the biggest collection of oil well drilling books such as Drilling bits, Drilling Fluids, and Casing, links updated from time to time, all you have to do is to click on the icon under the required book name:
Casing Dimensions, Materials and Strength
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Drill Bit Technology
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Drilling Fluids Part.1
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Introduction to Directional Drilling
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Well head Components
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BOPE - Description and Selection
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Casing Heads
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Coordinates Systems
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Drill Bits Hydraulics Calculations
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Drilling Fluids
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Principles of Rheology
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SLP Well Coordinates and Directions
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Bit Hydraulics Optimization
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BOPE - Testing Procedures
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Survey Calculations
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Surveying Tools 1
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Surveying Tools 2
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Bottom hole Assemblies
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Down hole Motors
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Rotary Steerable Systems
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Cementing Flashs 
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MWD and LWD systems
Operation of Downhole Motor
Side Track Procedures
Shocks and Vibrations
Anti Collision
Well Design Fundamentals
Basic Maths of Well Planning
Manual Planning
Well Cementing Part.1
Well Cementing Part.2