The Bovallius field, located in the southeastern part of Trinidad is bordered to the west by the Balata East block and to the south by the Ortoire block. The field spans approximately 942 acres with six wells drilled in the block to date, the first well being drilled in 1954. Regionally the Bovallius field occurs on trend with a WSW plunging, SE verging thrusted anticlinal system. The major tectonic features within the Bovallius field consists of the eastern extension of the Balata anticline which is truncated by several NE-SW trending thrust faults, several NW-SE trending normal faults and bordered to the east by the NE-S/SW Cedar Grove fault. Previous evaluations done on the Bovallius field resulted in little prospectivity for the block. Recent discovery wells within the Ortoire Block, created renewed interest over the Bovallius field. It is known from analogous fields that there are three structural limbs which occur in the Herrera formation: Overthrust, Intermediate and Sub-thrust. Field wide mapping indicated that most of the wells within the Bovallius field penetrated three thrust sheets within the Overthrust limb only. As such the undrilled Intermediate and Sub-thrust limbs present an exploration opportunity within the field. Sand maps constructed on the producing reservoirs show that these sands trend in a NE-SW direction with the thickest accumulations occurring sub-parallel to the axis of the anticline. Similarly, as seen in the Penal/Barrackpore and Cascadura fields, within the Bovallius field the anticlinal system plunges to the SW with NW-SE trending normal faults dissecting the anticlinal feature. The most prospective areas tend to be in the eastern crestal structurally up-dip parts of these fault blocks. This updated model resulted in three outstep prospects. Field development in the southern part of the Bovallius block was heavily influenced by Balata East wells, BE-6, and BE-19. These wells are located on the southern flank of the Balata anticline and encountered the Herrera sands wet. At the time it was believed that as the majority of the Bovallius block lies downdip of these wet wells, the Herrera sands would also be wet over this acreage. However, on examination of some of the surrounding wells in the area, this assumption has been relooked. There is a thrust fault running in a NE-SW direction, south of the wet Balata wells which allow for hydrocarbon accumulation within the OL-4/Royston area. This makes the southern part of the Bovallius block prospective for the Herrera sands.

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