Shale Gas: What Challenges, What Future
The website Science.gouv.fr of the French Ministry of Higher Education and Research, features an interview with Roland Vially, a geologist at IFP New Energy.
In the article Shale gas: What challenges, What future?, Mr. Vially explains the some of the basics of shale gas.
The article below (translated from French courtesy of Google) provides a good overview for those not familiar with shale gas.
Shale gas: What challenges, What future?
Shale gas has experienced an extraordinary boom in recent years in the United States. In Europe, oil companies are only beginning to be interested in these unconventional gas resources which may be significant.
Shale gas is part of a group called unconventional gas because they can not be extracted with conventional production methods. They are now produced in large quantities in the U.S. where they account for 12% of gas production, compared to only 1% in 2000. Apart from a few countries that have no sedimentary basins, can be found shale gas almost everywhere.
In Europe, the consortium GASH, which in IFP New Energy participates, aims to spend the next three years mapping European resources. World reserves amount to more than four times the resources of conventional gas. If we came to use them, it would change the geopolitics of gas.
Question: Why has the production of shale gas developed so well in the U.S.?
RV: That is partly due to improved extraction techniques in recent years, particularly horizontal drilling and hydraulic fracturing of rocks that can increase the permeability near the well. The shale gas being dispersed in the impermeable rock, it is necessary to drill numerous wells and fracture the rock. Generally the depth of exploitation of shale gas is around 1,500 to 3,000 meters deep, from one to several kilometers below drinking water aquifers.
The well produces for several years and then is abandoned and a new well is drilled a few hundred yards away. The fracturing of the rock also assumes the injection of 10,000 to 15.000 m3 of water and sand at high pressures.
The low cost of drilling, access to private property and extensive private land rights, less stringent environmental regulations and tax incentives, coupled with technological advances, have contributed to popularity of the process in the US.
Q: Do these extraction techniques not pose any environmental problems?
RV: The environmental impact is not neutral even if it takes the perspective by comparing it with other industrial activities. The first impact is on water resources management, which includes three major aspects:
The availability of water needed for drilling and fracturing
Data is highly variable from one sedimentary basin to another and even within the same basin. However, the magnitude of the quantity of water required to achieve a drilling and hydraulic fracturing varies from 10,000 to 15,000 m3 as described above. For comparison, the water consumption of a city like Paris is an average of 550,000 m3 of potable water per day.
Recycling and water treatment fracturing
Part of the water that was injected to achieve hydraulic fracturing is recovered (20-70%) at the start of production from wells. This water can be processed on site at the drilling or be piped to a treatment center. Moving under high pressure in the sedimentary layers, it is usually loaded with salt and contains many elements in suspension. The water treatment removes chlorides, suspended material and metals, sulphates and carbonates in order to re-inject it in the following hydraulic fracturing. Note that this treatment (sedimentation, flocculation, electrocoagulation) is cheaper than buying, delivering and storing the same amount of "pure" water.
The fluid injected during hydraulic fracturing is formed by a mixture of sand and water with chemical additives (1% maximum). This mixture is injected under high pressure (over 100 bars) which will allow the artificial fracturing of the rock. The sand injected aims to keep the fractures open after the hydraulic fracturing performed to form a permanent drain through which the gas will be produced.
Chemical additives enhance the effectiveness of hydraulic fracturing and their composition may vary according to geological conditions. They can be classified into 3 major categories: biocides that reduce bacterial growth in the fluid but also in the well; products that promote the penetration of sand into the fractures; products that enhance well productivity. These products are commonly used highly diluted in everyday life, especially in detergents, cosmetics or disinfectants. At the request of consumer groups and U.S. authorities, many operators have published a list of products in the fracturing fluid.
Preventing possible contamination of drinking water aquifers by the drilling fluids
The rapid development of the exploitation of shale gas in the United States in recent years has led to some alleged cases of groundwater contamination by surface fracturing fluids. It seems that these cases are attributable to a lack of cementation in the upper parts of drill and not directly to the exploitation of shale gas or hydraulic fracturing.
Progress in monitoring and controlling the hydraulic fracturing of gas-rich layers of shale - which is usually located in more than a kilometer below the ground water - makes the risk of a direct connection between the shale layer exploited and groundwater very unlikely. To learn more about U.S. regulations and studies in progress, you can visit the U.S. Agency for Environment Protection.
Q: Is the footprint of operating facilities not a liability?
RV: In the case of shale gas, the geological layers involved are very porous and operators must drill many wells (more wells per km2).
These facilities, like any industrial facility, have a footprint. We must distinguish two phases in the exploitation of shale gas:
During the drilling and setting of production wells (a few weeks), the activity around the borehole is very intense and requires the presence of a derrick and a heavy logistics.
Once the wells are active, the natural pressure of the gas removes the requirement for pumps. On the surface, there is only a wellhead and a pipeline to evacuate the gas. To minimize the footprint but also to optimize the architecture, cost and the productivity of horizontal wells, the rigs positioned as a "cluster".
From a single drilling platform, 10 to 15 horizontal wells can be drilled. Therefore, the footprint of facilities may be reduced, making the rehabilitation of mining sites easier and less expensive.
The rational management of water resources (collection, treatment and recycling) and the refurbishment of operating facilities are not a technological obstacle or a hindrance to future developments of new projects. The rational management of water and of the landscape is essential: it is the guarantor of a sustainable, acceptable, shale gas.
Q: So what is future for Shale Gas in Europe?
RV: The exploration of gas shale has only recently begun in Europe but a there is considerable interest from E&P companies. The most interesting basins are located in northern Europe and east and south, particularly in France in the south basin. Total SA has been awarded an exploration permit in the region of Montelimar. Permits have also been issued in Sweden to Shell, to ExxonMobil in Germany, to almost all the of majors Poland and in Lithuania.
Given the environmental constraints but also an services industry less developed than the United States, operators must expect higher production costs in Europe than in the United States. The economic production of shale gas in a sustainable development framework and in line with the population, remains to be demonstrated. In all cases, their development will take time and is still in its infancy.
FP New Energy is a public research, innovation and industrial training, whose mission is to develop efficient technologies, economic, clean and sustainable in the fields of energy, transport and environment. It is funded by both the state budget and from own resources, from private French and foreign partners.
Source: Sciences.gouv.fr