The following table presents the main drilling fluid functions and properties. FUNCTION RELEVANT PROPERTY OF MUD AND RIG SYSTEM EFFECT OF PROPERTY ON PENETRATION RATE AND BOREHOLE EFFECTIVE CONTROL 1) Removal of drilled cuttings from the hole a) Annular Velocity a) If excessive may create washouts in unconsolidated formations. a) … Drilling Fluid Functions and Properties
To optimize hydraulics and achieve sufficent hole cleaning the following guidelines should be adhered to: Pressure Losses Through System P1= Frictional losses in surface lines P2= Frictional losses in Drillpipe P3= Frictional losses in Drill collars PB= Pressure loss across bit P4= Annular pressure loss across Drill collars P5= Annular pressure loss across Drillpipe Surface … Hydraulics Optimization – Hole Cleaning
If conventional LCM pills prove ineffective, a gunk squeeze may be attempted. The method utilises the swelling property of Bentonite in the presence of water. This method is not to be used for losses in reservoir section. Allow four hours for the plug to set. The Bentonite will hydrate after the base oil is squeezed … Drilling Fluids Loses – Gunk Squeeze
If lost circulation is expected, the following recommendations should be followed: Nozzles of minimum 18/32in shall be used. As a rule-of-thumb, bit nozzles must be three times larger than the largest particle size of LCM, in order to reduce the possibility of blocking. If smaller nozzles are necessary a circulating sub shall be incorporated into … Drilling Fluids losses – LCM in Non Reservoir Section
If losses occur in reservoir sections, the following options are available: As a first step, the mud gradient shall be reduced, formation pressures permitting. If the gradient reduction provides no benefit, then use CaCo3 LCM material as follows: Formulation and Mixing Procedure for LCM Pills Calcium Carbonate shall be applied according to the details in … Drilling Fluids Losses: LCM in Reservoir Section
Flowlines, shaker header boxes (possum bellies) etc., shall be inspected regularly and cleaned out as required, in order to prevent solids build-up. Ditch magnet to be inspected as required if installed. Jet lines, if fitted, shall also be inspected regularly to ensure that they function properly. Settling tanks shall never be by-passed. Settling tanks shall … Solids Control Equipment – Flowlines and Settling Tanks
The importance of shale shakers as the primary solids control equipment capable of handling the full returns from the wellbore cannot be over stressed. They must be operated as efficiently as possible, at all times, in order to maximise the amount of solids removed at the first pass. Solids passing through the shakers will be … Solids Control Equipment – Shale Shakers
Design and operating principles can be found in suppliers literature. Mud cleaners consist of a desilter mounted over a fine mesh screen of 150‑240 mesh. The desilter underflow is treated mechanically by the fine 150-240 mesh screen which allows the liquid phase and any barites present to pass back into the circulating tank while the … Solids Control Equipment – Mud Cleaners
The following tests shall be carried out by the Mud Engineer to guard against possible wrong delivery of bulk material from supply vessels/trucks: – water/acid test– weighing method test The Mud Engineer shall ensure that the type of material is checked before the new delivery is loaded into the rig bins. Sampling on Arrival A … Drilling fluids QA/QC – Quality Control of Bulk Materials at Rig Site
The following tests shall be carried out, or fully supervised, by the Mud Engineer, to determine the quality of barites delivered to the rig. Sampling Barites shall be sampled using the same method as outlined for cement above. Testing Contamination of barites by bentonite is determined simply by the fact that severe gellation will occur … Drilling fluids QA/QC – Quality Control of Barites