Is high-density drilling fluid potassium formate useful for the stability of surrounding rock?

During the drilling operation, the drilling fluid keeps circulating in the well. If the density of drilling fluid is not properly controlled, accidents such as well collapse, leakage, or blowout may occur. Therefore, the density of the potassium formate drilling fluid also plays an important role in the stability of the surrounding rock of the shaft wall.

With the continuous development of drilling technology, there are more and more types of drilling fluids. At present, there are various classification methods for drilling fluids at home and abroad, among which the more concise classification methods are as follows:

1. According to the density, the drilling fluid can be divided into high-density drilling fluid and low-density drilling fluid.

2. Drilling fluid can be divided into inhibitory drilling fluid and non-inhibiting drilling fluid according to the degree of hydration with clay. According to the nature of the continuous phase, the drilling fluid can be divided into water-based drilling fluid, oil-based drilling fluid and gas-based drilling fluid.

Potassium formate was originally used early in drilling fluids abroad, especially in high-density drilling fluid systems. There are many low-density drilling fluids used in ordinary drilling, but potassium formate is a solid-free drilling fluid system, which plays an important role in the stability control of the borehole wall. The density of the drilling fluid is also the only controllable factor among many complex factors. Wetting the weighting agent with a small amount of water during the drilling process, and adding an appropriate amount of glue when weighting, can keep the high density potassium formate system low viscosity and low water loss.

Compared with the conventional inorganic brine drilling fluid, potassium formate drilling fluid has adjustable density (1.00~2.30g/cm³). It has little damage to formation, low solid phase content, thin and tough mud cake, can be acidified, and has good hole cleaning ability. It has strong inhibition, low corrosion, little environmental pollution, and can increase the high temperature stability of the polymer.

Compared with conventional polymer drilling fluids, potassium formate drilling fluid is distinguished by the fact that it does not use bentonite slurry, which fundamentally overcomes the drilling fluid to maintain the finely dispersed colloidal nature of the system bentonite and the stability of mud shale formation, inhibiting the cuttings in The contradiction manifested by the dispersion in the drilling fluid.