Research on Flow Mechanism of Fishbone Well in Heavy Oil Field and Evaluate Its Development in Bohai Bay Heavy Oil Fields

• Published in: Physical and Numerical Simulation of Geotechnical Engineering no. 24; p. 84
• Main Authors: Yingchun, Zhang, Chunming, Zhao, Kaijun, Tong, Fengjun, Zhou
• Format: Journal Article
• Language: English
• Published: Brighton East St. Plum-Blossom Press Pty Ltd 01.09.2016
• Subjects: Efficiency; Exploitation; Mathematical models; Oil field equipment; Oil fields; Productivity; Recovery; Wells; INW, Bohai Sea, Bohai Bay
• ISSN: 1838-3254; 2204-2040

Bohai Bay heavy oil fields are characterized by low productivity. According to above character, the heavy oil area of SZ 36-1 oilfield is chosen for a pilot area which aimed at improving both well productivity and ultimate recovery efficiency. Based on the existing inverted nine-spot pattern, five multilateral wells are located in the stably distributed and relatively thicker pay zones where put into production along with those existing directional wells. In this paper, we research on the mechanism of the heavy oil flow in porous medium. Firstly, based on analyzing the mathematical characterization of horizontal segment and branch, the production model of the symmetrical and unsymmetrical fishbone well is established using the principle of potential superposition and infinitesimal congruence, and involving the interference between branches. Secondly, using the above fishbone well mode design of fishbone well is optimized, including the length and number of benches, the distance between horizontal wall and branch, and the well is optimized on account of the well network. These five fishbone well were successfully exploited in Bohai bay heavy oilfield, which obtained satisfactory exploitation effect. The productivity of the fishbone wells is as high as 90-150 m3/d, which is 6-8 times of that a directional well. Reservoir simulation result shows that the pilot area's ultimate recovery efficiency increment would reach as much as 4%. The exploitation of these five fishbone well in pilot area made a successful example to exploit heavy oilfields. The project has now been extended in other heavy oilfields in Bohai bay. Twenty-eight fishbone wells have been put into production. According to the exploitation effect, it not only could enhance the production, but also could enhance ultimate recovery efficiency. The development pattern combining the direction well with the fishbone well is an efficient pattern to exploit heavy oilfields.