The Pros And Cons Of Drilling

867 Words4 Pages
As the Drilling troubles are very expensive and costly which the time lost is involved too, therefore the excellent schematization/planning required, the effective way to achieve this aim is to design drilling programs on the basis of expectation of all possible troubles rather than on precaution and self-control, it means that, the designers to Scrutinize and troubleshooting of the most prevalent drilling troubles, to solve the problems Beforehand. The list of above mentioned most prevalent drilling troubles as follow: 1- Pipe Sticking 2- Lost Circulation 3- Hole Deviation 4- Pipe Failures 5- Borehole Instability 6- Mud Contamination 7- Formation of Damage 8- Cleaning of Hole required 9- Damage to the General and Personnel Equipments 1-Pipe Sticking consequences: a) Could not pull up the pipe b) Could not lower the pipe c) Could not rotate the pipe Differential pressure A segment of the “drill string” is embedded in the “mud cake” on the sidewalls of the hole. It is held there by the differential pressure between the hole and the creation of mud cake. Necessary to apply the drag force to release the pipe, this is the remedy action of differential pressure, the magnitude of frictional force depends to the coefficient of friction and the entire magnitude of vertical pressure applied to area of the pipe on the sidewall of hole. The causes of differential sticking: - needless high differential pressures - Thick mud cake (gummy formation & high viscosity) - Poor lubrication of mud cake (excessive coefficient of friction) - Excessive embedded pipe length (sluggish movement during operation) How to reduce consequence of “differential sticking”: - appropriate mud specifications (weight, fluid loss) - Pro... ... middle of paper ... ... BHA, to fix stabiles or etc. 4-Drill Pipe Failures Common failures - Twist off - Parting - Burst or collapse - Fatigue - Leaking Nearly all of these failures are remedy by starting with an excellent string. Drill pipe and collars supposed to be continuously inspected and frequently tested according to planned maintenance program. 5-Borehole Instability Causes - in situ Mechanical stresses - ablation due to drilling fluids - Chemical contact of fluids and formations Problems - Hole shutting - Excessive in torque and drag force - Pipe sticking - Running and seating casing 6- Hole Enlargement - improper cementing - raise possibility of hole deviation - Hydraulic troubles in cleaning the hole - problem logging the well Fracturing - Lost circulation Collapse - Pipe sticking - Loss of the hole - 7-Producing Formation Damage
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