Drilling Fluids: What Do Las Vegas and a Mud School Have in Common?
What do Las Vegas and a mud school have in common? What happens in Vegas stays in Vegas; what happens in a mud school can end up on the pages of National Driller. This month I thought I would take some common questions from the many different drilling disciplines we teach, and share them here. While some may not be from your industry, you still may get something from them. Based on the conversations after class, for every driller who raised his or her hand there are two or three more who wanted to.
Q: My state or province only requires me to grout the top 20 feet of the well. Why do you teach grouting the entire well bottom to top?
A: While there are many different standards that differ by state or province, my company has made the decision to teach best practices in our classes. Grouting and sealing the top 10 or top 20 feet is designed to protect from surface migration and ignores the serious issue of cross contamination from different aquifers at any depth along the bore path. By installing the grout through a tremie line and filling the annulus from the bottom to the top you have provided maximum protection to your customer and others sharing the water source.
Q: What is the difference between dishwashing detergent and a commercial drilling foam?
A: While technically dish soap and drilling foam are both surfactants, it is like comparing a Tums to an antibiotic. The bubble size of a basic soap is larger and weaker than the bubbles formed by a drilling foam. These small and tight bubbles can carry heavier cuttings to the surface. Think about the last time you purchased something electronic. There is a good chance it had bubble wrap around it with very small bubbles versus the wraps from the past with the big, loose air pockets. All industries evolve.
Q: Why am I having a problem with the bentonite settling out in my tank?
A: I can hear many readers out there answering this out loud as they read. The fact is, every drilling fluids class starts out by addressing this problem. It doesn’t matter where you take the class or what bentonite company is teaching the class, the answer is the same: Check your water. Yet mud engineers get on planes and drive to jobsites every week due to bentonite product complaints that, in the end, turn out to be water related. Even a water source you trust can change. Water from a city hydrant can change depending on what the water treatment plant was treating that day or what part of the city system you are on. Well water can change due to the season or water levels. The key is: Check your water first.
Q: Why do I have to use more than the mixing chart says to get the viscosity I am used to using?
A: This is very simple; viscosity is just one measure or characteristic of a drilling fluid. I can have two fluids that are a 45 viscosity and, if that is your only requirement for a good fluid, then drilling with the McDonald’s milk shake should work fine! All joking aside, you should rely on the manufacturer’s mixing guidelines for the product you are using.
Q: I’m sorry I dozed off, what were you saying?
A: While our discussion of plastic viscosity (PV) and yield point (YP) can be a little dry, there are take-home points you may want to know. One example is that PV correlates with your solid content. A high plastic viscosity means higher solids and should be avoided. That knowledge and more could change the way you drill. Some more advanced classes and basic construction drilling schools will go into depth on the proper use of a rheometer and the analysis of the readings. This is just one example of attending a class or taking a class.
Q: Why, when grouting, do I have a grout collar that floats out of the borehole?
A: Check your drilling fluid weight. When we grout, we displace the drilling fluid with the heavier grout. A good 20-percent solid grout weighs 9.4 lbs/gal. If you are using a drilling fluid that, for whatever reason, is heavier you will not be able to displace it with the grout. The solutions are either use a lighter drilling fluid mix or, if you must go heavy, thin out the fluid prior to grouting. If you must keep your drilling fluid heavy until grouted, you may consider switching to a geothermal grout and adding sand to weigh your grout. A warning about heavier drilling fluids: They have other disadvantages, like formation damage, a decreased rate of penetration and higher material cost.
Q: Todd, what can I do about really sticky clay? You’ve never seen clay like this!
A: Some drillers describe it as blue, green, red or {insert your color combination here}. Whatever color it is, rest assured it is not just in your area. Synthetic polymers can be very effective in inhibiting some clays from swelling, but there are times you will need to pull out the big guns. For problematic, sticky clays, I would suggest using the newer clay products on the market today. Unlike their synthetic counterparts, they actually disrupt the ionic charge of the clays, causing the clay platelets to break down. Unlike conventional thinners, these new-generation products have a minimal adverse effect on bentonite drilling fluid. For actual product names, consult your drilling fluid distributor or brand representative.
