Wilcox formation

This paper presents a summary of the history, geology, and development of the Slick-Wilcox field, DeWitt and Goliad counties, Texas, from its discovery until April, 1947. The Slick-Wilcox field is located on the DeWitt-Goliad County line southeast of the town of Nordheim. The surface is underlain by southeasterly dipping Tertiary beds. Oil was discovered in the “Pettus” sand in the Cockfield member of the Yegua formation in December, 1930. Discovery was the result of surface structural mapping. Shallow “Pettus” production was largely abandoned after 1937, and deeper oil was produced from the third sand of the upper Carrizo-Wilcox section in May, 1943. Location for the well which discovered the deeper producing sand was made from subsurface information gained from geophysical prospecting. The accumulation of oil occurs in a faulted dome. The oil is trapped against a normal fault upthrown on the north. The oil is being produced by a combination of the forces resulting from a natural water drive and an expanding gas cap. There are 48 producing oil wells in the field. By the end of March, 1947, the field has produced 4,339,599 barrels of oil from the producing zone in the Carrizo-Wilcox. The original recoverable reserve is estimated at 20,000,000 barrels of oil.

@article{sebring1948slickwilcox,
    author = "Sebring, Louie",
    title = "Slick-Wilcox Field, Dewitt and Goliad Counties, Texas",
    year = "1948",
    journal = "AAPG Bulletin",
    abstract = "This paper presents a summary of the history, geology, and development of the Slick-Wilcox field, DeWitt and Goliad counties, Texas, from its discovery until April, 1947. The Slick-Wilcox field is located on the DeWitt-Goliad County line southeast of the town of Nordheim. The surface is underlain by southeasterly dipping Tertiary beds. Oil was discovered in the “Pettus” sand in the Cockfield member of the Yegua formation in December, 1930. Discovery was the result of surface structural mapping. Shallow “Pettus” production was largely abandoned after 1937, and deeper oil was produced from the third sand of the upper Carrizo-Wilcox section in May, 1943. Location for the well which discovered the deeper producing sand was made from subsurface information gained from geophysical prospecting. The accumulation of oil occurs in a faulted dome. The oil is trapped against a normal fault upthrown on the north. The oil is being produced by a combination of the forces resulting from a natural water drive and an expanding gas cap. There are 48 producing oil wells in the field. By the end of March, 1947, the field has produced 4,339,599 barrels of oil from the producing zone in the Carrizo-Wilcox. The original recoverable reserve is estimated at 20,000,000 barrels of oil.",
    url = "https://doi.org/10.1306/3d933af1-16b1-11d7-8645000102c1865d",
    doi = "10.1306/3d933af1-16b1-11d7-8645000102c1865d",
    number = "2",
    pages = "228-251",
    volume = "32"
}

@article{hoyt1959erosional,
    author = "Hoyt, William V.",
    title = "Erosional Channel in Middle Wilcox Near Yoakum, Lavaca County, Texas: ABSTRACT",
    year = "1959",
    journal = "AAPG Bulletin",
    url = "https://doi.org/10.1306/0bda5efa-16bd-11d7-8645000102c1865d",
    doi = "10.1306/0bda5efa-16bd-11d7-8645000102c1865d",
    volume = "43"
}

@article{hoyt1959erosional3,
    author = "Hoyt, W. V",
    title = "Erosional channel in the Middle Wilcox near Yoakum, Lavaca County, Texas",
    year = "1959",
    journal = "Gulf Coast Association of Geological Societies Transactions, v. 9, p. 41-50",
    note = "talkorigins\_source = {true}; raw\_reference = {Hoyt, W. V., 1959, Erosional channel in the Middle Wilcox near Yoakum, Lavaca County, Texas: Gulf Coast Association of Geological Societies Transactions, v. 9, p. 41-50.}"
}

