Texas Energy Exploration LLC: Salt-Dome Locations

Salt- Dome Locations in the Gulf Coastal Plain, South-Central United States

ABSTRACT

Information on salt domes in the Gulf of Mexico Coastal Plain, south-central United States and the adjacent Continental Shelf were compiled from major published sources, 1973-84. The location of 624 salt domes is shown on a map at a scale of 1:1,500,000. A color coding system was used to show that the occurrence, size, shape, and location of these domes varies among sources. Two tables of additional data accompany the map and include other available information such as: identifying sources, depth to salt and caprock, diameter, volume, name, and uppermost zone of surrounding sediment that is penetrated, as well as the number of matches between sources. * The locations of salt domes that penetrate specific permeable zones within the gulf coast regional aquifer systems are shown on maps.

INTRODUCTION

The Gulf Coast Regional Aquifer-System Analysis (RASA) covers an area of 230,000 square miles onshore and 60,000 square miles of the adjacent Continental Shelf (fig. 1) (Grubb, 1987). The aquifer system consists of Cenozoic sediments that were divided into aquifers, permeable zones, and confining units (Grubb, 1987, p. 104). This division was accomplished by: 1) Identifying a really extensive units of low permeability; 2) identifying large hydraulic conductivity contrasts between adjacent permeable zones not separated by a regional confining unit; and 3) identifying variations in hydraulic head with depth (Weiss and Williamson, 1985; Weiss, 1990; and Hosman and Weiss, 1988).

PURPOSE AND SCOPE

This study was initiated under the Gulf Coast Regional Aquifer-System Analysis to compile published data on salt domes to the edge of the Continental Shelf. The composite data were compiled to study the possibility of salt domes as a source of salt in brine waters in Cenozoic sediments of the Gulf of Mexico Coastal Plain in the south-central United States and adjacent Continental Shelf (Williamson and others, 1990, p. 107). The shallowest permeable zone penetrated by each dome has been identified in order to assess the possibility of salt dissolution and movement through the permeable zones. In this report, the compiled data are displayed on a map and in a table. Salt-dome locations and geometry were compiled from eight sources, each of which investigated all or part of the study area. Salt-dome name, location, depth to salt and caprock, diameter, volume, and identifying sources used for this compilation are provided in a table.

DISCREPANCIES BETWEEN REFERENCES

Identification of salt dome locations from each of the references used to construct plate 1 are compared in table 1. The discrepancies in dome identification between references are due to several factors. First, the more recent references reflect advances made in seismic surveying and other remote sensing methods of geophysics. Therefore, some structures that were identified by earlier references as salt domes have been reclassified as non-salt structures, whereas other salt domes have been identified for the first time. For this reason, recent references were favored in compiling these data. Second, despite the advancements, identification of salt domes from seismic surveys remains highly subjective (such that two people using the same data may reach different conclusions). Third, the different investigations are based on different databases of raw material and published information. For example, the U.S. Department of the Interior (1983) lists neither Martin (1980) nor Halbouty (1979) as references. Halbouty (1979) lists only those salt domes that have been confirmed by drilling, so that his base list of 343 domes should be considered fundamental. However, Halbouty (1979) also identifies some domes that no other sources identified (for example, Eugene Island Block 231). Finally, the references use different depth criteria for identifying salt domes from deeper salt structures.

Understanding the problem of locating and identifying salt domes from seismic survey data is important because seismic surveys are a major source of information for most of the references used in this report. For example, most of the offshore domes from Martin (1980) were identified from single-channel seismic surveys and gravity surveys. Single-channel seismic analysis does not allow for the differentiation between salt domes and shale plugs (Martin, 1980) because both are piercement structures of similar densities. This may explain the large number of structures (481) that Martin (1980) identified. Additionally, the actual location of salt domes may be blurred because of an effect called sideswipe that allows structures some distance from the map trace of the seismic line to be projected onto the line. Exact salt dome locations can be determined only from a very tight pattern of seismic lines and by correlating seismic surveys with other data.

Dome names and Dome name coding system

Onshore domes are identified by the salt basin in which they are found and their individual names. Offshore domes generally are identified by the name of the offshore area and the block number of the discovery well for the associated oil or gas field. This leads to some confusion in the naming system of offshore domes since some domes do not trap hydrocarbons and so are named for the dome location. Also, some offshore domes cover a portion of several blocks or are associated with several different oil fields. Some domal features were combined if they were named together in one of the sources. Some were split if one of the sources gave two different names.

Some domes lack a published name; these domes are identified on the map by their identifying code being printed in red (plate 1). Dome name coding system is described in the next section. Onshore domes have been given a name for the county or parish in which they are located and a sequential number. Domes in coastal areas, within State waters, are named for the nearest county or parish and a sequential number. Offshore domes have been given a name for their offshore area and the block number in which most of the dome is located.



