Horizontal Wells in Tight Gas Sands—A Methodology for Risk Management To Maximize Success

摘要

In general, successful applications of horizontal wells have been limited to high permeability reservoirs and unconventional formations such as coal, chalk, and shale. Conversely, few tight gas sandstone reservoirs that require stimulation have realized sustained success with horizontal completions. One example of such success is the Cleveland Sand of North Texas and Oklahoma Panhandle region. Very recently, some success with horizontals has been observed in the Bossier and Cotton Valley Sands of East Texas and North Louisiana. Horizontal wells are commonly two to four times more expensive to drill and complete than offset vertical wells, yet are theoretically capable of up to three to five times the production. Higher gas prices have lead to potentially better economics for horizontal wells. However, research shows that in practice, many of these wells typically produce only 10 to 30% more than offset vertical wells. With costs more than double those of vertical wells, the economics are obviously unfavorable.