Schematic of typical horizontal well. Click image for full-size view.

“Getting gas from tight reservoirs”

 

Tight gas reservoirs are highly impermeable: pore spaces between grains in the rock is small and difficult to extract natural gas through conventional drilling methods. In order to economically extract gas from these reservoirs, technology needed to be developed to improve access. The solution appears to be horizontal drilling combined with hydraulic fracturing along the horizontal wellbore.

The growth in use of horizontal drilling technology and multi-stage fracturing has been tremendous over the last five years due to completion technology that can effectively place fractures in specific places in the wellbore. The technical objective of horizontal drilling is to expose significantly more reservoir rock to the well bore surface than can be achieved via drilling of a conventional vertical well. Economic benefits include increased productivity of the reservoir or prolongation of the reservoir’s commercial life.

 

As drilling technology continues to exploit these more complex and unconventional reservoirs, completion technology is being designed and developed to effectively fracture and stimulate multiple stages along a horizontal wellbore. By placing the fracture in specific places in the horizontal wellbore, there is a greater ability to increase the cumulative production in a shorter time frame. The objective of fracture stimulation of a reservoir is to increase well productivity by altering the flow pattern in the formation near the wellbore to provide an easier path for fluids to flow to the wellbore from the extremities of the well’s reservoir.

 

The use of horizontal drilling combined with the application of multiple-stage hydraulic fracturing techniques has increased the potential recovery of our Niton and Hooker plays. Compton’s average horizontal gas well is 2,600 meters deep and has a 1,000 meter open-hole section, and increases reserves by approximately 2 times that of a vertical well.  Multiple open-hole packers are set within the horizontal section and three to four staged hydraulic fractures are completed.