Fashing field, as presently defined, is 10 miles long and 2 miles wide. The field extends from the southeast corner of Atascosa County to the northwest corner of Karnes County, approximately 50 miles southeast of San Antonio, Texas. Lone Star Producing Company discovered gas in the Edwards limestone (Lower Cretaceous) at Fashing in July, 1956, when its No. 1-A L. T. Urbanczyk well reach the top of the Edwards at 10,210 feet and found 580 feet of productive section that had an initial potential of 26,000 MCFGPD plus 24 barrels of 50.6° gravity distillate per MMCF. The Edwards structure at Fashing field is dominated by a simple, northeast-trending up-to-the-coast fault with effective closure against the high side. This fault has a maximum vertical displacement of approximately 700 feet at the Edwards level, which decreases to a maximum of 320 feet going up the section to the Carrizo Sand (Eocene) level. The fault is responsible for the Weigang field oil production at the Carrizo level. The fault dips northwest, with the angle of dip decreasing from 50° at the Carrizo to 38° at the Edwards. Edwards gas production at Fashing comes from two separate zones called the “A” and “B” zones, respectively. The “A” zone has an average porosity of 15.5 per cent, an average permeability of 12.6 millidarcys, and an average connate water saturation of 28 per cent. The “B” zone has an average porosity of 13.2 per cent, an average permeability of 4.4 millidarcys, and an average connate water saturation of 24 per cent.

@article{keahey1962fashing,
    author = "Keahey, Robert A.",
    title = "Fashing Field, Atascosa-Karnes Counties, Texas",
    year = "1962",
    journal = "AAPG Bulletin",
    abstract = "Fashing field, as presently defined, is 10 miles long and 2 miles wide. The field extends from the southeast corner of Atascosa County to the northwest corner of Karnes County, approximately 50 miles southeast of San Antonio, Texas. Lone Star Producing Company discovered gas in the Edwards limestone (Lower Cretaceous) at Fashing in July, 1956, when its No. 1-A L. T. Urbanczyk well reach the top of the Edwards at 10,210 feet and found 580 feet of productive section that had an initial potential of 26,000 MCFGPD plus 24 barrels of 50.6° gravity distillate per MMCF. The Edwards structure at Fashing field is dominated by a simple, northeast-trending up-to-the-coast fault with effective closure against the high side. This fault has a maximum vertical displacement of approximately 700 feet at the Edwards level, which decreases to a maximum of 320 feet going up the section to the Carrizo Sand (Eocene) level. The fault is responsible for the Weigang field oil production at the Carrizo level. The fault dips northwest, with the angle of dip decreasing from 50° at the Carrizo to 38° at the Edwards. Edwards gas production at Fashing comes from two separate zones called the “A” and “B” zones, respectively. The “A” zone has an average porosity of 15.5 per cent, an average permeability of 12.6 millidarcys, and an average connate water saturation of 28 per cent. The “B” zone has an average porosity of 13.2 per cent, an average permeability of 4.4 millidarcys, and an average connate water saturation of 24 per cent.",
    url = "https://doi.org/10.1306/bc743919-16be-11d7-8645000102c1865d",
    doi = "10.1306/bc743919-16be-11d7-8645000102c1865d",
    number = "10",
    pages = "1965-1965",
    volume = "46"
}

Fashing field, as presently defined, is 10 mi long and 2 mi wide. The field is in the deep Edwards fault trend and extends from the southeast corner of Atascosa County to the northwest corner of Karnes County, approximately 50 mi southeast of San Antonio, Texas. Lone Star Producing Co. discovered gas in the Edwards Limestone (Lower Cretaceous) at Fashing in July 1956 when their No. 1-A L. T. Urbanczyk well reached the top of the Edwards at 10,210 ft and found 580 ft of productive section that had an initial potential of 26 million cu ft of gas a day and 24 bbls of 50.6°- gravity distillate per million cubic feet. The Edwards structure at Fashing field is dominated by a simple, northeast-trending up-to- the-coast fault with effective closure against the upthrown side. This fault has a maximum vertical displacement of approximately 700 ft at the Edwards level, which decreases upward to a maximum of 320 ft at the Carrizo Sand (Eocene) level. The fault traps the Weigang field oil accumulation at the Carrizo level. The fault dips northwestward, with the angle of dip decreasing from 50° at the Carrizo to 38° at the Edwards. Edwards gas production at Fashing is from two separate zones called the A and B Zones, respectively. The A Zone has an average porosity of 15.5 per cent, an average permeability of 12.6 md, and an average connate water saturation of 28 per cent. The B Zone has an average porosity of 13.2 per cent, an average permeability of 4.4 md, and an average connate water saturation of 24 per cent.

