بررسی مکانیسم نفوذ ملکولی طی تزریق CO2 و گاز هیدروکربنی در بلوک منفرد و مدل سکتوری مخزن شکافدار

نوع مقاله: مقاله پژوهشی

نویسندگان

دانشکده مهندسی شیمی، دانشگاه علم و صنعت ایران، تهران، ایران

چکیده

تزریق گاز یکی از روش‌های معمول در ازدیاد برداشت از مخازن شکافدار است. بخش عمده‌ای از مخازن هیدروکربوری ایران شکافدار هستند. مکانیسم‌های تولیدی در مخازن شکافدار با مخازن معمولی متفاوت است. یکی از مکانیسم‌های تولیدی در مخازن شکاف‌دار تحت تزریق گاز، نفوذ مولکولی است که در کنار ریزش ثقلی می‌تواند بازیافت نفت را افزایش دهد. در این مطالعه با استفاده از شبیه‌سازی ترکیبی، تأثیر نفوذ مولکولی در بازیافت نفت طی تزریق CO2 و گاز هیدروکربوری رقیق، ابتدا در مقیاس بلوک ماتریس منفرد و سپس در سکتور مدل مربوط به یکی از مخازن جنوب غربی ایران بررسی‌شده است. ابتدا تأثیر نفوذپذیری ماتریس، اختلاف نفوذپذیری ماتریس و شکاف، تخلخل، فشار موئینگی گاز-نفت، ارتفاع ماتریس و ترکیب گاز تزریقی بر نفوذ مولکولی در بلوک ماتریس منفرد و سپس تأثیر نفوذ ملکولی در بازیافت نفت از سکتور مدل مخزنی در تزریق CO2 و گاز رقیق بررسی شد. نتایج نشان داد که نفوذ مولکولی با افزایش سرعت انتقال جرم بین ماتریس و شکاف در تزریق گاز امتزاجی (گاز رقیق و CO2) میزان بازیافت نفت را افزایش می‌دهد. هرچه نفوذپذیری ماتریس کمتر و فشار موئینگی گاز-نفت درون ماتریس بیشتر باشد، بازده جابجایی نفت در طی مکانیسم ریزش ثقلی کمتر می‌شود و تأثیر نفوذ مولکولی در بازیافت نهایی افزایش می‌یابد. در تزریق گاز در سکتور مخزن، در نظر گرفتن نفوذ مولکولی با به تأخیر انداختن زمان میان شکنی گاز از طریق جابجایی اجزاء به درون ماتریس و در نتیجه حفظ فشار مخزن میزان بازیافت نهایی را در تزریق CO2 حدود 2% و در تزریق گاز رقیق 5% افزایش می‌دهد.
 

کلیدواژه‌ها


عنوان مقاله [English]

Molecular Diffusion Investigation During CO2 and Hydrocarbon Gas Injection in a Single Matrix Block and a Fractured Reservoir Sector Model

نویسندگان [English]

  • Ahad Freydooni
  • Mehdi Assareh
  • Mehdi Assareh
Thermodynamics Research Laboratory, School of Chemical Engineering, Iran University of Science and Technology
چکیده [English]

One of the common methods of enhanced oil recovery in naturally fractured reservoirs is gas injection. The majority of Iranian hydrocarbon reservoirs are fractured reservoirs. Producing mechanisms is different in fractured reservoirs in comparison with conventional reservoirs. Molecular diffusion is one of the mechanisms that along with gravity drainage can increase oil recovery in fractured reservoirs during gas injection. In this work, the effect of molecular diffusion in CO2 and hydrocarbon gas injection as an EOR (enhanced oil recovery) process is investigated using compositional simulation in a single matrix block and a sector model of an Iranian natural fractured reservoir. The effect of the matrix permeability, matrix and fracture permeability difference, matrix porosity, matrix gas-oil capillary pressure and injection gas composition are checked in single matrix blocks, and then the influence of diffusion is investigated on the recovery of the sector model during the CO2 and hydrocarbon gas injection. The results show that molecular diffusion raises oil recovery by increasing the mass transfer rate between the matrix and fracture during miscible gas injection (CO2 and hydrocarbon gas). The low matrix permeability and high gas-oil capillary pressure within the matrix oil make smaller displacement efficiency during gravity drainage. In the sector model, the molecular diffusion increases the ultimate oil recovery by about %2 and %5 in CO2 and hydrocarbon gas injection, respectively by delaying gas breakthrough in an production well and maintaining reservoir pressure.

کلیدواژه‌ها [English]

  • Fractured Reservoirs
  • Gas Injection
  • Molecular Diffusion
  • Single Matrix Block

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