Volume Capacity and Displacement

Mud System Volume - The total mud system volume may be calculated with the drill string either in or out of the hole. Total Mud Volume Pit Volume Hole Volume 2. Pump Output Volume - Pump output tables must be adjusted for estimated or measured pump efficiencies. Triplex pumps usually have an efficiency between 90-98 . Double action duplex pumps usually have an efficiency between 85-95 . The following two equations calculate pump output at 100 volumetric efficiency. The constant, K, may be...

Carbonate Bicarbonate Contamination

The most common source of soluble carbonate accumulation in muds is CO2 intrusion from formations being drilled. As CO2 enters an alkaline mud, it reacts with OH- ions and soluble carbonates accumulate. Another common carbonate source is thermal degradation of organic additives such as lignite and lignosulfonate at temperatures in excess of 300 F. CO2 is liberated at temperature by alkaline decarboxylation of organic acid groups such as found in humic acid. Lignite is a more potent source of...

Advantages Disadvantages of Air Drilling Fluids

There are a number of significant advantages for using air as a drilling fluid. Table 5 lists some of these advantages as well as some of the disadvantages. Excellent ROP in dry competent formations. Dust and noise problems on location. Excessive erosion near top of hole where expansion results in high annular velocity. Minimum damage to water-sensitive pay zones. May cause downhole fire when hydrocarbons are encountered. Air Drilling Little or no fluids disposal problems. Hole cleaning success...

Retort Water Oil and Solids

Retort Mud

Accurate measurement of water, oil and solids content provides fundamental information for control of mud properties and is essential for evaluating solids control equipment.___ The volume percent of liquid phase water and oil are measured by heating a known volume of whole mud in a retort unit. The liquid is evaporated from the mud, vapor is condensed and measured as oil and fresh water in a graduated glass tube. Suspended solids are calculated by difference of liquid collected subtracted...

Anhydrite Gypsum Contamination

Anhydrite and gypsum are calcium sulfate compounds CaSO4 which are sometimes encountered while drilling. Gyp is calcium sulfate with water of crystallization CaSO4 2H2O , while anhydrite is the anhydrous waterless form of calcium sulfate CaSO4 . These may occur as thin stringers or massive beds. Calcium sulfate contamination is similar to cement contamination because both liberate calcium ions, which in turn cause flocculation. Unlike cement, calcium sulfate does not cause a pH increase since...

Zinc Carbonate Scavenger

There are several methods commonly used or available to determine the presence of H2S in drilling fluids. Gas detectors or monitors are used on drilling rigs to detect unreacted H2S gas at the surface. The Hach test is used to detect H2S in the acid form, or as soluble sulfides in the makeup water, filtrate or mud. The Garrett Gas Train also analyzes the soluble sulfides in the filtrate of the mud. In addition, both tests can also determine the total sulfides, both soluble and insoluble, in a...

Principal Additives of KCl Polymer Muds

KCl-Polymer Muds with low KCl concentrations typically 3-5 wt and low densities are easy to maintain when drilling harder formations. However, when increased densities are required, mud composition is more complicated and mud properties are more difficult to control. Materials and concentration ranges for KCL-Polymer Muds are listed in Table 32. Not listed is poly propylene glycol , or PPG, such as DCP-208, which is gaining increasing popularity as an inhibitor aid. This low-molecular weight...

Methylene Blue Capacity

Methylene Blue Test Drilling Fluid

The methylene blue capacity test indicates the concentration of reactive clays present in a drilling fluid. Reactive clays are commercial bentonite and formation solids such as shales. Methylene blue dye is added to a sample of whole mud until all reactive sites have adsorbed the dye. A faint blue turquoise halo will form around the drop of solids when there is an excess of dye. Drilling muds frequently contain other materials that adsorb methylene blue. Treatment with hydrogen peroxide is...

Designing Pilot Tests

Drilling Fluid Tests Lab

Adjustments to mud properties such as changing fluid loss properties treating carbonate bicarbonate contamination adjusting MBT - clay content of the mud changing oil water ratio of oil muds increasing electrical stability of oil muds 4. Study of effects of breakover, converting or displacement of muds, such as displacing water-based mud with oil-based mud or vice versa converting from freshwater mud to saturated salt mud breakover to lime or gyp mud reducing...