@incollection{keahey1968fashing,
    author = "Keahey, Robert A.",
    title = "Fashing Field, Atascosa-Karnes Counties, Texas",
    year = "1968",
    booktitle = "Natural Gases of North America, Volumes 1 \& 2",
    abstract = "Fashing field, as presently defined, is 10 mi long and 2 mi wide. The field is in the deep Edwards fault trend and extends from the southeast corner of Atascosa County to the northwest corner of Karnes County, approximately 50 mi southeast of San Antonio, Texas. Lone Star Producing Co. discovered gas in the Edwards Limestone (Lower Cretaceous) at Fashing in July 1956 when their No. 1-A L. T. Urbanczyk well reached the top of the Edwards at 10,210 ft and found 580 ft of productive section that had an initial potential of 26 million cu ft of gas a day and 24 bbls of 50.6°- gravity distillate per million cubic feet. The Edwards structure at Fashing field is dominated by a simple, northeast-trending up-to- the-coast fault with effective closure against the upthrown side. This fault has a maximum vertical displacement of approximately 700 ft at the Edwards level, which decreases upward to a maximum of 320 ft at the Carrizo Sand (Eocene) level. The fault traps the Weigang field oil accumulation at the Carrizo level. The fault dips northwestward, with the angle of dip decreasing from 50° at the Carrizo to 38° at the Edwards. Edwards gas production at Fashing is from two separate zones called the A and B Zones, respectively. The A Zone has an average porosity of 15.5 per cent, an average permeability of 12.6 md, and an average connate water saturation of 28 per cent. The B Zone has an average porosity of 13.2 per cent, an average permeability of 4.4 md, and an average connate water saturation of 24 per cent.",
    url = "https://doi.org/10.1306/m9363c68",
    doi = "10.1306/m9363c68",
    pages = "976-981"
}

@incollection{chuber1972milbur,
    author = "Chuber, Stewart",
    title = "Milbur (Wilcox) Field, Milam and Burleson Counties, Texas",
    year = "1972",
    booktitle = "Stratigraphic Oil and Gas Fields—Classification, Exploration Methods, and Case Histories",
    url = "https://doi.org/10.1306/m16371c27",
    doi = "10.1306/m16371c27"
}

@article{berg1973deepwater1,
    author = "Berg, R. R. and Findley, R",
    title = "Deep-water interpretation of Upper Wilcox sandstones from core study, Katy Field, Texas",
    year = "1973",
    journal = "Gulf Coast Association of Geological Societies Transactions, v. 23, p. 259-265",
    note = "talkorigins\_source = {true}; raw\_reference = {Berg, R. R., and Findley, R., 1973, Deep-water interpretation of Upper Wilcox sandstones from core study, Katy Field, Texas: Gulf Coast Association of Geological Societies Transactions, v. 23, p. 259-265.}"
}

@article{berg1977characteristics2,
    author = "Berg, R. R. and Tedford, F. J",
    title = "Characteristics of Wilcox gas reservoirs, Northeast Thompsonville Field, Jim Hogg and Webb Counties, Texas",
    year = "1977",
    journal = "Gulf Coast Association of Geological Societies Transactions, v. 27, p. 6-19",
    note = "talkorigins\_source = {true}; raw\_reference = {Berg, R. R., and Tedford, F. J., 1977, Characteristics of Wilcox gas reservoirs, Northeast Thompsonville Field, Jim Hogg and Webb Counties, Texas: Gulf Coast Association of Geological Societies Transactions, v. 27, p. 6-19.}"
}

@article{robertrberg1977characteristics,
    author = "Robert R. Berg, Frederick J. Tedfor",
    title = "Characteristics of Wilcox Gas Reservoirs, Northeast Thompsonville Field, Jim Hogg and Webb Counties, Texas: ABSTRACT",
    year = "1977",
    journal = "AAPG Bulletin",
    url = "https://doi.org/10.1306/c1ea45d6-16c9-11d7-8645000102c1865d",
    doi = "10.1306/c1ea45d6-16c9-11d7-8645000102c1865d",
    volume = "61"
}

@article{berg1979characteristics,
    author = "Berg, Robert R.",
    title = "Characteristics of Lower Wilcox Reservoirs, Valentine Field, Lavaca County, Texas: ABSTRACT",
    year = "1979",
    journal = "AAPG Bulletin",
    url = "https://doi.org/10.1306/2f918711-16ce-11d7-8645000102c1865d",
    doi = "10.1306/2f918711-16ce-11d7-8645000102c1865d",
    volume = "63"
}

