Water is an indispensable basic component for preparing various drilling fluids.

In water-based drilling fluids, water is the dispersion medium, and most treatment agents work by dissolving in water; in foam drilling fluids, water also serves as a continuous phase, and air is dispersed in the water under the action of foaming agents and foam stabilizers; in water-in-oil emulsion drilling fluids, water is the dispersed phase, and the water often contains a certain amount of inorganic salts, such as sodium chloride and calcium chloride. In the mist fluid, it acts as a dispersed phase and is dispersed in the air in the form of small particles.

Practice has proven that the performance of Drilling Aid is closely related to the properties of the slurry water. In most cases, in order to save costs, local materials are used. However, water quality varies greatly in different regions. Various impurities, inorganic salts, bacteria and gases in the water have a great impact on the performance of drilling fluids.

For example: inorganic salts: will reduce the pulping rate of bentonite and increase the filter loss of drilling fluid;

Bacteria: starch treatment agents ferment, polymer treatment agents are easily degraded, and the massive proliferation of bacteria will also cause damage to oil and gas layers;

The presence of gas will intensify the corrosion of drilling tools, etc. Carbon dioxide, cavitation, carbonic acid

Therefore, when preparing drilling fluid, the quality of the slurry water must be known in advance, and unqualified water must be properly treated before use.

Classification of water in nature

1. According to the source: surface water and groundwater;

2. According to its acidity and alkalinity: acidic water, neutral water and alkaline water;

3. According to the type of inorganic salts contained: NaCl type, CaCl2 type, MgCl2 type, Na2SO4 type and NaHCO3 type water, etc.

In the drilling fluid process, according to the content of soluble inorganic salts in the water, the slurry water is generally divided into the following three categories: Fresh water with less salt content (total salinity is less than 10 000mg/1), the drilling fluid is called freshwater drilling fluid

Salt water with more salt content, the corresponding drilling fluid is called brine drilling fluid

Saturated brine with a salt content of saturation, corresponding to the drilling fluid is saturated saltwater drilling fluid.

In addition, water containing more Ca2+ and Mg2+ is often called hard water.

Crude oil, diesel and low-toxic mineral oil are also commonly used raw materials when formulating drilling fluids. In oil-based drilling fluids, diesel and mineral oil are often used as the continuous phase. In water-based drilling fluids, a certain amount of crude oil or diesel is often mixed to improve its lubrication performance and reduce filter loss. During use, attention should be paid to the viscosity of the oil not being too high, otherwise the rheology of the drilling fluid will not be easy to control. In addition, the price of oil crystals and possible environmental impact should also be considered. For exploratory wells, the impact of fluorescence on oil and gas displays should be considered. When selecting crude oil, its freezing point and paraffin, asphaltene content, etc. should be considered to avoid adverse effects on the oil and gas reservoir.