What are the functions of drilling mud additives

 　The composition of drilling waste mud is complex, mainly composed of clay, weighting materials, various chemical treatment agents, sewage, dirty oil, drilling cuttings.

　　During the drilling process in oil fields, drilling mud additives are prone to increase viscosity due to the need to penetrate the clay layer on the working surface. In this case, amide is needed to increase the density viscosity of the drilling fluid. The density viscosity of the drilling fluid should fully consider the slurry making performance drilling speed of the underground clay layer. During daily maintenance, the increase in density viscosity should be strictly controlled to avoid clay pollution. Sandstone generally has poor cementation, sand particles are prone to invade the drilling fluid, causing an increase in the density viscosity of the amide drilling fluid. It is required that the drilling fluid entering the well has a lower density, viscosity, appropriately high shear force. It is also required to use some drilling fluids with good anti collapse performance to prevent mud sand pollution collapse, to strictly control the sand content of the drilling fluid.

　　Due to severe mud making in the mudstone section, the use of tackifiers is either reduced eliminated. The usage amount is based on maintaining normal carrying of drilling cuttings. Viscosity is only a physical parameter in the rheological properties of drilling fluids. For drilling fluid, excessive viscosity makes it difficult to start the pump, slow drilling speed, poses significant safety hazards; If the viscosity is too low, it cannot effectively carry rock cuttings, leading to adverse consequences such as sticking the drill. Thickener can form a structure with clay to increase viscosity, while viscosity reducer is used to effectively prevent the hydration of clay to achieve viscosity reduction.

　　Due to different depths of cementing wells, it is required that the cement slurry has an appropriate thickening time to meet the needs of safe operations. Thickening time regulators include coagulants retarders. Accelerator is an additive that can quickly solidify cement, commonly used include calcium chloride, sodium chloride, etc; Retarders are additives that can prolong the setting thickening time of cement slurry. The commonly used retarders include lignosulfonate its compounds, hydroxycarboxylic acid salts (such as citric acid Tartaric acid) its compounds. When drilling into the target layer, in order to protect the oil gas reservoir, a special drilling fluid is often used for drilling, which is called completion fluid. Common completion fluid additives include Carboxymethyl cellulose, hydroxypropyl cellulose, polyacrylic acid, polyanionic cellulose, etc.