@article{henke1985reservoir,
    author = "Henke, Kim A.",
    title = "Reservoir Characteristics of Lower Wilcox Sandstones, Lobo Trend, Webb and Zapata Counties, Texas: ABSTRACT",
    year = "1985",
    journal = "AAPG Bulletin",
    url = "https://doi.org/10.1306/ad461fac-16f7-11d7-8645000102c1865d",
    doi = "10.1306/ad461fac-16f7-11d7-8645000102c1865d",
    volume = "69"
}

@article{miller1991lower,
    author = "{MILLER, RANDALL S., Reservoirs, Inc}",
    title = "Lower Wilcox Submarine Canyon Channel Sandstones, Sheridan Field, Colorado County, Texas",
    year = "1991",
    journal = "AAPG Bulletin",
    url = "https://doi.org/10.1306/0c9b2051-1710-11d7-8645000102c1865d",
    doi = "10.1306/0c9b2051-1710-11d7-8645000102c1865d",
    volume = "75"
}

A water-base drilling fluid treated with a special additive has successfully replaced the diesel oil base muds (DOBM) on a series of wells drilled in the South Texas Lower Wilcox formation. Until recently, a relaxed fluid loss DOBM mud was used in this hole interval because It provided improved hole stability and higher penetration rates at favorable economics. The only problem the DOBM mud did not solve was environmental. The cuttings were coated with oil and high salinity brine and therefore had to be treated before they could be disposed of locally. Efforts to find an environmentally safe DOBM mud replacement have resulted in the development of a special additive for water base muds. It offers a significant reduction in total well cost by increasing the rate of penetration and reducing the mud and cuttings disposal costs. This paper will discuss the field development and use of this special drilling fluid additive that provides improved performance characteristics when compared to traditional, economic, environmentally safe water-based mud systems. Over 45 wells have been drilled with this new water-base drilling fluid additive. In some areas, the average rate of penetration, including connection time, has increased 30% over the DOBM average. The rotating hours required to drill an interval from 1500 - 3000 feet in length with 14.0 - 16.0 ppg mud have been reduced accordingly. Total well costs have been reduced by 20 percent. The authors provide data on how to optimize water-base mud formulations, special additive maintenance treatments, mud solids management and bit performance utilized on this successful South Texas drilling program.

@inproceedings{hasley1994oil,
    author = "Hasley, J. R. and Dunn, K. E. and Reinhardt, W. R. and Carter, T. S. and Duncan, W. M.",
    title = "Oil Mud Replacement Successfully Drills South Texas Lower Wilcox Formation",
    year = "1994",
    booktitle = "IADC/SPE Drilling Conference",
    abstract = "A water-base drilling fluid treated with a special additive has successfully replaced the diesel oil base muds (DOBM) on a series of wells drilled in the South Texas Lower Wilcox formation. Until recently, a relaxed fluid loss DOBM mud was used in this hole interval because It provided improved hole stability and higher penetration rates at favorable economics. The only problem the DOBM mud did not solve was environmental. The cuttings were coated with oil and high salinity brine and therefore had to be treated before they could be disposed of locally. Efforts to find an environmentally safe DOBM mud replacement have resulted in the development of a special additive for water base muds. It offers a significant reduction in total well cost by increasing the rate of penetration and reducing the mud and cuttings disposal costs. This paper will discuss the field development and use of this special drilling fluid additive that provides improved performance characteristics when compared to traditional, economic, environmentally safe water-based mud systems. Over 45 wells have been drilled with this new water-base drilling fluid additive. In some areas, the average rate of penetration, including connection time, has increased 30\% over the DOBM average. The rotating hours required to drill an interval from 1500 - 3000 feet in length with 14.0 - 16.0 ppg mud have been reduced accordingly. Total well costs have been reduced by 20 percent. The authors provide data on how to optimize water-base mud formulations, special additive maintenance treatments, mud solids management and bit performance utilized on this successful South Texas drilling program.",
    url = "https://doi.org/10.2118/27539-ms",
    doi = "10.2118/27539-ms"
}