Well Placement

Your land has been leased. There is good reason to believe that there is oil on your land. Now how do the oil companies determine where the wells will go? That is an answer that is a combination of geological factors and suitable drill sites based on land position, and regulations.

Since the Niobrara is a self sourced reservoir, there are a couple of important factors that must be re-visited from the Niobrara Exploration Controls Section.

• We know the Niobrara formation is tight and oil only flows easily when fractured
• We know that your land was chosen because it is in the “oil window”
• We presume that seismic surveys have confirmed natural fracturing of the formation
• We know that horizontal drilling and fracking technology will be used to drain all the oil underneath the surface.

Now what are the main geologic factors that determine well placement and direction?

As you can see from the accompanying diagram, the main stress field present in Colorado and on the Niobrara due to Mountain Building is along a ~ 50 degree azimuth

Since Fractures that parallel this azimuth are the main fairway for oil flow (Merin and Moore, 1986), it only makes sense that horizontal wells oriented in a way that intersects these main fractures orthogonally would be the most productive. While a main stress component is a primary theme, local geological stress controls can also be a component so, the optimal orientation of may change according to local measurements as derived by well logs and seismic data.

Currently in Weld county it is “rumored” that horizontal wells drilled from North to South are the most productive, but it has been said that in the Southern DJ basin, wells may also be productively drilled from East to West.

Based on the stress field present in Colorado, that does not seem an unreasonable hypothesis.

So those are the geological controls, what about land position and field rules?

• Currently Niobrara field spacing rules by the COGCC for horizontal wells are units of 640 acre or perhaps a 1280 acre spacing.

It has been suggested that lateral horizontal wells will be drilled on section corners on opposing diagonals and fracked to drain the reservoir. The wells drilled from opposing corners will most likely intersect. From a simple geometric point of view this makes sense, however this does not take into account local geological fractures that control the flow (which is of course the most important factor) when drilling a well and seems a bit simplistic.

This theoretical drill pattern also presumes that access conforms to field rules and acreage is available for a drill pad to set the well in these ideal positions.

A more realistic view of what a horizontal drilling pattern may look like is provided by the following patterns used to drill in the 640 and 1280 acre spacing Bakken Play which can be considered a sister play to the Niobrara. These diagrams are slightly modified from Kordziel, 2007 It is highly probable that new alignments have been developed since this time, and it is also likely that in the Niobrara these lateral orientations may change to capitalize on the Niobrara fracture patterns.

Regardless of what you may be told as a landowner, the Operating Oil Company will alone determine where and how the wells will be drilled based on local fracturing, available land positions that take into account access and regulations.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Bakken Play in North Dakota – Sister Play to the Niobrara

To conclude, and reaffirm this section, please review the well placing for and horizontal drilling and fracking patterns for the Bakken formation in North Dakota. This is how the local geological controls of natural fracturing have decided how wells are drilled in this oil play. The implications for what the well placement and lateral patterns will be in the Niobrara Shale are clear.