Modeling Source Rock Fracturing
The prerequisite to improving production techniques is being able to develop images of the rock behavior during and after fracturing. Total has already developed 2D tools to model fracture networks, but they cannot provide sufficient detail about rock response. To ensure the most realistic image possible, fracture propagation must be modeled in three dimensions.
Once developed, this new 3D tool will point the way to optimizing water volume and pressure levels, with the aim of enhancing fracking effectiveness. Better propagation of the cracks will not only boost the productivity of each well, but will also allow them to be sapcedd farther apart, resulting in decreased well density on production sites.
"Listening" as the Source Rock Is Fractured
Another way to study fracture propagation is to "listen" to the noises made by the rock. Total’s R&D teams have been working for several years on what is known as microseismic technology. This involves deploying ultrasensitive sensors able to record even minute tremors occurring 2,000 to 3,000 meters beneath the surface. Interpretation of the "noises" will yield an image of the fracture network, to further optimize fracturing techniques.
Water Conservation and Recycling
Curbing the considerable water requirements of the shale gas recovery process is another R&D priority. This effort consists of:
- Developing alternatives to hydraulic fracturing, aimed simultaneously at reducing water requirements and boosting the effectiveness of fracking.
- Innovating with new proppants (materials designed to keep the cracks open) designed to be both lighter and stronger than sand and requiring less water and additives for transport than sand.
- Developing technologies to enable the recycling of fracture flowback water. This is a major challenge. Today, the recycle rate varies according to the formation: it ranges from a mere 15 to 30% in the Barnett Shale to as high as 90% in the Marcellus Shale, both in the United States.
Total’s work in this area led us to deploy the world’s first ultrafiltration pilot for produced water, in 2010. Our researchers developed this technique, which enables produced water to be reinjected after treatment, thereby limiting the environmental footprint.
Ultrafiltration in Brief
Much more efficient than conventional techniques, ultrafiltration uses ceramic membranes to retain suspended particles - 8,000 times finer than a hair - and bacteria. No chemicals are required. It is a cost-effective alternative to conventional sand filters and disposable cartridges and delivers unmatched filtration quality.
A process widely used to treat surface water to produce potable water, ultrafiltration is now being explored by the oil industry. Our R&D teams are working to adapt this technique to deploy it on our various production sites.
Ceramic membranes are also used in the food industry, for example to filter milk or wine, and in the pharmaceutical industry, to concentrate active ingredients.