Sains Malaysiana 44(5)(2015): 719–725

Experimental Study on Permeability Stress Sensitivity in Tight Sandstone Oil Reservoirs

(Kajian Eksperimen ke atas Kepekaan Tegasan Ketelapan dalam Reservoir Minyak Batu Pasir Padat)

XIAOFENG TIAN¹*, LINSONG CHENG¹, WENQI ZHAO¹, YIQUN YAN¹, XIAOHUI HE¹ & QIANG GUO²

¹Petroleum Engineering Department, China University of Petroleum

102249 Beijing, China

²Missouri University of Science and Technology, 65409 Missouri, United States of America

Diserahkan: 10 Disember 2013/Diterima: 8 Januari 2015

ABSTRACT

In this paper, seven permeability stress sensitivity experiments were conducted to show the features of permeability stress sensitivity. The cores in the experiments were taken from the tight sandstone oil reservoir in Ordos Basin. Then advanced technologies, such as casting thin section, scanning electron microscope and rate-controlled mercury penetration, were applied to explain the mechanism of permeability stress sensitivity in tight oil reservoirs. The results indicated that the permeability reduction and recovery in gas permeability stress sensitivity increases as the permeability decreases. This was resulted from the maximal throat radius. The permeability reduction in liquid permeability stress sensitivity increases at first and then decreases as the permeability decreases. The permeability recovery decreases to zero as the permeability decreases. Additionally, the differences between gas and liquid permeability stress sensitivity become greater as the permeability decreases. These were resulted from the effect of the critical throat radius. This paper corrects the mistakes about the stress sensitivity in tight oil reservoirs from gas permeability stress sensitivity experiments which is significant to the development of tight sandstone oil reservoirs.

Keywords: Critical throat; permeability stress sensitivity; throat distribution; tight sandstone oil reservoir

ABSTRAK

Dalam kertas ini, tujuh uji kaji kadar resapan tekanan kepekaan telah dijalankan untuk menunjukkan ciri kepekaan tegasan ketelapan. Teras dalam uji kaji ini telah diambil dari reservoir minyak batu pasir padat di Lembangan Ordos. Selepas itu, teknologi yang lebih maju seperti pemilihan irisan nipis, mikroskop elektron imbasan dan penembusan merkuri tahap-dikawal digunakan untuk menerangkan mekanisme kepekaan tegasan ketelapan dalam reservoir minyak yang padat. Keputusan menunjukkan pengurangan ketelapan dan perolehan dalam gas kepekaan tegasan ketelapan meningkat apabila ketelapan berkurangan. Ini adalah akibat daripada jejari keluk maksimum. Pengurangan ketelapan dalam cecair kepekaan tegasan ketelapan pada mulanya meningkat dan kemudian penurunan apabila ketelapan berkurangan. Ketelapan perolehan menurun kepada sifar apabila ketelapan menurun. Di samping itu, perbezaan antara gas dan cecair kepekaan tegasan ketelapan menjadi lebih besar apabila ketelapan menurun. Ini disebabkan kesan daripada jejari keluk yang kritikal. Kertas ini membetulkan kesilapan tentang kepekaan tegasan dalam reservoir minyak yang padat daripada eksperimen kepekaan tegasan ketelapan gas yang penting kepada pembangunan reservoir minyak batu pasir yang padat.

Kata kunci: Keluk kritikal; kepekaan tegasan ketelapan; pengagihan keluk; reservoir minyak batu pasir padat

RUJUKAN

Baohong, S., Yan, Z., Lei, Z., Yajuan, Y. & Hui, L. 2012. Hydrocarbon accumulation dating by fluid inclusion characteristics in Chang7 tight sandstone reservoirs of Yanchang Formation in Ordos Basin. Petroleum Geology & Experiment 34(6): 599-603.

Caineng, Z., Rukai, Z., Bin, B., Zhi, Y., Songtao, W. & Ling, S. 2011. First discovery of nano-pore throat in oil and gas reservoir in China and its scientific value. Acta Petrologica Sinica27(6): 1857-1864.

Fatt, I. & Davis. D.H. 1952. Reduction in permeability with overburden pressure. Journal of Petroleum Technology 4(12): 16.

Fatt, I. 1958. Pore volume compressibilities of sandstone reservoirs rocks. Journal of Petroleum Technology 42(8): 64-66.

Jones, S.C. 1988. Two-point determinations of permeability and PV vs net confining stress. SPE Formation Evaluation 3: 235-241.

Jose, G. 1997. Numerical simulation of coupled fluid-flow/ geomechanical behavior of tight gas reservoirs with stress sensitive permeability. Brazil. Latin American and Caribbean Petroleum Engineering Conference.

Junchang, S., Zhengming, Y. & Qi, T. 2013. Comparative study on stress-dependent permeability of ultra-low permeability sandstone rock using different types of fluid media. China. International Petroleum Conference.

Latchie, A.S.M., Hemstick, R.A. & Joung, L.W. 1958. The effective compressibility of reservoir rock and its effect on permeability. Journal of Petroleum Technology 10(6): 49-51.

Ruilan, L., Linsong, C., Jianchun, P. & Huayin, Z. 2007. A new method of determining relationship between permeability and effective overburden pressure for low-permeability reservoirs. Journal of China University of Petroleum (Natural Science Edition) 31(2): 87-90.

Terzaghi, K. 1943. Theoretical Soil Mechanics. New Jersey: John Wiley & Sons Inc. pp. 11-15.

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