Boosting US tight oil recovery rates

A new study indicates there is significant upside potential for US oil and gas operators to apply lower-cost unconventional drilling and completion technologies to boost production from tight conventional reservoirs, according to analysis from IHS Markita.

The study, Horizontal drilling in US tight conventional plays, is based on the assessment of nearly 46,000 US horizontal wells completed between 2010 and 2015. It studies how unconventional drilling and completion technologies could be applied to the redevelopment of conventional wells in the top 39 established US tight conventional plays where the major shale plays are also being developed.

The key plays identified in the IHS Markit study that have potential to leverage the horizontal technologies include the Rocky Mountain region (Williston, Powder River and Denver basins), the Permian Basin and Eagle Ford play fairways in Texas, and the mid-continent region, including the Anadarko Basin.

According to the market analyst, the average global recovery factor for a conventional oil reservoir is 34%, with two-thirds of the oil still left behind in the ground. Many tight conventional oil reservoirs, however, demonstrate recovery factors of only 15% or less, which is substantially lower than the average recovery factor for conventional reservoirs. (IHS Markit defines tight conventional reservoirs as those with permeabilities of 0.01 to 2.0 millidarcies (md) range that have tended to be sub-commercial in the conventional domain in the past.)

‘Our research indicates that there are significant potential benefits of applying some of the same drilling and completion techniques that have been used so successfully in the US shale oil plays to increase recovery in these tight, US conventional plays,’ says Steve Trammel, Director of North America well and production content at IHS Markit Energy. ‘We identified tight conventional plays that were tested with horizontal wells during the last five years, and in our study, which analysed nearly 46,000 US horizontal wells completed between 2010 and 2015, average initial potential (IP) test rates for the leading tight conventional plays compare favourably with the IPs of established shale oil plays. However, of the horizontal wells we analysed, just 10% of the horizontal wells drilled were in tight US conventional plays, so there is considerable potential here for operators.’ 

Lower costs
In addition, Trammel says leveraging these technologies is attractive to operators because the overall break-even costs to develop these projects are much lower and delivery infrastructure is already in place. ‘These tight conventional resources are in reservoirs with older vertical wells that can be re-entered by horizontal drilling. The rock properties do not require the size and cost of a hydraulic frack job needed for an unconventional zone, and therefore these are much more economic for operators in the current low oil price environment,’ he notes.

Additionally, Trammel says leveraging horizontal wells to further test tight conventional plays in these areas has led to the establishment of stacked plays with huge resource potential. ‘The plays in the Rocky Mountain region, in particular, have the majority of the highest-ranking tight conventional plays of those we studied in our IHS Markit Energy report, but tight conventional plays in Texas, including the Permian Basin and Eagle Ford fairway, also fared well in terms of potential for redevelopment.’

The IHS Markit Energy report includes an unexpected bonus for operators, according to Trammel. ‘Our analysis identified 25 tight conventional “sleeper”plays that have been tested with only a few horizontal wells, but have average IP rates greater than 200 boe/d. In addition, shallow conventional plays may also offer opportunities for operators to leverage these unconventional technologies in the current oil price environment.’