THE DRILLING MUD Following is a short section on the purposes of a drilling mud. These are briefly to: • Clean the bottom of the hole. • Cool the bit and lubricate the drill stem. • Transport the cuttings to the surface. • Support the walls of the hole; • Prevent entry of formation fluids into the well. • Transport the bottom hole conditions to the surface. • Transport the (MPT) Mud Pulses Telemetry to the surface. Other purposes of the drilling fluid are to permit the detection gas, oil or water that may enter the wellbore from a formation being drilled, and to transmit power to the bit. In addition, drilling fluid is sometimes used to drive a turbodrill or downhole motor that has been placed at the bottom of the drill stem. In this case, the drilling fluid provides power to the motor so that the bit turns without engaging the rotary table. - COMPOSITION AND NATURE OF DRILLING MUDS Water or oil are satisfactory drilling fluids in many instances. Generally, the functions to be performed require mud properties which can not be obtained from ordinary liquids. A typical mud consists of: (1) A continuous phase (liquid base) (2) Dispersed gel-forming phase such as colloidal solids and/or emulsified/liquids which furnish the desired viscosity, thixotropy and wall cake. (3) Other inert dispersed solids such as weighting materials, sand and cuttings. (4) Various chemicals necessary to control properties within desired limits. - TYPES OF MUD The most common types of the drilling mud are the following: 1- Fresh water mud 2- Calcium treated fresh water mud 3- Salt Saturated mud 4- Oil base mud
Posted on: Fri, 07 Nov 2014 20:56:02 +0000
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