hadehalf edge layerhalf turn sockethammerhand drilled wellhand drivehand pumphandtighthang a well offhanger flangehanging rodhanging wallhard facinghard formationhard formation bithard formation rollerhard radiationhard rockhardened cementhay tankhazardous rockhead of warerheaderheat conductivityheating coilheave compensationheaving shaleheavy crudeheavy gradientheavy hydrocarbonheavy mudheavy stratificationheel of slopeheelshelicopter refuelling systemhelideckhercynian foldingheterogeneous rockhexagonal kellyhexagonal patternhigh angle holehigh linehigh ph mudhigh pressure cement pumphigh pressure fluidhigh pressure gas drivehigh pressure mud pumphigh pressure valvehigh pressure wellhigh resistivity bed