Sains Malaysiana 45(10)(2016): 1579–1587

A New Model to Predict the Unsteady Production of Fractured Horizontal Wells

(Model Baharu untuk Meramalkan Pengeluaran tak Menentu Telaga Mendatar yang Retak)

FANHUI-ZENG*, XIAOZHAO-CHENG, JIANCHUN-GUO, CHUAN LONG & YUBIAO-KE

State Key Laboratory of Oil and Gas Geology and Exploration, Southwest Petroleum University

610500, Chengdu, P.R. China

Received: 2 July 2015/Accepted: 7 March 2016

ABSTRACT

Based on the hydraulic fracture width gradually narrows along the fracture length, with consideration of the mutual influences of fracture, non-uniform inflow of fractures segments and variable mass flow in the fracture comprehensively, a spatial separation method and time separation method were used to establish fracture horizontal well’s dynamic coupling model of reservoir seepage and fracture flow. The results showed that the calculation productivity of variable width model is higher than that of the fixed width model, while the difference becomes smaller as time increase. Due to mutual interference of the fractures, the production of outer fracture is higher than that of the inner fracture. When the dimensionless fracture conductivity is 0.1, the middle segment of the fracture dominates the productivity and local peak emerges near the horizontal well. The flow in the fracture is with the ‘double U’ type distribution. As the dimensionless fracture conductivity increase, the fractures productivity mainly through the tips and the flow in the fractures with the ‘U’ type distribution. Using the established fracture width variable productivity prediction model, one can achieve the quantitative optimization of fracture shape.

Keywords: Fractured horizontal well; fracture shape quantitative optimization; flux distribution; unsteady productivity; variable fracture width

ABSTRAK

Berdasarkan lebar retak hidraulik beransur-ansur sempit sepanjang kepanjangan retak, dengan pertimbangan retak pengaruh bersalingan, aliran masuk segmen retak tak seragam dan pemboleh ubah aliran jisim dalam retak secara menyeluruh, kaedah pemisahan reruang dan masa telah digunakan untuk menubuhkan model gandingan dinamik telaga melintang retak aliran takungan tirisan dan retak. Keputusan kajian menunjukkan bahawa produktiviti pengiraan model kelebaran berubah-ubah adalah lebih tinggi daripada model dengan kelebaran tetap, namun perbezaan menjadi lebih kecil dengan peningkatan masa. Disebabkan keretakan gangguan itu bersalingan, penghasilan retak bahagian luar adalah lebih tinggi daripada retak dalaman. Apabila konduktiviti retak tanpa dimensi adalah 0.1, segmen tengah retak menguasai produktiviti dan puncak tempatan muncul berhampiran telaga mendatar. Aliran dalam retakan adalah dengan taburan jenis ‘dua U’. Semasa konduktiviti retak tanpa dimensi meningkat, produktiviti retak terutamanya menerusi aliran hujung dan dalam retak bersama dengan taburan jenis ‘U’. Dengan menggunakan model peramalan produktiviti retak lebar pemboleh ubah yang ditubuhkan, pengoptimuman kuantitatif bentuk retak boleh dicapai.

Kata kunci: Kelebaran retak pemboleh ubah; pengoptimuman kuantitatif bentuk retak; produktiviti tak menentu; taburan fluks; telaga mendatar yang retak

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*Corresponding author; email: zengfanhui023024@126.com