This is just a sampling of questions I have heard over the past year. I would recommend that if you don’t understand a point or a subject during a class, that you get with your favorite “mud expert” and get more information. I guarantee you will not be the first or the last person to ask any particular question. The most important thing is to keep taking classes and learning. If you’re learning, you’re growing and the opposite of that is … dying.
Q: My state or province only requires me to grout the top 20 feet of the well. Why do you teach grouting the entire well bottom to top?
A: While there are many different standards that differ by state or province, my company has made the decision to teach best practices in our classes. Grouting and sealing the top 10 or top 20 feet is designed to protect from surface migration and ignores the serious issue of cross contamination from different aquifers at any depth along the bore path. By installing the grout through a tremie line and filling the annulus from the bottom to the top you have provided maximum protection to your customer and others sharing the water source.
Q: What is the difference between dishwashing detergent and a commercial drilling foam?
A: While technically dish soap and drilling foam are both surfactants, it is like comparing a Tums to an antibiotic. The bubble size of a basic soap is larger and weaker than the bubbles formed by a drilling foam. These small and tight bubbles can carry heavier cuttings to the surface. Think about the last time you purchased something electronic. There is a good chance it had bubble wrap around it with very small bubbles versus the wraps from the past with the big, loose air pockets. All industries evolve.
Q: Why am I having a problem with the bentonite settling out in my tank?
A: I can hear many readers out there answering this out loud as they read. The fact is, every drilling fluids class starts out by addressing this problem. It doesn’t matter where you take the class or what bentonite company is teaching the class, the answer is the same: Check your water. Yet mud engineers get on planes and drive to jobsites every week due to bentonite product complaints that, in the end, turn out to be water related. Even a water source you trust can change. Water from a city hydrant can change depending on what the water treatment plant was treating that day or what part of the city system you are on. Well water can change due to the season or water levels. The key is: Check your water first.
Q: Why do I have to use more than the mixing chart says to get the viscosity I am used to using?
A: This is very simple; viscosity is just one measure or characteristic of a drilling fluid. I can have two fluids that are a 45 viscosity and, if that is your only requirement for a good fluid, then drilling with the McDonald’s milk shake should work fine! All joking aside, you should rely on the manufacturer’s mixing guidelines for the product you are using.
Q: I’m sorry I dozed off, what were you saying?
A: While our discussion of plastic viscosity (PV) and yield point (YP) can be a little dry, there are take-home points you may want to know. One example is that PV correlates with your solid content. A high plastic viscosity means higher solids and should be avoided. That knowledge and more could change the way you drill. Some more advanced classes and basic construction drilling schools will go into depth on the proper use of a rheometer and the analysis of the readings. This is just one example of attending a class or taking a class.
Q: Why, when grouting, do I have a grout collar that floats out of the borehole?
A: Check your drilling fluid weight. When we grout, we displace the drilling fluid with the heavier grout. A good 20-percent solid grout weighs 9.4 lbs/gal. If you are using a drilling fluid that, for whatever reason, is heavier you will not be able to displace it with the grout. The solutions are either use a lighter drilling fluid mix or, if you must go heavy, thin out the fluid prior to grouting. If you must keep your drilling fluid heavy until grouted, you may consider switching to a geothermal grout and adding sand to weigh your grout. A warning about heavier drilling fluids: They have other disadvantages, like formation damage, a decreased rate of penetration and higher material cost.
Q: Todd, what can I do about really sticky clay? You’ve never seen clay like this!
A: Some drillers describe it as blue, green, red or {insert your color combination here}. Whatever color it is, rest assured it is not just in your area. Synthetic polymers can be very effective in inhibiting some clays from swelling, but there are times you will need to pull out the big guns. For problematic, sticky clays, I would suggest using the newer clay products on the market today. Unlike their synthetic counterparts, they actually disrupt the ionic charge of the clays, causing the clay platelets to break down. Unlike conventional thinners, these new-generation products have a minimal adverse effect on bentonite drilling fluid. For actual product names, consult your drilling fluid distributor or brand representative.
This is just a sampling of questions I have heard over the past year. I would recommend that if you don’t understand a point or a subject during a class, that you get with your favorite “mud expert” and get more information. I guarantee you will not be the first or the last person to ask any particular question. The most important thing is to keep taking classes and learning. If you’re learning, you’re growing and the opposite of that is … dying.
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