An experimental investigation of improving Wolfcamp Shale-Oil recovery using Liquid-N2-assisted N2 and/or CO2 Huff-n-Puff injection technique

Altawati, Faisal; Emadi, Hossein; Khalil, Rayan; Heinze, Lloyd; Menouar, Habib

doi:10.1016/j.fuel.2022.124450

Cited by 18 publications

(9 citation statements)

References 56 publications

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“…Their study's weakness was that they employed mineral oil rather than crude oil, which ignores the influence of asphaltene precipitation on oil recovery. Altawati 71 saturated several Eagle Ford cores with decane oil and 15% NaCl brine water to study the effect of water saturation on oil recovery, utilizing the cyclic CO 2 and N 2 processes. The findings concluded that the partially saturated cores with water gave less recovery factor (RF) compared to cores with no water.…”

Section: Introductionmentioning

confidence: 99%

“…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%

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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%

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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“…Recently, gas huff-n-puff and flooding processes have been studied extensively in shale resources by various approaches, including experimental studies, − field pilots, , and simulation work. − Using N 2 and Eagle Ford shale cores, Yu and Sheng carried out an experimental investigation. They used mineral oil to saturate the cores and to perform the study.…”

Section: Introductionmentioning

confidence: 99%

“…There was a weakness in their research, however, since they did not utilize crude oil but mineral oil instead, so avoiding the impact of asphaltene precipitation on the performance of OR. To examine how water saturation influences OR using CO 2 and N 2 huff-n-puff processes, Altawati saturated Eagle Ford outcrops with oil of decane and brine with a percentage of 15%. Altawati discovered that cores that were slightly wet with water had a lower recovery factor (RF) than those that were not saturated with water.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Asphaltene Deposition and Its Impact on Oil Recovery in Eagle Ford Shale during Miscible and Immiscible CO₂ Huff-n-Puff Gas Injection

Elturki

Imqam

2023

Energy Fuels

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One of the challenges in extracting oil from unconventional resources using hydraulic fracturing and horizontal drilling techniques is the low primary recovery rate, which is caused by the ultra-small permeability of these resources. Consequently, it is essential to investigate gas injection methods to produce the trapped oil in shale formations. However, the injection process can cause asphaltene depositions inside the reservoir, leading to plugging of pores and oil recovery (OR) reduction. There has been limited research on using gas injection techniques to improve oil production in tight/unconventional resources, although carbon dioxide (CO2) and gas-enhanced oil recovery methods have been used in conventional resources. In order to determine whether or not the cyclic (huff-n-puff) CO2 process improves OR and aggravates asphaltene precipitation, a rigorous experimental investigation was undertaken utilizing filter membranes and Eagle Ford shale cores. After the minimum miscibility pressure was calculated for CO2, various injection pressures were selected to perform CO2 huff-n-puff experiments. Investigations were carried out at 70 °C on injection pressure, cycle number, production time, and huff-and-puff mode injection. The results demonstrated that when the pore size structure of the membranes used was smaller and gas injection cycles increased, a higher asphaltene weight percent (wt %) was determined during the static experiments (i.e., employing filter paper membranes). Miscibility improved OR in dynamic testing (i.e., using shale cores), but a more oil-wet system was detected in wettability measurements taken following CO2 huff-and-puff tests. The plugging impact of asphaltene particles on the pore structure was studied using optical microscopy and scanning electron microscopy imaging. Following the huff-and-puff tests, a mercury porosimeter revealed how severely the pores were plugged, and after the CO2 tests, the pore size distribution reduced as a consequence of asphaltene deposition. This study examines the significance of CO2 injection in OR under miscible/immiscible conditions to identify the critical parameters that could impact the effectiveness of CO2 huff-n-puff operation in unconventional formations.

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“…With the continuous expansion of exploration theory and the gradual improvement of development technology, unconventional oil and gas resources are gradually becoming a pillar of the energy industry. Recent studies have shown that the development of unconventional oil and gas is very promising. − Shale oil is one of the most important types of unconventional oil and gas resources and is often adsorbed, dissolved, or free in shale matrix pores, microfractures, and thin interlayers of nonhydrocarbon rocks and has typical characteristics of integrated source and storage. ,, According to different depositional environments and hydrocarbon source rock types, shales can be subdivided into marine shales and continental shales. Marine shales are predominant in North America, while continental shales are predominant in China .…”

Section: Introductionmentioning

confidence: 99%

Study on the Difference in CO₂ and Air Injection in the Fracture/Matrix Dual Medium of Continental Shale Reservoirs

Tan

Qin

et al. 2023

ACS Omega

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To clarify the impact of different displacement media on the enhanced oil recovery of continental shale and realize the efficient and reasonable development of shale reservoirs, this paper takes the continental shale of the Lucaogou Formation in the Jimusar Sag in the Junggar Basin (China, Xinjiang) as the research object and uses real cores to build the fracture/matrix dual-medium model. Computerized tomography (CT) scanning is used to visually compare and analyze the influence of fracture/matrix dual-medium and single-matrix medium seepage systems on oil production characteristics and clarify the difference between air and CO2 in enhancing the oil recovery of continental shale reservoirs. Through a comprehensive analysis of the production parameters, the whole oil displacement process can be divided into three stages: the oil-rich and gas-poor stage, oil and gas coproduction stage, and gas-rich and oil-poor stage. Shale oil production follows the rule of fractures first and matrix second. However, for CO2 injection, after the crude oil in the fractures is recovered, the oil in the matrix migrates to the fractures under the action of CO2 dissolution and extraction. Overall, the oil displacement effect of CO2 is better than that of air, resulting in a 5.42% higher final recovery factor. Additionally, fractures can increase the permeability of the reservoir, which can greatly enhance oil recovery in the early oil displacement process. However, as the amount of injected gas increases, its impact gradually decreases, and ultimately, it is consistent with the recovery of nonfractured shale, which can achieve nearly the same development effect.

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An experimental investigation of improving Wolfcamp Shale-Oil recovery using Liquid-N2-assisted N2 and/or CO2 Huff-n-Puff injection technique

Cited by 18 publications

References 56 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

Experimental Investigation of Asphaltene Deposition and Its Impact on Oil Recovery in Eagle Ford Shale during Miscible and Immiscible CO₂ Huff-n-Puff Gas Injection

Study on the Difference in CO₂ and Air Injection in the Fracture/Matrix Dual Medium of Continental Shale Reservoirs

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An experimental investigation of improving Wolfcamp Shale-Oil recovery using Liquid-N2-assisted N2 and/or CO2 Huff-n-Puff injection technique

Cited by 18 publications

References 56 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

Experimental Investigation of Asphaltene Deposition and Its Impact on Oil Recovery in Eagle Ford Shale during Miscible and Immiscible CO2 Huff-n-Puff Gas Injection

Study on the Difference in CO2 and Air Injection in the Fracture/Matrix Dual Medium of Continental Shale Reservoirs

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Experimental Investigation of Asphaltene Deposition and Its Impact on Oil Recovery in Eagle Ford Shale during Miscible and Immiscible CO₂ Huff-n-Puff Gas Injection

Study on the Difference in CO₂ and Air Injection in the Fracture/Matrix Dual Medium of Continental Shale Reservoirs