问答题 翻译：Traps of this type were formed after the deposition of the reservoir rock by erosion and/or alteration of a portion of the reservoir rock through solution or chemical replacement.

问答题 翻译：The casing and tubing used to bring crude oil to the surface is suspended underneath a wellhead or Christmas tree.

问答题 翻译：Other instruments used in gravity work are the torsion balance and the pendulum.These instruments, however, have been practically replaced by the gravimeter.