Factors Controlling Recovery in Liquids Rich Unconventional Systems

According to the U.S. Energy Information Administration (EIA), oil production in the United States reached 6.68 million barrels a day in November, 2012, its highest level since 1994. Development of hydrocarbons in deep unconventional formations via horizontal drilling and fracturing has been the main contributor to this growth. The two most impactful plays have been Bakken in North Dakota and Eagle Ford in Texas. While recognizing the success of unconventionals associated with high oil price and enhanced hydraulic fracture stimulation technologies, it is important to understand the development challenges and factors controlling recovery. The combination of limited drainage area and low resource density in unconventional systems has led to low recovery per well and challenging economics. Unconventional development has increasingly focused on liquids rich systems, especially in North America due to relatively low natural gas prices. The addition of liquids can improve overall economics, athough two phase flow impacts and complicates fluid flow and ultimate recovery. Performance of liquids rich systems is highly dependent on in-place fluid composition and phase behavior. Therefore, understanding liquids rich system phase behavior and its impact on performance is an important economic consideration. This paper discusses the drive mechanisms for unconventional plays ranging from dry gas to oil and the importance of geology and rock and fluid properties on rate and recovery. It specifically explores how the variation in liquid yield impacts rate and recovery.e