Oil & Gas Geology ›› 2019, Vol. 40 ›› Issue (3): 669-677.doi: 10.11743/ogg20190322

• Petroleum Development and Engineering • Previous Articles     Next Articles

Fracture extension and distribution pattern of volume fracturing in tight reservoir: An analysis based on actual coring data after fracturing

Niu Xiaobing1,2, Feng Shengbin1,2, You Yuan1,2, Liang Xiaowei1,2, Xin Honggang1,2, Dan Weidong1,2, Li Tingyan1,2, Ren Jisheng3   

  1. 1. Exploration and Development Research Institute of Changqing Oilfield Company, PetroChina, Xi'an, Shaanxi, 710018, China;
    2. National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields, Xi'an, Shaanxi 710018, China;
    3. No.2 Mud Logging Branch Company, CNPC Bohai Drilling Engineering Co., Ltd., Renqiu, Hebei, 062550, China
  • Received:2019-02-15 Revised:2019-03-27 Online:2019-06-28 Published:2019-04-26

Abstract: The extension and distribution of hydraulic fractures in stimulated reservoir volume (SRV) after volume fracturing are the key for unconventional oil and gas exploration and development.The artificial fractures created in reservoirs after volume fracturing were identified and characterized based on the actual coring data,logging data and laboratory data of the coring wells completed in the tight oil pilot area of the Ordos Basin.Subsequently,the development characteristics of artificial fractures in the simulated reservoir volume (SRV) were analyzed,and the effective extension and spatial distribution of the hydraulic fractures were discussed.The results show that under volume fracturing,the nearly vertical extensional mirco-fractures of 0.13 m in length were created in the oil-bearing massive sandstones in the Chang 7 of the tight oil pilot zone X233,and many bedding-parallel or -crossing fractures were observed in oil layers about 1.49 m away from the operational area.Hydrocarbon extravasation along these fractures is significant,indicating that they are the artificial fractures generated by fracturing.By comprehensive analysis,we found that a hydraulic fracture network consists of limited number of main fractures,a large number of micro-fractures generated and bedding-parallel fractures extended or expanded by fracturing.Meanwhile,the extension range of macro-fracture network in the SRV is limited,but the micro-fractures are widely developed,and the remaining oil saturation of the reservoir stays high,all of which indicate that there is still room to optimize the volume fracturing technology for tight oil reservoir.

Key words: micro-fracture, hydraulic fracture, volume fracturing, reservoir, tight oil, the 7th member of the Yanchang Formation, Ordos Basin

CLC Number: