This month’s issue of National Driller focuses on rig maintenance and mud pumps. An important step in maintaining and protecting drilling tools and mud pumps is having a good mud program. This involves using the correct products for the drilling application and using these products in the way the manufacturer designed them to be used. This article will focus on products available for drilling and the correct way to use them.
An important step in maintaining and protecting drilling tools and mud pumps is having a good mud program. This involves using the correct products for the drilling application and using these products in the way the manufacturer designed them to be used.
Many of the drilling products used in the industry today have been around for a long time and are familiar to many contractors. It appears, though, from questions and calls we get as bentonite drilling fluid manufacturers, that sometimes some of these products and their applications are forgotten and a memory refresher is needed. There are also new products always appearing in the industry and those need to be noted as well.
This is true of basic bentonite drilling mud products. There are the “old stand-bys” that have been available for many years, but there are also new products that have been introduced more recently. Both the old and the new products have varying characteristics and varying applications. There are products that have:
- Higher barrel yields, such as 230-240 barrels per ton with low solids
- Standard barrel yields like 200 barrels per ton with low solids
- Lesser barrel yields in the neighborhood of 165-185 barrels per ton with slightly more solids
- Lower yields such as 90 barrels per ton and higher solids, which results in more bentonite platelets for more difficult drilling conditions
- Additional additives for hole stabilization, fluid loss control and increased carrying capacity (gel strength)
To select one of these products, one of the most important pieces of information needed by a drilling contractor is the kind of soils that will be encountered in the drilling project. Once this information is known, a drilling mud program can be formulated that includes bentonite drilling mud and possibly additives to enhance the bentonite.
Most of the time, a 200-barrel product will be adequate, but there are situations where a drilling contractor may need one of the higher yielding products or additives that control certain drilling problems that may arise. This may involve stabilizing the hole, lowering fluid loss to the formation, or problems with the fluid carrying larger cuttings. Some of the higher yielding products are referred to as “one-sack mixes” because they contain extra additives for tougher conditions.
Some major reasons for using drilling fluids are:
- To cool and lubricate the drilling tools and the borehole
- To suspend and carry drill cuttings
- To control fluid loss
- To control swelling clays and shales
- To stabilize the borehole and prevent cave-ins
- To control formation pressures
After the contractor knows which type of soils will be encountered, the proper mud can be selected along with any additives that may be required to successfully drill the well. Depending on conditions, the contractor may elect to use a 200 barrel bentonite and build his own special recipe using additives that are available rather than use the one-sack mix products.
There are also various types of additives that can be applied to various soil types. Again, there are some old stand-bys along with new products that have been added in recent years. There are additives that help to control clays:
- Long chain polymers (PHPAs), which enhance bentonite drilling mud by increasing viscosity and controlling swelling clays
- Short chain polymers that accomplish the same things as the long chains, except they do not raise viscosity
- Products that actually break clays down and liquefy them so they can be removed from the borehole
- Surfactants that make drilling mud wetter and minimize bit balling
There are additives that help control sands, gravels, and cobble:
- These are called PAC Polymers
- There are both dry and liquid versions of the PACS
- There are PACS that raise the viscosity of the drilling mud and another version that does not raise viscosity
- There are natural polymers that increase gel strength of the drilling mud for increased carrying capacity
There are additives for well development:
- Products that break down bentonite drilling mud or natural clays in the well
- Products that break down polymer additives
- Products to break down foam used in air drilling
A number of the additives listed above can be used with drilling foam in air drilling as well as in mud drilling. To find out more about all of the products discussed here, please contact the area distributors or the manufacturers who make them. There are also numerous classes offered in the industry that can be attended and there is product literature available from distributors and manufacturers. This literature is also available online. Manufacturer websites are an excellent source of product information, along with calculators to figure how much product is needed.
Once the right products have been selected and the project is ready to commence, there are two very important factors for success:
- The quality of the make-up water for mixing these products needs to be considered
- The equipment used to mix the make-up water and the bentonite or foam is very important to get the most yield out of the products used
Make-up water is one of the most important aspects of drilling mud. After all, it makes up a majority of the drilling fluid. Much of the water available from municipal and other sources has a pH lower than 7, which is neutral. Bentonites, foams and polymers work better in a pH range of 8.5 to 9.5. The pH can be raised by small additions of soda ash. Usually ¼ pound to ½ pound per 100 gallons of water will accomplish this change in pH.
Soda ash will also precipitate out calcium in hard water, which also improves the yield of bentonite, foam and polymers. Proper mixing equipment such as a venturi hopper is recommended for bentonite drilling mud and polymer additives. The platelets in the bentonite need to be separated in order to get maximum yield, and this can be done with a good, strong venturi. Good mixing is also important for foam and the additives used with foam in air drilling.
The two choices involve the cost and the speed at which the drilling spoils need to be solidified. The bentonite-based are the most economical, but they are also the slowest to solidify, while the polymer-based products are the most expensive, but also very fast acting.
When the drilling project is completed, there are some new products that can help with disposal of drilling fluids. These fluids can be solidified with these products so that they can be disposed of in a landfill or other disposal facilities or, if allowed, simply buried on the drill site. There are bentonite-based products, polymer-based products and products that combine both the bentonite and polymer. The two choices involve the cost and the speed at which the drilling spoils need to be solidified. The bentonite-based are the most economical, but they are also the slowest to solidify, while the polymer-based products are the most expensive, but also very fast acting.
If you have questions on the discussion above, please contact me through National Driller.