One of the characteristics of drilling fluid is to improve the wall-building performance and promote the stability of the well wall. I believe this is well known. A well-performing drilling fluid can form a layer of filter cake with a lower permeability than the formation on the well wall. On the one hand, it can consolidate the well wall to prevent the wall from collapsing, and on the other hand, it can prevent the filtrate from entering the formation. Is potassium formate really drilling fluid?

API and IADC divide the drilling fluid system into nine categories, the first seven are water-based drilling fluids, the eighth are oil-based, and the last one is based on gas. 1. Non-dispersion system, 2. Dispersion system, 3. Calcium treatment system, 4. Polymer system, 5. Low solid phase system, 6. Saturated brine system, 7. Completion workover fluid system, 8. Oil-based drilling Liquid systems, 9, air, mist, foam and gas systems.

Compared with other drilling fluids, potassium formate drilling fluid has many advantages such as high temperature resistance, salt and calcium invasion resistance, well wall stability, good lubricity, and less damage to oil and gas layers. At present, potassium formate drilling fluid has become an important means for drilling difficult high-temperature deep wells, highly inclined directional wells, horizontal wells, and various complex formations. 

The mechanism of potassium formate has four main points: ion exchange, K ⁺ can replace Na in montmorillonite to form a stable structure that is not easy to swell and disperse; the crystal lattice is fixed, and the size of K ⁺ is just embedded in the oxygen atom grid between adjacent illite layers. Bonds are formed in the voids of the substrate, thereby limiting the expansion and separation of adjacent crystal layers; charge neutralization, high ion concentration in the potassium formate solution, can compress the electric double layer of clay colloid particles, and greatly reduce the negative electricity of the clay, and water Reduced swelling capacity; low activity, adding potassium formate will reduce free water in the drilling fluid and generate a certain osmotic pressure difference, which is conducive to preventing pressure from being transmitted to the shale, thereby inhibiting the expansion and dispersion of mud shale .

In general, it can be seen that the preparation and maintenance methods of potassium formate drilling fluid system are relatively simple, with superior performance and moderate cost, and are increasingly used by the drilling industry.