Acid Bottle Method of Subsurface Well Survey and Its Application

Abstract

The surveying of oil wells has in recent months become a common practice inthe deep fields of the Mid-Continent area. Borehole surveys have been made bymining companies for many years, but the introduction of such methods into theoil fields has been delayed until the past few years, because the value ofsurvey data was not fully appreciated. The acid and gelatin bottle methods of obtaining the angle of deviation andthe floating compass method of obtaining the direction of horizontal drift havebeen in use for more than 20 years. A photographic recording instrumentconsisting of a plumb bob, magnetic needle and electrically operated camera wasdevised and used in the Rand mining fields of South Africa prior to 1912.Another and improved photographic instrument, depending upon orientation of thedrill pipe instead of polar magnetism for direction, has been invented andused. The acid bottle method has also been used in conjunction with orienteddrill pipe. The magnetic compass is not reliable for oil-well work because ofthe unsymmetrical attraction of the needle to the well casing and possiblemagnetic formations. Many engineers also concur in the opinion that orientationof the drill pipe from instrument to surface will be inaccurate because of thetorque exerted between the drill pipe and walls of the hole, causing the lowersections of pipe to twist. When it is considered that 4000 ft. of 6 in. drillpipe has approximately the same slenderness ratio as 6 ft. of silk thread, suchtwisting effects can be readily visualized. The gyroscopic compass has beensuggested for use in direction finding, but the high cost of such instrumentswill prohibit their use, except in special cases. Due to the lack of accurate direction-finding instruments, almost all of thesurvey work in the Mid-Continent fields has been of the acid bottle methodalone.