Water Management Leader Sees Mexico as Innovation BaseWed, 10/21/2015 - 16:47
Q: As one of the leading suppliers of mine hydrogeological services, what value does Schlumberger bring to mining companies operating in Mexico?
A: We have been working with PEMEX since 1936, providing services for wireline, well field development, drilling, and construction. We now want to apply our oil and gas expertise in water resources management to the Mexican mining industry. We have already made significant advances in well design and pumping systems for dewatering large open-pit mines in Mexico. In doing so, we have differentiated ourselves from other service providers. For example, we have adapted our artificial lift systems, an extremely important component for handling fluids in hydrocarbon extraction, to mine water extraction.
Large open-pit dewatering wells require powerful highefficiency pumps to deliver water to the surface under high flow and dynamic head conditions. By using artificial lift systems, we are now able to drill smaller-diameter wells, where pumps can deliver higher flow and head capacity. This approach has revolutionized the dewatering programs for several of the mines that we have serviced. Reducing the diameter of wells used for bedrock dewatering, and thus pump size, has also decreased costs for our clients, who would otherwise have to drill larger-diameter boreholes to fit larger pumps. For example, instead of drilling a 22in borehole, we have reduced the size to 16in; and we can use 10in casings and screens rather than 12in. Consequently, the savings are significant, reaching a reduction in drilling costs of about 20%. Similarly, the pumps now used are more efficient in terms of their ability to sustain high flow rates at high dynamic head with each well typically pumping 30-60l per second from as deep as 700m, which is relatively deep for dewatering purposes.
Similarly, we have carried over our oil and gas directional drilling practices to open-pit mines, which previously were strictly vertically drilled. Directional drilling enables horizontal wells to be drilled under an open-pit mine, crossing through the water-bearing formations laterally at multiple locations. Horizontal drilling also enables the wellhead to be positioned outside the pit so that it can remain undisturbed by mining operations for years.
This results in more sustainable production and higher accumulative flow than can be achieved with in-pit wells. To date, we have drilled two directional wells, one in the US and one in Mexico with a third well in progress, and we believe that more companies will begin looking at this solution. These accomplishments are significant milestones and reflect the extent of Schlumberger’s mine hydrogeology and dewatering services in the Mexican and other mining markets. Another service we provide is our PetrelTM E&P software platform, a robust 3D geological modeling tool. Although mines have their own 3D models from various software platforms, Petrel allows users to input different types of information, including geology, lithology, and geologic structures. The Petrel software platform creates a clear picture that allows us to determine the best position for directional wells. We know that lithology, rock quality data, and mineral alteration have a big influence on the hydrogeology around open-pit mining. By using Petrel 3D images, we can design each well according to an optimal position and trajectory that allows dewatering as efficiently as possible.
Q: Subsurface geological modeling requires a certain level of optimization to guarantee accurate rendering. With this in mind, how do you go about carrying out your 3D modeling?
A: We collaborate with the geology departments of each mining company since they have their own data sets from exploration and geotechnical drilling. We add their data to our Petrel model to create a 3D image. We also use our own data obtained during the hydrogeological characterization of the mine. We do some conventional drilling and hydraulic testing to determine how much water a particular borehole will produce and its relationship to the desired well architecture. For example, we might convert it into a piezometer to monitor groundwater levels that will change as a result of our pumping activities. We typically want to see how we are affecting the drawdown of groundwater in the pit. Even though we are doing a lot of our own characterization, most of the data comes from the mine’s team. We also do groundwater flow modeling, usually with the US Geological Survey’s MODFLOW as a reference. MODFLOW, a 3D finite-difference groundwater model, is considered an international standard for simulating and predicting groundwater conditions and groundwater and surface-water interactions. This modeling gives us an idea of the required flow rate, or how many liters per second we need to pump in order to lower the groundwater levels enough to create dry conditions for mining. Some mines have a lot of water and others not as much, but all mines have problems at times with pore pressure. Even though there may not be much flow, a certain amount of water in the formation will affect the stability of the slopes. By drilling horizontal wells, we can drain the formation laterally to control the pore pressure so that the geotechnical engineers can maintain an optimal pit slope, an important factor that impacts the economics of the mine itself. Stability is an important issue. We dewater or depressurize so that companies can mitigate the possibility of slope failures. We do a lot of the consulting for mines on slope stability and work closely with their geotechnical engineering teams. We use geotechnical and hydrogeological data to create a pore pressure profile so that the teams can design a safe pit slope, another example of our modeling capabilities. Along with flow modeling, we conduct studies that focus on the regional impact of dewatering because our clients need to know how their actions will affect the permitting process.
Q: Which of Schlumberger’s services have still not been fully taken advantage of in the Mexican mining industry?
A: The work we are doing in Mexico has been truly innovative, to the point that some of our other offices are interested in applying these experiences elsewhere. In Mexico, we are setting standards for technology and innovation to be used around the world. Having already applied oil and gas technology twice to the mining industry, and now going into our third project, we are proving the commercial feasibility of this technology for the mining industry. We know that we can drill these wells in hard rock, complete them, and pump a target amount. Therefore, this technology has a lot of potential in any mine worldwide that has excess groundwater which needs to be managed.
Wireline geophysics, developed extensively by Schlumberger, can also be applied to mining in Mexico. While the use of advanced wireline geophysics is a relatively new approach to mining, companies are becoming more accustomed to it, which is to our advantage. Regarding heap leach operations, for example, we have used numerous new applications to prove that Schlumberger can make measurements that were not possible before. We can measure changes in the copper concentration in a heap, and we can collect samples of a pregnant solution from a heap with our proprietary WestbayTM multilevel groundwater characterization and monitoring system. In addition, we can use fiber optics and electrical resistivity with advanced wireline geophysics to do 3D imaging. By making measurements in near real time, an operator can optimize its leaching operation. This technology has great potential in Mexico.
The mining industry is advanced in terms of automation, such as in conveyor belts, excavating, and material movement, but it has moved more slowly than the oil and gas industry when it comes to geophysics, such as logging boreholes to determine technical properties. Schlumberger has pushed the envelope of numerous applications currently not used in mining but that if applied could improve processes. We hear people say, “we have been doing it for a long time, why should we start doing it differently?” So we try to push these technologies by proving their advantages in terms of economic value.
Q: Which role do you foresee geochemistry and other environmental sciences to play in your portfolio of environmental services?
A: When we offer mining hydrogeological services, we also offer our environmental services. Water resources and environmental services are strongly linked in terms of ground and surface water, and some of the models that we use for mining can be used to for environmental work. These services are important for obtaining permits and for post-closure modeling – for example, determining what the quality of pit lake water and groundwater will be at the end of a mine’s life cycle. We have experienced geochemists who work with acid rock drainage analyses for mines, especially important for pit closure models when pit lake chemistry must be evaluated. Our philosophy for geochemistry services is the same as for our other service lines in general: manage water to prevent problems while a mine is operating and not waiting until it closes, when the costs will be much higher. We are involved in geo-environmental characterization of mine materials and metal leaching studies as well as groundwater quality sampling and characterization.
Q: How interested do you feel the Mexican mining industry is in adopting innovative operational techniques and strategies?
A: Our work in Mexico is an indication that the mining industry is interested in making the step change to have a higher level of confidence in innovation, leading expertise, and collaborative teamwork. While our business is growing in Mexico, we are delivering a higher level of fit-for-purpose mine solutions focused on mine water management and subsurface characterization. The relationships we are building will help both our clients and Schlumberger advance operations and minimize uncertainty