Types of Water Based Muds

Types of Water Based Muds1, Clear Water.

Fresh water and saturated brine can be used to drill hard, compacted and near normally pressured formations.

Types of Water Based Muds2, Native Mud.

This mud is made by pumping water down the hole during drilling and letting it to react with formations containing clays or shale.

The water dissolves clay and returns as mud.

This mud is characterized by its high solid contents and high filter loss resulting in thick filter cake.

Types of Water Based Muds3, Calcium Muds.

The swelling and hydration of clays and shales can be greatly reduced.

Calcium muds are superior to fresh water muds when drilling massive section of gypsum and anhydrite.

The swelling of clay is reduced by 50% when the calcium concentration in water is 150ppm.

Types of Water Based MudsCalcium muds are classified as .

1, Lime Muds (containing up to 120 ppm soluble calcium).

2, Gyp Muds (containing up to 1200 ppm of soluble calcium with greater temperature stability)

Types of Water Based Muds4,Lignosulphonate Muds.(300F)

This mud type consists of fresh water, chrome or ferrochrome lignosulphonate, caustic soda, carboxyl methyl cellulose, or stabilized starch.

This mud is suitable when,

1, high densities of muds are required( 14lb/gal).2, High temperature stability about 250F to 300F.3, High tolerance for contamination by drilled solids, common salt, anhydrite, gypsum and cement is required.4, low filter loss is required.

Types of Water Based Muds5, Kcl/ Polymer Mud.(250F)

Kcl/ Polymer muds are provided with,

1, High shear thinning behavior facilitating solid removal through the shale shaker, desanders and desilter.

2, high true yield strength

3, Improved borehole stability

4, good bit hydraulics and reduced circulating pressure losses.

Types of Water Based Muds6, Salt Saturated Mud.

Salt saturated mud is one in which the water phase is saturated with sodium chloride.

This mud is suitable for drilling salt domes and salt sections due to its ability to prevent the hole enlargement.

When used with polymer, salt saturated mud can be used to inhibit the swelling of shale.

In reservoir section normally salt saturated muds are used to prevent formation damage as barite can do.