of2011-1262_readme.txt - Chevron Paleontology Files Location and Age of Foraminifer Samples Examined by Chevron Petroleum Company Paleontologists from More Than 2,500 Oil Test Wells in California By Earl E. Brabb 2011 U.S. Geological Survey Open-File Report 2011-1262 (http://pubs.usgs.gov/of/2011/1262/) Explanation for Data Set 1: Scanned images of the original logs for each of the 2,516 wells. The file size for the combined logs is 5.72 gigabytes. Most logs show the depth and character of the formations at various depths and a summary of the most significant microfossils. Many have the lithology and age of each unit plotted on electrical logs for which the author has coined the term 'paleologs'. Many paleologs even indicate the depth of deposition of the various formations. The paleologs in this report were previously not available to the public. Explanation for Data Set 2: Well location and summary for each of the 2,516 paleologs. This spreadsheet in several formats provides information about the well location and a summary of the principal rock and paleontologic units in the well. Column A--Code for the well in both the spreadsheet and the scanned images. Column B--The name of the company or individual responsible for drilling the well. Probably a majority of the names have changed when wells are sold to other companies or individuals. These changes make the search for Division of Oil, Gas and Geothermal Resources (DOGGR) data about the wells difficult. Data for a few wells in the database may not be correct. Column C--Name of the landowner or person with drilling rights (lease-holder). Many of these names have changed. Column D--Number for the well. Some wells acquired by another company are given a different number from the number on the paleolog. Column E--Section number, 1 to 36, a part of the Public Land Survey System (PLSS) used in California. The land survey is also called the Federal Township and Range System (FTRS). Column F--Township (PLSS). Column G--Range (PLSS). Column H--Meridian (PLSS). Three Meridians are used; Humboldt (HU) in northern California; Mount Diablo (MD) used in northern and central California; and SB (Santa Barbara) used in Southern California. Column I--American Petroleum Institute (API) number for the well. This number is unique to all oil wells in the United States. Column J--Name of U.S. Geological Survey 7.5' quadrangle where the well is located. Most quadrangle names were obtained by examining the PLSS for the well on 1:100,000- scale topographic maps. Column K--Latitude from the DOGGR file. This coordinate uses the NAD27 datum. Column L--Longitude from the DOGGR file. This coordinate uses the NAD27 datum. Column M--Paleontology (paleo) date. The date when the Chevron paleontologist established the ages of geologic units in a well. Column N--Indicates if the paleolog is based on an electric log (Y) or lacks an electric log (N). Column O--The number of the DOGGR District where the well is located. District 4 is divided into two parts, 4p1 and 4p2. Column P--Description of the units in a well. The age and formation name of the principal stratigraphic units in the well followed by the depth to the top and(or) bottom of the units, in feet. Lithologic units: ss, sandstone; sh, shale; sls, siltstone. Most of these lithologies are inferred by the author of this report mainly from electrical logs and secondarily from lithologic data on the paleolog or data in the file folder. Many of the units in wells were inferred by the Chevron paleontologists from information in wells nearby or from so-called standard wells with good faunas. Brown Shale is used as a formation name in several wells but the lithology may not be shale. Other names may not be consistent in lithology from one well to another. Column Q--Total depth of the well as noted on the paleolog, in a DOGGR database, or on a DOGGR map. Many wells were redrilled after the paleologs were prepared, so that a search for total depth in the DOGGR databases may not provide the correct name, location, or other data for the well.