Every now and then I get the opportunity to talk about the AAPG, and in particular the Division of Environmental Geosciences – but until now I have not had the opportunity to discuss the DEG with such a wide audience. And as I may never get this chance again, I am going to take this opportunity to tell you some things about the DEG and whom we are.
First let me explain where I am coming from and give you some examples of what many of the members in the DEG do.
I am a 35-plus-year AAPG member, but have been in the DEG for only about six years. When I first joined the DEG I didn’t really know much about the Division – and if you are not familiar with the DEG you may find yourself asking the same question I had: Just who are these DEG folks?
I have since come to embrace, respect and appreciate the diversity of the members of this division. As you will find, they are mostly a group of geoscientists who have many wide and varying interests, much like me. I like diversity in geosciences, and if you do too, and are looking for a fun place to come and unwind – you know, a place to get away from the 8-to-5 grind of sitting at the workstation, classroom or office – and if you are interested in learning some different styles of geological and geophysical exploration on the fringes of E&P, this is definitely the place for you.
The following are just a few examples of things that DEG members ponder:
Let’s say you are a geologist tasked with removing a slug of brine water from an aquifer. For the sake of an analogy for the petroleum geologists, let’s call the aquifer a reservoir and let’s call the slug of brine your target. Your target is located within an extremely heterogeneous clastic reservoir and horizontal wellbores, hydrofracing, etc., is not an option, so you can’t manipulate the reservoir and just drill wells anywhere you want.
Also you can’t depend on reservoir pressure to push your target to the wellbore, because your reservoir at this depth is at atmospheric pressure. So you have to drill wells and pump them at a certain rate, which is totally dependent upon the permeability and porosity of the reservoir rock within that wellbore.
You also have limited resources, so you need to place your wells where they will do the most good, don’t interfere with each other and have the exact radius of influence to recover your entire target.
Now, let’s complicate matters a little – because your target is brine, unlike oil, which is floating at the top of a nice trap with a seal; it is denser than the surrounding fresh water; and it is hugging the undulating, unconformable surface of the underlying, impermeable formation.
It also is confined to a paleochannel incised in bedrock and is moving at a rate of 2.5 feet a day in the down dip direction. You will need to drill numerous stratigraphic tests and core the reservoir to gather the needed porosity and permeability data and to also make structure and isopach maps, cross-sections, etc.
All of this then needs to be inputted into a sophisticated 3-D model.
OK, I think you are starting to get the picture.
If you are interested in learning more about hydrogeology, etc., we have DEG members who do this for a living all the time. We can arrange short courses, seminars, symposiums, etc. on the subject.
♦ Let’s say your expertise is mostly geophysical in nature. Using the same analogy above, you want to know the spatial and temporal relationships between the target and the reservoir, without going out and making a pincushion of the earth with wellbores.
There are numerous geophysical methods you can use, many of which are used every day in upstream oil and gas exploration such as seismic refraction and reflection to determine what the underlying bedrock structure looks like. You also can use geophysical methods such as electromagnetic surveys and resistivity profiles to determine the boundaries of the brine target. You can use typical downhole geophysical logging tools, such as induction and gamma ray in the wellbores to better define the vertical variations of the reservoir and target.
Want to learn things like this? We have an Environmental Geophysics Committee for you, staffed with world-renowned members who do this all the time.
This is just a sampling – there is not enough room in this article to even come close to describing all the other things we do in the DEG. If you want to find out more you just have to sign up.
I know you can find out more about these techniques joining other societies, but … hold on. Let me check … oh, yeah, for about $225 a year.
Or you can simply come join us in the DEG and let your imagination run wild.
Michael Jacobs is senior environmental specialist for Pioneer Natural Resources USA, Midland, Texas.
The Division of Environmental Geosciences (DEG), a division of AAPG, is concerned with increasing awareness of the environment and the petroleum industry and providing AAPG with a scientific voice in the public arena. Among its objectives are educating members about important environmental issues, supporting and encouraging research on the effects of exploration and production on the environment, and communicating scientific information to concerned governmental agencies.