Identifier: califoilgasyield00wattrich (find matches)
Title: Oil and gas yielding formations of California
Year: 1900 (1900s)
Authors: Watts, William Lord, b. 1850
Subjects: Natural gas Petroleum
Publisher: Sacramento, A.J. Johnston, superintendent State printing
Contributing Library: University of California Libraries
Digitizing Sponsor: Kahle/Austin Foundation and Omidyar Network

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87 with OM, the axis of the fold. Unless the structure of the formationwere known, it would naturally be supposed that the dip of the oil-sandstratum was fully shown by the exposed rocks at point K. If well Gwere drilled, the oil-sand would be struck at point I, and the oil-sandstratum would be penetrated lengthwise between I and N. This wouldlead to the erroneous conclusion that a very thick stratum of oil-sandhad been penetrated. If well J were drilled with the intention of strik-ing the oil-sand at 0, it is obvious that the oil-sand would be missedaltogether. This illustrates the advisability of exhausting all the evi-dence in sight concerning the structural geology of a locality before wellsare located. 12.4.5. It is quite probable that in many instances the dip of stratagreatly increases at short distances from anticlinal axes. Moreover, asthe axis of a syncline is approached, the strata may be pushed over sothat they dip backward toward the axis of the anticline, giving the fold
Text Appearing After Image:
Fan-shaped Fold.Pig. 18. a fan-shaped structure, as shown on the right in Fig. 18. If oil-yieldingformations were folded in this manner, it is obvious that, although theoil-sand mighi be struck at a reasonable depth near the axis of theanticline, as in the case of wells A and B, Fig. 18, a very short distancefarther down the slope of the fold the oil-sand might plunge to so greata depth that it could not be profitably reached by the drill. 12.4.6. Photos 33, 34, and 35 illustrate the plication met with in theCoast Ranges. Photo 33 looks like an upright fold, especially at the pointphotographed. Investigation showed that the strata forming the sideof the fold on which the derrick is situated dip at a less angle than dothe strata on the opposite side of the fold. The fold is, therefore, slightlyinclined. Photo 34 is a good representation of an inclined fold. Photo 35 188 CALIFORNIA STATE MINING BUREAU. illustrates the contortions to which rocky strata are subjected, and ofwhich the over

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