Abstract

Liquids rich shale production has gained prominence in recent years. The advent of horizontal drilling, coupled with multi-stage transverse fracturing has allowed for the economic recovery of hydrocarbons. Recovery in liquids rich unconventional reservoirs are challenging because these wells could face productivity loss over time due to liquid loading in the wellbore. Various researchers have addressed liquid loading issues in a horizontal wells and prediction of well performance under such conditions (Denney, 2012; Kamkom et. al. 2009; Shu, 2013). To maximize the returns and net present value (NPV) it is critical to consider wellbore orientation when developing these reservoirs. This paper addresses possible impacts of toe-up or toe-down orientation to the well productivity and its overall economic impact. An in-depth integrated analysis of lateral Total Vertical Depth (TVD) change, i.e., the change from the heel to the toe of a horizontal well (toe up vs toe down) on horizontal multi-fractured well production performance (IP 90s, 365 Day Cumulative Totals, EURs) in the Cana Woodford play of west central Oklahoma. This analysis used a 300+ well dataset contained within a three township area to isolate well production performance drivers such as reservoir conditions, geology, stimulation size, etc.

A dataset of this size contained within a small homogenous area allows for superior statistical control and results. The analysis used a real world dataset to create isolated variable groups, so that the affect of change in lateral TVD on production could be analyzed independent of other factors. From the analysis a relationship between lateral TVD change and production performance was seen. Impact of the relationship also changed based on the reservoir conditions. In the analyzed dataset lateral TVD change showed to have a significant effect on production performance. The analysis indicates, Toe-Down wells were the lowest performing group, followed by flat wells, then Toe-Up wells. Not only were Toe-Down wells poor performers but the more severe the inclination angle ("Toe-Downess") the poorer the production performance. Toe Up vs Toe Down may or may not have an impact on the well performance over time depending on the horizontal play/ reservoir conditions but it is important to identify if it is a factor. If Toe-Up vs Toe-Down is found to be a controlling factor on production performance actions can be taken to maximize production by changing developmental and geo-steering strategies in the play therefore increasing incremental economics.

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