Taking Shale Gas Knowledge Global
The next major challenge that shale gas producers face in driving production efficiency is understanding and managing heterogeneity—both vertical, and lateral—according to Chris Hopkins, Schlumberger vice president, Unconventional Gas. This is becoming increasingly as important to global producers as it is to US producers.
Speaking as part of a panel discussing technology and innovations to encompass the unique properties of shale reservoirs at the recent Developing Unconventional Gas 2010 conference in Fort Worth, Texas, Hopkins stressed the need for the industry to use the lessons of the past to drive efficiency in the future.
Drilling in US shale plays
He outlined the history of some of the more developed shale basins such as the Barnett where there was relatively little change in the way wells were drilled from the 1980s to the 1990s. While multistage completions and water fracs were used more and more during this time to increase production, no dramatic changes were realized in the unconventional gas industry until the explosion in the volume of horizontal drilling around 2003. High drilling volumes meant that costs per well could be reduced through lean techniques, pad drilling, and other efficiency gains. During this period, well costs dropped from 7.5 million to 4 million USD.
From a technology efficiency viewpoint, average gas prices exceeding 6 USD in the early 2000s drove technology development and helped make horizontal drilling part of the industry’s current standard production-enhancing procedure. However, while efficient practices may have standardized well construction to some extent, production from these wells is far from standard. The variations in production result from the vertical variability among different shales. For this reason, Hopkins stressed the need to incorporate geomechanics to assist well designers to decide the best location to kick off horizontal wells and to best place them within the producing zone.
Considering vertical and lateral formation variations
“While many understand that vertical formation variations can significantly affect the overall production of a well,” Hopkins said, “another variation in the formation—that of lateral variability—can also impact ultimate production success and is far less well understood by most in the industry.”
Hopkins showed an example of the massive differences in contribution from perforation clusters along horizontal wellbores in the same shale formation. With more detailed knowledge of the lateral heterogeneity, decisions about where and when to land the well could be made with more confidence. In addition, well placement and completions would not only be more efficient, but with facies contacts located, also more productive. The resulting stimulation treatments, he said, would provide the best chance for every perforated cluster to produce gas.
To highlight how knowledge gained in the US in the last few decades could be used to help guide the increasing interest in shale gas around the world, Hopkins demonstrated the potential in one key area in Europe. He compared the Barnett Shale’s approximately 13,000 km2 of 11,000 producing wells with the massive potential of the Baltic Shale in Poland that extends over 100,000 km2 but currently has only five wells.
Using US experience in new fields worldwide
Hopkins said he believes lessons learned from the US shales could help drive efficiencies during the massive exploration phase currently underway in such plays worldwide. He added that the experience and expertise gained in the US fields could be used to help apply the technologies that will improve the economics and production of these newer fields.
“Integrating seismic with a range of subsurface measurements will lead to more accurate models that incorporate both vertical and lateral heterogeneities. This information can then be used to develop optimal development and completions plans specifically for each field. The results will assist the industry to not only improve production, but also to effectively manage water resources and operating footprint, while optimizing surface infrastructure requirements.”
Schlumberger: "Taking Shale Gas Knowledge Global"