368 The Philippine Journal of Science ma 



In the local field a distinction must be made between those 

 anticlines in which erosion has left the possible productive 

 horizons intact across the arch and those in which erosion has 

 proceeded along the crest until the oil-bearing strata have been 

 cut through. Where the oil-bearing rocks are preserved across 

 the anticline, oil — or gas — would be expected in the crest of the 

 fold and wells should be located so as to explore the crest first. 

 Where the productive beds are cut through along the crest and 

 their edges exposed in the limbs of the anticline, the petroleum 

 may be supposed to have escaped from outcrops along the axis 

 and wells should be driven on the flanks of the fold in the hope 

 of encountering a natural reservoir which does not appear at 

 the surface and, consequently, has not been drained by seepage 

 from its outcrop. 



The anticlines in Bondoc Peninsula are generally asymetric; 

 that is, one limb is steeper than the other. In drilling on an 

 anticline of this character the limb with the lesser inclination 

 affords better opportunity for exploration than the steeper limb. 

 It is probably true, also, that the gentler limb of a sharp 

 asymmetric anticline more generally has been found to be pro- 

 ductive than the steeper limb. 



The Maglihi anticline is probably the most suitable territory 

 for the initial exploration of this field. The structure is favor- 

 able in that an anticlinal fold exists, although the anticline is 

 more acute than would generally be considered desirable, and 

 the petroleum-bearing strata are intact generally along its axis. 

 The presence of petroleum in this anticline is established by the 

 seeps at Banco, at Bahay, and on Milipilijuan Creek. 



In the matter of the actual location of prospect wells, the 

 factor of comparative accessibility will demand attention. The 

 Maglihi anticline appears to be most favorable in structure near 

 Mount Morabi. It would be desirable to have several test wells 

 drilled through the crest and the western limb of the fold in 

 this vicinity. The eastern limb should also be explored, but 

 in it the strata dip very steeply, and the best location for the 

 first wells would be difficult to determine exactly. The vicinity 

 of Mount Morabi is relatively inaccessible as compared with 

 Bahay farther north along the same flexure. The valley along 

 the anticlinal crest near Mount Morabi is at least 250 meters 

 above sea level, and the distance to the coast is about 6 kilo- 

 meters. 



At Bahay the anticline is not so clearly revealed as it is near 

 Mount Morabi, and the structure may be less favorable, although 

 the general conditions are similar. It would be feasible to 



