reservoir

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