Journal of Southwest Petroleum University(Science & Technology Edition) ›› 2024, Vol. 46 ›› Issue (5): 1-18.DOI: 10.11885/j.issn.1674-5086.2022.10.18.04

• GEOLOGY EXPLORATION •     Next Articles

Application of Fracturing Construction Curve in Fracture Evaluation of Deep Shale Gas Horizontal Wells

YAN Jianping1,2,3, LAI Siyu1,2, GUO Wei4, LIAO Maojie5, HUANG Yi6   

  1. 1. School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    2. Natural Gas Geology Key Laboratory of Sichuan Province, Chengdu, Sichuan 610500, China;
    3. State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    4. Research Institute of Petroleum Exploration & Development, PetroChina, Haidian, Beijing 100083, China;
    5. Research Institute of Shale Gas, Southwest Oil & Gasfield Company, PetroChina, Chengdu, Sichuan 610000, China;
    6. Southwest Branch, CNPC Logging Company Limited, Yubei, Chongqing, 400021, China
  • Received:2022-10-18 Published:2024-11-07

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Abstract: Shale gas horizontal wells usually do not have coring and electrical imaging scales, which makes it difficult to identify fractures. The fracturing operation curve can reflect the fracturing effect and the development of natural fractures before fracturing. Taking the deep shale gas formation of Block Y101 in Luzhou, southern Sichuan as an example, according to the type and characteristics of the fracturing operation curve in the sand-carrying fluid stage, the logging response characteristics of the fracture layer and the matrix layer before the fracturing of the horizontal well are calibrated. The wavelet transform is used to extract the high-frequency weak signal reflecting the fracture information to establish the wavelet comprehensive coefficient (WI), the crossplot is used to select six parameter indexes sensitive to the fracture response, the analytic hierarchy process and the fuzzy mathematics method are used to construct the fracture evaluation comprehensive coefficient (FI), and the relationship between different fracturing operation curve types and logging information is further combined to realize the identification and development level evaluation of horizontal well fracture layers. The results show that the fracturing construction curve of the sand-carrying fluid stage has a descending type (I), a descending stable type (II), a stable type (III), and an ascending type (IV). Among them, when the natural gamma high value, the compensated neutron and the density increase significantly, the acoustic time difference increases with the “jagged” cycle jump, the double lateral shows a “positive difference” and WI≥0.18，FI≥0.430, the fracturing construction curve is a descending type, and the fracture is well developed (F–A grade); When 0.390≤FI<0.430, there are both downward type and downward stable type, and the fractures are more developed (F–B grade); when 0.350≤FI<0.390, it is a descending stable type, and the fractures are generally developed (F–C grade).

Key words: deep shale gas, horizontal well, fracturing operation curve, fracture evaluation, logging information

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