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Quantifying Matrix and Fracturing Water Contributions to the Total Produced Water Based on the Water-flowback Responses

  • Author / Creator
    Liu, Zhanyuan
  • The main goal of this thesis is to evaluate the possibility of quantifying matrix and fracturing water contributions to the total produced water based on the water-flowback responses without analyzing water chemical data. We analyze flowback production data of 380 multi-fractured horizontal oil wells completed in the Montney Formation and 90 oil and gas wells completed in the Duvernay and Horn River formations. We hypothesize that: 1) the slope of water-flowback harmonic decline (HD) profiles (mHD) is proportional to the slope of rate-normalized pressure (RNP) plots (mRNP), and 2) both mRNP and mHD are inversely proportional to the amount of water influx from matrix into fractures. To verify our hypothesis, we 1) modify the previous HD and single-phase flowing material balance models by considering the water influx from matrix into fractures, 2) classify the studied wells based on observed trends, 3) construct RNP diagnostic plots of the studied wells, 4) investigate the relationship between mHD and mRNP, 5) analyze log data and estimate average initial water saturation (Swi) for the studied wells, and 6) investigate the relationship between of mHD and Swi. The results show that mHD for all the studied wells ranges from 0.00001 to 0.036 1/m^3 with a mean value of 0.0056 1/m^3. Wells with higher mHD have relatively higher mRNP values. In contrast, wells with very low mHD show no significant decline in water rate through the entire flowback process and relatively low or inconsistent mRNP values on the corresponding plots of RNP versus material balance time (MBT). We also observe a negative correlation between mHD and Swi obtained by analysis of wireline log data. This correlation and the positive correlation between mHD and mRNP indicate that as Swi increases, water influx from matrix to fracture increases, and thus, both mHD and mRNP decrease. Based on our modified models and the observed correlations, we develop a method to approximately differentiate between matrix and fracturing water. The applications of our heuristic method on field data shows 1) fracturing water production dominates the total water recovery for wells with higher mRNP, and 2) matrix water production dominates the total water recovery for wells with lower mRNP.

  • Subjects / Keywords
  • Graduation date
    Fall 2023
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.