Experimental Study and Field Application of Fiber Dynamic Diversion in West China Ultra-Deep Fractured Gas Reservoir

Fu, Haifeng (Petrochina Research Insitute of Petroleum Exploration and Developement) | Yan, Yuzhong (Petrochina Research Insitute of Petroleum Exploration and Developement) | Xu, Yun (Petrochina Research Insitute of Petroleum Exploration and Developement) | Liang, Tiancheng (Petrochina Research Insitute of Petroleum Exploration and Developement) | Liu, Yunzhi (Petrochina Research Insitute of Petroleum Exploration and Developement) | Guan, Baoshan (Petrochina Research Insitute of Petroleum Exploration and Developement) | Wang, Xin (Petrochina Research Insitute of Petroleum Exploration and Developement) | Weng, Dingwei (Petrochina Research Insitute of Petroleum Exploration and Developement) | Feng, Jueyong (Tarim Oilfield Company)

OnePetro 

ABSTRACT: Although a new technology of fiber diversion was introduced to hydraulic fracturing for ultra-deep sandstone formation, the operation is not always effective. This paper focused on the fracture reorientation mechanism and the relationship between injection pressure and fracture diversion according to large-scale physical simulation for fiber diversion in lab. The test results show that: firstly, the volume of fiber-based fluid is an important factor affecting fracturing diversion. If less fluid is designed, it would block original fractures inadequately. On the other hand, more fiber will result in sealing the open hole completely and fail to generate fracture diversion. Secondly, fracture initiation pressure after fiber frac fluid pumping can be used to evaluate diversion effectiveness. Higher level means lager reorientation angle. In the two-stage perforation, two fractures are initiated at different perforated wellbore depths. This validates the technology of fiber fracturing to create a better vertical coverage in the thick layer without mechanical packer. What we can learn from test results will help guide fiber diversion designing and evaluate corresponding fracture network in ultra-deep reservoir where great production contributed to natural fracture system, for example Dabei and Keshen gas fields in the Tarim Basin located in Western China.

1. INTRODUCTION

There are amounts of natural gas reserve in ultra-deep (more than 6000m) sandstone reservoir in Western China, especially in Tarim Basin[1]. However, due to some extreme geological conditions, great challenges exist in hydraulic fracturing to develop this kind of reservoir successfully[2-6]. Firstly, the traditional fracturing tools, such as fracturing packer and sliding sleeve, maybe not work effectively under the environment with high pressure(between15000psi and 20000psi), high temperature (between160° and 170°). Secondly, although the effective layer is very thick(between 100m and 300m), the internal vertical heterogeneity is very serious. So it is hard to create a better vertical coverage in the formation with fracturing. Thirdly, the natural fracture distribution is very complex due to active tectonic stress in this area. It is a favorable factor contributing to the improvement of reservoir permeability and gas production[7].On the other hand, it is also the main factor of the sand screen out which results in stimulation treatment failure[8]. So fracturing technology for communicating with more natural fractures would be optimized to improve stimulated reservoir volume(SRV).