Drilling muds are oil- or water-based suspensions that are used in drilling oil and natural gas wells. The muds have several critical roles in the extraction process. Some of the functions include:
- Lubricating and cooling the drilling bit. This increases the penetration rate during drilling and enhances equipment performance. Cooling and lubrication are the primary functions of drilling fluids.
- Providing the hydrostatic pressure that prevents oil and gas from escaping during drilling. Furthermore, the hydrostatic pressure prevents the entry of formation fluids into the wellbore.
- Removing rock cuttings from the well and preventing debris dispersion. This clears the well.
- Stabilizing the well during drilling thus minimizing damage to the production walls. Further, the drilling fluids prevent corrosion of the formation.
Drilling muds composition
Drilling fluids are tuned to have unique properties that suit their applications. For example, the drilling mud used in deep shelf drilling will have different properties from the mud used in drilling shallow wells. The desired properties are attained by adding different chemicals to the drilling mud. Typically, drilling muds contain the following additives:
- A bridging chemical to stimulate the formation of a filter cake in the well
- A chemical that controls the weight and density of the drilling mud
- A thickening and wetting additive. Such additives control the rheology of the mud
- Salts for stabilizing the well
Why is the particle size of drilling muds important?
The particle size is one of the most significant properties when evaluating the performance of the drilling mud. The particle size of the drilling fluid determines the equipment performance in a specific well. Below are some of the factors that make the particle size an important property of the drilling mud.
- When the particle size of the mud is smaller than the pores of the surrounding rock, the particle bridges the pores of the rock leading to the formation of a filter cake. The filter cake prevents fluids from escaping during drilling.
- If the optimum particle size is not correctly determined, tiny particles can penetrate the surrounding rock and block the rock pores, damaging the production zone.
- If the optimum particle size is accurately determined, the well will stabilize, and there will be minimal fluid invasion.
Particle size and preventing damage of the production zone
A thorough particle size analysis is particularly valuable in minimizing damage to the surrounding rock formation. Fine particles from the rock cuttings and polymeric material from the drilling fluids can damage the production zone. For the filter cake to be an effective barrier against the destructive agents, the particle size and particle distribution of the filter cake must be taken into consideration.
Aerion can assist with particle size analysis to evaluate the particle characteristics of different drilling fluids. Our highly-trained staff analyze the properties of the production zone to determine the optimum drilling fluid particle size for extraction efficiency and for protection of the production zone. To learn more about how we can help to prevent equipment issues and maximize performance, contact us here.