ALTA VISTA, PHILTOP AND RINEHART OIL FIELDS,
BEXAR COUNTY, TEXAS
Mark E. Thompson
The oil and gas industry knows the names of many of the Bexar County oil fields and that they are old and shallow, but little has been published on them recently and the geology and history of these fields is no longer well known. One of the ear-ly discoveries was south of San Antonio where drilling in the Alta Vista oil field and surrounding area from 1901 to 1935 provided geological infor-mation that helped early Texas geologists decipher the subsurface stratigraphy and structure of south-ern Bexar County. Descriptions of early drilling results at Alta Vista are presented which provide insight into how some of these early geological ide-as were formulated. The studies of the geology at Alta Vista led to additional drilling and the oil dis-covery at adjacent Philtop field. Recognition of the distinction in the subsurface between the Austin Chalk and the overlying Anacacho Limestone prompted the discovery and development of Rine-hart oil field.
Detailed structural mapping at Rinehart, Philtop and Alta Vista fields is presented which il-lustrates how the three fields are interconnected along the up thrown side of the large Alta Vista fault.
Oil exploration has been in progress in the vicinity of the Rinehart field for over 100 years and yet targets for additional drilling still exist. New cultural development on the surface as the city of San Antonio moves ever southward into this area creates a challenge for any future exploration plans.