Drilling fluids are crucial to the oil and gas industry, and so is the removal of filter cake formed by them. Pertaining to this, new improvisations are being made to achieve better rheology along with some other favorable properties. One of these advancements is the use of microemulsions as drilling fluids or as cement pre-flush. Novel microemulsion flushing fluids have been constructed for the effective removal of mud cake. The use of drilling fluids also creates the inevitable problem of formation damage, wherein the drilling fluid penetrates the formation and causes a decrease in permeability. Microemulsions have been used effectively to combat such damage caused by drilling fluids.

Methods, Procedures, Process

The main aim while preparing a drilling fluid is to obtain optimum rheology. And this is where microemulsions helped. The chemical/physical properties and damage mechanism of the formation were analyzed using several experimental methods, including X-ray diffraction, scanning electron microscopy, core inhibition test, etc. To develop an environmentally friendly drilling fluid, the main microemulsion system was constructed using an aqueous phase (water-glycerol solution 1:1), an oil phase (pine vegetable oil), and varying nonionic surfactants (Tween 80, nonylphenol ethoxylates 100 and 150). Two types of clays (filtration control) were used in the formulation of fluids, Brasgel PA and Cloisite 20 A, in the presence of a viscosifier (xanthan gum), a weighting agent (baritone), a sealant (calcite), and dispersant (water). For the effective removal of mud cake, the microemulsions for the flushing fluid were prepared with vegetable castor oil, 2%wt KCl as an aqueous phase, and a nonionic surfactant (Ultranex NP40). Various tests were performed to evaluate the performance of the flushing fluid formed.

Results, Observations, Conclusions

The use of microemulsion systems has led researchers to develop economical, environment-friendly, thermally stable, non-toxic drilling fluid or cement pre-flush that has low solid content, and low fluid loss. Microemulsions-based drilling fluids have also been used successfully to combat the problem formation damage in the Sulige gas field, in China.

Novel/Additive Information

This paper will review the numerous ways in which microemulsion systems are being incorporated into the oil and gas industry, particularly in drilling. It can help a drilling engineer come up with the Most Unexceptional way to prepare a microemulsion suitable for his needs, after going through the various methods and the properties achieved by them.

You can access this article if you purchase or spend a download.