DOME NAME CODING SYSTEM

Due to space limitations, a letter and number coding system was used to identify each salt dome on the map (plate 1). Offshore domes are symbolized by the offshore block number. Domes without published names have an identifying code printed in red on plate 1. Offshore block numbers increase toward the south within each block. Onshore domes generally are symbolized by four letters from their name. If the name is only one word then the code is the first four letters (example, Race for Raceland). If the name is more than one word then the code is the first letter of each word with the last word filling out the four characters (example, VPar for Valley Park, BdGl for Bayou des Glaizes, and WCBB for West Cote Blanche Bay). If duplicate codes occurred the code was slightly modified, usually the second letter from the first word was added (example, BaHi for Barbers Hill and BiHi for Big Hill). Onshore domes without published names use a similar system for county or parish names with the fourth character occupied by the sequential number (example, JDal for Jefferson Davis 1). Duplicate codes are handled in a similar fashion (example, Jffl for Jefferson County, Texas, and Jefl for Jefferson Parish, Louisiana).

Brookshire Salt Dome Project

We have been in the field for several years now, acquiring minerals, leases, completing title work and legal opinions, land surveys, conducting geological analyses of all data including 3D Seismic, Neozoic geophysical, and then having wells drilled on several of our leases.

The majority of the wells, (over 20), were drilled by industry associates, and have generated significant Oil & Gas sales, as well as proven up the acreage. Also, the new well data has helped to locate reservoirs, faults, etc., all of which now benefits us in the drilling of these offset locations into the newly proven sands, with multiple pay zones.

We believe that this is a truly Golden Opportunity to participate in this modern day Oil & Gas Boom, and many of the offset locations are at the flank, which have historically been the most prolific producers in Salt Domes. Some Salt Dome flanks have produced over 1,000,000 BO per acre!

Spindletop near Beaumont is a prime example of the tremendous potential that Salt Domes can provide, as is the Raccoon Bend Dome just to the north of the Brookshire Salt Dome.

We are very fortunate to have been in the right place at the right time, and to have taken the appropriate action to secure the locations.

Acquisition

Texas Energy Exploration, LLC is a privately owned company that holds oil and gas leases in some of the most desirable locations on the Brookshire Dome, Waller County, Texas.

The leases are in between and directly off setting producing oil and gas wells and known proven reserves. Several successful wells have been drilled on the Texas leases. The drilling success rate in the Brookshire Field over the last several years has shown that 8 out of 10 wells drilled have found reserves of oil and gas above 3,000 ft. The Texas Railroad Commission has set the daily allowable rate of production per well at 300 barrels of oil per day.

Reserves of the Brookshire Dome Miocene gas sand have produced up to 1 BCF of gas at 1,700 ft.(Mosbacher Well). At the current market price of $4.50/mcf for gas, the value of each well would be $4.5 mm.

The Brookshire Dome Field is located in Austin and Waller Counties, Texas, 35 miles west of Houston on and surrounding the I-10 Freeway. The Brookshire salt Dome is one of the largest salt domes located within the gulf coast region of Texas. The cap rock of the Brookshire Salt Dome is 3.5 miles by 4 miles and covers approximately 5,000 acres.

The acreage controlled by Texas Energy Exploration, LLC and the current production locations are south of IH-10 in the southeast and northeast quadrants which are the most productive area’s of the Dome. The terrain is flat to very gently rolling except where bisected by the Brazos River, and Bessie’s Creek. The lands are devoted principally to light agriculture and horse farms.

Geology

The Brookshire Dome is located within the Gulf Coast geological province, which extends 700 miles from the Rio Grande to Florida. Approximately 450 miles of the trend is within Texas. This is one of the most prolific oil and gas producing provinces in the world.

The Gulf Coast is a homocline with regional dip into the Gulf of Mexico. A thick sequence of Cenozoic sediments exceeding, in places, 20,000 feet were deposited across a flat coastal plain. Alternating transgressive and down warping resulted in a series of structurally and stratigraphically important seaward-marching continental/marine "hingeline" trends.

The provenance of Gulf Coast oils are the thick marine shale sections, just seaward of these "hingelines", the cleaner reservoir rocks are in close proximity to these generative shale’s. The result is a series of productive "fairways". These are designated by stratigraphic nomenclature, i.e. the Wilcox, Wilcox-Yegua, Jackson-Yegua, Frio-Vicksburg, Marginulina-Frio and Miocene trends, to name a few.

