Designing production safety systems

Acknowledgement viii Preface vii 1 What is safe? 1 Lossof controlon flowingwellsis rare, but the consequencescan be great. Safetysystemdesignis aimedat reducingthe chanceof failureand the loss when failure does occur. 2 History of safety valves 7 Great strides have been made in safety valve technology since the early 1930's whena demanddevelopedfora downholevalvethatwouldshutin the wellin case of wellheaddamage. 3 Regulations and standards 20 A varietyof governmentregulations,industrystandards,and recommended practices apply to the design of safety systems. Familiarity with these is a key to proper system application. 4 Symbols and definitions 29 Understandingthe symbolsused by variousorganizationsin describingthe concepts and equipmentinvolved in safety systems is necessarybefore proceedingto design. 5 Safety systems criteria 36 A basic safety system has several functions that are common to most applicationsI.n some cases, more than one function is combinedin one component, increasing complexity. 6 Lease equipment 42 Understanding lease equipment operation and its function is a key to applying the most appropriatesafety system technologyin productionoperations. 7 Valve types and application 68 The wide variety of valves available for different applications means that safety system equipment must also offer a range of choices. Several classifications of valves exist. v vi DESIGNING PRODUCTION SAFETY SHUT-IN SYSTEMS 8 Valve actuators 83 The type of valve actuator that best suits a specific situation depends on the type of power available and the type of operation required. 9 Auxiliary equipment 108 Besides piloting, information feedback, control, and other functions are performed by auxiliary equipment that is used on the valve actuator. 10 Pilot valves 117 Because they receive information then actuate to command another item of equipment, pilot valves are the heart of a safety valve arrangement. Three main types. of pilot valves are used. 11 Other circuit components 152 In addition to safety valves and pilots, other components in the safety system are needed for supply hookup, indication, and isolation. The most important of these circuit components are discussed here. 12 Pilot circuits 162 Piloting circuits assemble the logic functions needed to relate the sensed condition to shutdown. Concepts discussed here for common systems can be extrapolated to other applications. 13 Hydraulic control units 180 The relatively high pressure control signal needed by surface controlled subsurface safety valves and low ratio surface safety valves is normally supplied by a hydraulic control manifold. 14 Subsurface safety valves 200 When the subsurface safety valve is called upon to function, it is protected in the well it seNes. Subsurface safety valves are designed to function under catastrophic conditions. 15 Choosing materials 210 Cost, availability, and strength are three key considerations in selecting the proper material for safety system equipment. Knowledge of each material's advantages and limitations is important. 16 Total system design 227 Components, equipment, and circuits all come together in a system to provide the needed protection. Example problems in this chapter show how total system design must consider all criteria. Index 262