Abstract
In a challenging price environment, developing unconventional plays requires a relentless effort at improving operations practices. However, comparing the impact of different completion designs or well management strategies on well performance remains a challenge due to these plays relatively brief production history and lack of long-term field analogs. This study examines various production durations as potential candidates for reliable indicators of well quality. A reservoir modeling approach for unconventional plays is time consuming and may not properly simulate the complex interaction between subsurface properties and operational strategy. Assessment based on early production may be misleading due to well clean–up issue while comparison based on long-term well performance is inappropriate for quick decision making. This is an approach to find an optimum production duration for performance indicator, early enough to be useful and late enough not to be impacted by wells’ clean-ups. The workflow was developed then tested on Utica Shale unconventional play in Ohio, USA, and using data from 676 producing wells. The results show that predictions of midterm performance start to be reliable only near 180 days of cumulative well production. This study used actual daily production data to confirm that IP-30 days and IP-90 days are not strongly correlated to well actual performance in two year range. It also gives validation for the concept of use of 180-days to 360-days performance as more reliable indicators of well quality. The identification of a reliable quality indicator is a critical first component for any subsequent analysis attempting to identify the underlying factor controlling productivity. This study illustrates the danger inherent in the commonly used industry practice of quantifying well quality based on early production. In particular it shows that the first 30 days of production has almost no correlation with longer term production life.