Accumulation along these trends is controlled by both structure and stratigraphy. Sedimentary downloading and consequent deformation has resulted in a series of normal (down-to-the-coast) fault systems. These growth faults are associated spatially with prominent anticlinal structures in the down-thrown blocks that have formed some of the most prolific Gulf Coast fields. Within these fields, secondary faulting and diverse depositional processes have combined to produce a variety of complicated structural and stratigraphic traps.

Of at least equal importance as hydrocarbon habitat are the various salt domes for which the Gulf Coast is noted. It was, in fact the discovery at Spindletop Salt Dome, in 1901 that opened the modern age of petroleum exploration and production.

Salt domes are pillars of salt which have risen from depth in response to sedimentary deposition and difference in the specific gravities of the salt and overlying (surrounding) sediments. This salt flowage varies extensively from dome to dome; some domes have surface expression, others are deep-seated. Domal shape may vary from straight-sided to mushroom topped with salt "overhangs" which mask the sequence of underlying sands.

In general, salt domes are classified as either "shallow" or "deep" piercement (shallow being those that extend within 2500' of the surface). Salt Domes are associated with prolific oil and gas fields.

Exploration History

Brookshire Dome was identified in 1927 by Gulf Oil Corporation’s seismic reconnaissance. Hydrocarbon production was discovered in 1934 by the Seaport Oil Company #1 Vaughan well in a Frio supercap sand at a depth of 1978'. Reported production was 150 BOPH (flowing). Some geologists consider this area of the dome to be the apex of the Brookshire Salt Dome.

Sporadic drilling occurred throughout the 1940's and 1950's with little success. Oil was discovered on the flank by the Magnolia Petroleum Company #1 Vitek well that drilled through a 3400' salt overhang and completed in an Eocene sand at 5,800 ft.

Additional flank production was established in 1954 by the Humble Oil and Refining #1 Sam Jones well in a 6800' Cockfield sand under the well salt overhand.

In 1952 Humble Oil and Refining completed the #1 P.H. Donigan in a 4560' Cockfield sand for an initial potential of 180 BOPD, 375# FTP. Recorded production from this well totals 15,509 BO.

In 1968 Texaco completed the #1 Donigan Estate in a middle Wilcox sand (10,808' to 852' TVD) for a potential of 38,000 MCFD (AOF). This well recovered a total of 121,892 million standard cubic feet of natural gas. Gas prices in 1968 were .32 cents/mcf. Today gas prices in this field have ranged from $4.00/mcf to over $12.00/mcf over the last several years.

From the 1950’s until 1973 there was very few wells were on the Brookshire Salt Dome. In 1973 Aubrey Rabensburg, who was the chief geologist for John Mecom, Sr. from 1943 until Mr. Mecom retired in 1968. Mr. Rabensburg had discovered over 150 million barrels of oil and gas equivalent, throughout Texas, while working for Mr. Mecom. Mr. Rabensburg wanted to test the Miocene sands at 1,600 t0 1,700 for gas.

Most companies thought the zone contained water, due to conventional logging techniques. Mosbacher Production Co. re-entered an old Kirby Exploration “dry hole” and via a triple combo log perf's in the Miocene sand proved up dry gas reserves.

Brookshire well Locations

Location

The Brookshire Dome Field is located in Austin and Waller Counties, Texas, 35 miles west of Houston on and surrounding the I-10 Freeway.

The Brookshire salt Dome is one of the largest salt domes located within the gulf coast region of Texas. The cap rock of the Brookshire Salt Dome is 3.5 miles by 4 miles and covers approximately 5,000 acres.

The acreage controlled by Texas Energy Exploration, LLC and the current production locations are south of IH-10 in the southeast and northeast quadrants which are the most productive area’s of the Dome. The terrain is flat to very gently rolling except where bisected by the Brazos River, and Bessie’s Creek. The lands are devoted principally to light agriculture and horse farms.

Geology

The Brookshire Dome is located within the Gulf Coast geological province, which extends 700 miles from the Rio Grande to Florida. Approximately 450 miles of the trend is within Texas. This is one of the most prolific oil and gas producing provinces in the world.

The Gulf Coast is a homocline with regional dip into the Gulf of Mexico. A thick sequence of Cenozoic sediments exceeding, in places, 20,000 feet were deposited across a flat coastal plain. Alternating transgressive and down warping resulted in a series of structurally and stratigraphically important seaward-marching continental/marine "hingeline" trends.

The provenance of Gulf Coast oils are the thick marine shale sections, just seaward of these "hingelines", the cleaner reservoir rocks are in close proximity to these generative shale’s. The result is a series of productive "fairways". These are designated by stratigraphic nomenclature, i.e. the Wilcox, Wilcox-Yegua, Jackson-Yegua, Frio-Vicksburg, Marginulina-Frio and Miocene trends, to name a few.