Water well and geothermal drilling play a vital role in meeting the world’s growing demand for clean water and sustainable energy. However, people often overlook one significant aspect of successful drilling operations: effective control of solids.
Solids control, of course, means the critical process of managing and removing unwanted particles from drilling fluids. It helps ensure the efficiency and longevity of the drilling equipment and the overall success of the operation. Effective solids control can range from the simple and traditional mud pan or pit, up to expensive mechanical equipment utilizing shakers, cones and even in critical operations centrifuges.
Most of us learned to drill utilizing a pit or pan. Given that, when newer technology becomes available that would make our job easier, safer and cleaner, you would think we would jump at the opportunity. By and large, however, drillers and drilling companies have been slow to embrace mechanical solids control. Why haven’t people adopted the use of solids-control equipment? The most common answers I hear include:
- I can’t afford to purchase solids-control equipment.
- I’ve tried using solids-control equipment in the past and it doesn’t work.
- I don’t need solids-control equipment. The way that we’ve always done it works just fine.
The real question is how can you afford to not use solids-control equipment? Utilizing solids-control equipment can:
- Make your job cleaner overall
- Reduce downhole problems
- Reduce development time for the wellbore
- Assist in installing casings and ground loops
- Reduce maintenance costs on your pumping equipment and downhole assemblies
The presence of drilled solids in drilling fluids can lead to various challenges. These solids, often composed of sand, silt, clay and other debris, can hinder penetration rate. It forces the bit to regrind the cuttings not properly removed by the settling pit. These reground solids interfere with the bit’s ability to connect with fresh new formation, thereby slowing production. As these reground solids get smaller and smaller, they become more entrained in our drilling fluid. Our mud weight rises as a result. Rising mud weights increase the effective pressure on the formation. At the same time, the increased solids cause the filter cake on the wellbore wall to thicken while also allowing more fluid to filtrate pass into the formation.
Think about the last time you lost circulation. Was it because the formation really was that porous, or did poor control of mud properties play a part? I often get calls from the field when someone has issues. Many times, one of the first questions I ask is what are your mud weight and viscosity? You should always monitor these — at a bare minimum — when it comes to your mud properties. Too often, when I ask this question, the driller either doesn’t know or doesn’t have the ability to do the test (or has not yet done the testing). You cannot fix a problem until it you identify it, and you cannot identify a problem without information. Initial and periodic testing gives a driller the information needed to make changes before problems occur.
Viscosity really measures how difficult it is to pump your mud, not your mud’s effectiveness in holding back a formation. Mud weight is a basic measurement of the density of the fluid. Water, for example, has a weight of 8.34 pounds per gallon. Throw in bentonite and other common additives with the exception of weighting agents, ) and our mud weight may climb to 8.5 to 8.7 pounds per gallon (depending on the amount of benonite, added to drill the required formation). Any density above that initial mud weight comes from drilled solids being entrained in our fluid. A further simple test for sand content and can also determine the abrasiveness of our drilling fluid.
Drilling with high-solids mud causes increased wear and tear on drilling equipment. Moreover, if not effectively controlled, solids can flow into the formation and be difficult or impossible to develop out. This impedes the flow of water into the well, reducing the well’s yield and overall productivity. Geothermal drilling faces similar challenges related to solids control. The presence of solids in geothermal drilling fluids can lead to operational downtime and difficulty in setting and grouting loops. In open-loop and Darcy-type installations the accumulation of solids in the geothermal wellbore can diminish heat transfer efficiency, reducing the overall effectiveness of the geothermal system. Effective solids control is, therefore, imperative to ensure the long-term viability and efficiency of geothermal systems as well as water well specific capacity.
This emphasizes the importance of robust solids-control measures to maintain the integrity of drilling system performance. Proactive solids control also minimizes the environmental impact by preventing the discharge of contaminated fluids into the surrounding soil and water sources. Ultimately, efficient solids control positively impacts the overall cost-effectiveness of drilling projects.
So, given all I’ve talked about, here are my answers to the most common answers drillers give when I ask why they have not yet adopted the use of solids-control equipment:
I can’t afford to purchase solids-control equipment.
Like many things in running a small business this is about return on investment. Renting a solids-control system over a short term can allow your business to become more efficient and increase the client’s perception of the overall professionality of your operation.
I’ve tried using solids-control equipment in the past and it doesn’t work.
Training! Training! Training! Attend a mud school in your area, preferably one making good use of a solids-control system as part of the training. Solids-control equipment often fails when the operator does not fully understand how one drilling fluids additive or another affects the ability of the solids-control equipment to work. Like everything else in drilling, the formation dictates how we approach any wellbore. If we stay inside the limitations of our equipment, that equipment should always increase the value of having it on the job.
I don’t need solids-control equipment. The way that we’ve always done it works just fine.
That’s awesome! Your company has no need to grow and regulations in your area have not (yet) forced you into a change. However, many jobs require mechanical solids control and high-profile jobs most definitely do.
That’s awesome! Your company has no need to grow and regulations in your area have not (yet) forced you into a change. However, many jobs require mechanical solids control and high-profile jobs most definitely do. If you do not read that and see a need for a change, I hope your competitors feel the same way you do.
In conclusion, the importance of effective solids control in groundwater and geothermal drilling cannot be overstated. It is a multifaceted process that not only safeguards drilling equipment and ensures the longevity of wells, but also contributes to environmental sustainability and cost-effectiveness. As the world continues to grapple with the challenges of water scarcity and the transition to sustainable energy sources, investing in solids-control technologies becomes paramount for the success of drilling operations and the broader goals of global resource management.Until next month, stay safe, keep your mud clean and keep turning to the right.