While the Mississippi Lime (or more accurately the Mississippian Lime, since it refers to a subperiod of geologic time) play has been commercial for decades through vertical well development, today we will analyze recent horizontal well production and drilling trends.
What is The Mississipian Lime?
The Mississippian Lime consists of a number of various formations that are Mississippian in age (~320 – 360 mya). Lithology varies throughout the entire stratigraphic interval, and lithological features include fine-grained limestones, argillaceous muds, spiculites, tripolites and chert.
The Mississippian section is roughly 500 feet thick and consists of various reservoir facies that require specific completion design and stimulation, due to differing porosity systems. Therefore, it’s crucial to know the lithology of play.
The purpose of this post is to examine the sweet spots of the play and get a better understanding of optimal target of penetration.
Let’s Look at Some Data
For normalization purposes, I decided to dissect the core area of the play into east and west regions split by the Nemaha Uplift. Also, I split out the Mississippian interval by upper and lower sections for further comparison, using TVD. While lithology is analogous on opposite sides of the uplift, there are still major structural differences. The primary difference between the eastern and western core areas is the variation in gas to oil ratio. Observe the chart and map (only horizontal wells shown) below:
The cross section below, courtesy of Vitruvian Exploration, sheds a little light on the reason behind this phenomenon. Similar to the Nesson Anticline of the Williston Basin, structural basement features play an important role on diagentic processes and thermal maturity.
The next data point of interest is the target interval for horizontal wellbores. The map below shows horizontal wellbores only and whether the lateral penetrates the upper or lower Mississippian Lime sequence.
Where Should We Drill?
Based on these data findings
- The east is more prospective for oil (with its lower GOR), but
- the west holds more promise for optimal production with it’s abundant lower Mississippian Lime, the objective zone of penetration.
Therefore, the deeper section on the western side of the core area is the best sweet spot area in terms of production.
The caveat here is to take into account rate of return. Deeper wells cost more money to drill. This makes for a very interesting play. Not only is the geology complex, but the economics become just as much a challenge.
Sandridge Energy reports their well costs at about $3MM, with an EUR of 369 Mboe; ultimately providing an IRR of 45%. Even though the production volumes of these Mississippian Lime wells may not be as high as other horizontal unconventional resource plays, the cheaper well costs still allow for solid returns.
There is a Lot More to Learn About the Mississippi Lime, er, Mississipian Lime Play
Stay connected to the DI Blog for a follow up on the Mississippian Lime play and the topic of salt water disposal wells.
What do you think? What are your expectations for the Mississippian Lime Play? Leave a comment below.
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