The term as sources define it, the energy they describe, what the Department of Energy Gulf Coast program reported, the limits it reported, and its budget by year.
The term
"Geopressured geothermal" describes deep reservoirs in sedimentary basins where the fluid is held at pressures above the normal hydrostatic gradient; sources describe them as holding hot brine with dissolved methane.
Gradient criteria differ by source. The Bureau of Economic Geology (1982) and the U.S. Geological Survey (1979) describe the normal gradient as about 0.465 psi per foot. BEG picked the top of geopressure in the Wilcox trend of the Texas Gulf Coast at about the depth where the gradient reaches 0.7 psi per foot. A National Renewable Energy Laboratory study (2012) used, as its working definition, a brine reservoir above 212 degrees F with a gradient above 0.7 psi per foot.
Sources: Circular 790, USGS; Report of Investigations 117, BEG; Properties of Geopressured Brines and Wells, INEL; Recoverable Resource Estimate, NREL; Research Program Overview, DOE. Read October 4, 2026.
| Source and year | What it calls normal | What it calls geopressured |
|---|---|---|
| USGS, Circular 790, 1979 | About 0.465 psi per foot (10.5 kPa per meter). | Rock with pore fluid pressure above normal. No threshold is stated in the passage. |
| Bureau of Economic Geology, 1982 | 0.465 psi per foot, hydrostatic. | Top of geopressure picked at about the depth where the gradient reaches 0.7 psi per foot, which the abstract considers the "operational" top. |
| Idaho National Engineering Laboratory for DOE, 1989 | 0.465 psi per foot in the Gulf Coast area. | Gradients in excess of normal. A 1989 abstract says pressures have been measured as high as 1.05 psi per foot in the Gulf Coast area. It is a measured maximum, not a threshold. |
| NREL, 2012 | Not stated in the abstract. | A study definition: above 0.7 psi per foot and brine hotter than 212 degrees F, used to screen identified onshore sites in Texas and Louisiana. |
Three kinds of energy that sources describe
A 1979 USGS assessment of the northern Gulf of Mexico basin said the fluid resource base in place consists of thermal energy, mechanical energy and the energy of the methane dissolved in the water.
- Heat
Thermal energy, in the heated brine.
- Pressure
USGS calls this mechanical energy. In its passage on the Pleasant Bayou plant, the DOE history chapter calls it hydraulic energy, in high-pressured fluids.
- Dissolved methane
Chemical energy, in natural gas dissolved in the brine.
A chapter of the same 1979 circular does not calculate mechanical energy, because a 1975 USGS assessment showed it to be negligible. A 2012 NREL abstract lists two sources of energy, methane and heat. The DOE history says a hybrid system takes advantage of all three forms, and that the installed Pleasant Bayou system used valves in place of a hydraulic turbine to reduce wellhead pressure.
Sources: Circular 790, USGS; Recoverable Resource Estimate, NREL; Geothermal History, Reservoir Engineering, Section 3.0, DOE. Read October 4, 2026.
What the DOE Gulf Coast program did
The DOE Geopressured-Geothermal Energy program ran from the mid 1970s to the early 1990s. The DOE history chapter on reservoir engineering (published September 2010, covering 1976 to 2006, called "the chapter" below) says it was intended to evaluate the extent and viability of geopressured geothermal resource development using test data from both new and existing wells. Its well testing program had two parts.
- Wells of opportunity were industry wells that proved uneconomic for oil or gas but were known to have penetrated geopressured reservoirs. A 1989 DOE overview says DOE assumed liability for their final disposition from the owners in exchange for the right to study the geopressured zones. The chapter says they were used only for short tests, typically less than a month.
- Design wells were drilled with DOE funding on potentially favorable prospects and given long-term tests. The chapter names five sites, four in Louisiana and one in Texas.
The 1989 DOE overview says that, given limitations such as wellbore diameter, which restricts flow rate, wells of opportunity are mainly useful as indicators of resource potential, and that DOE also drilled wells expressly designed to tap geopressured aquifers.
Test history
These are demonstration and test numbers from named wells. They are history, not what any project would have.
Pleasant Bayou hybrid plant
In 1989 DOE and the Electric Power Research Institute co-funded a demonstration of a hybrid power plant concept at the Pleasant Bayou test facility in Brazoria County, Texas. The chapter says the plant ran from October 1989 to the end of May 1990, and was shut down a month early because the brine injection well required rework. The chapter's text says the plant produced about 1 MW of power from 10,000 barrels per day of 143 degrees C (290 degrees F) brine. The chapter's unit is MW, with no e or t added. The figure on the chapter's schematic of the hybrid power system shows a gas engine at 650 kW and a binary cycle at 541 kW, a total of 1,191 kW. That total is gross power production. The same schematic lists design parasitic loads of 209 kW and net power of 982 kW, and its caption says the actual total load varied from 260 to 306 kW.
Scale and the Gladys McCall flow test
The chapter's scaling section is about calcium carbonate scale, a mineral deposit. Production tubing at Pleasant Bayou was found scaled to a thickness of 0.5 inches down to 3,700 meters (12,000 feet) after a series of production tests. At Gladys McCall No. 1 in Cameron Parish, Louisiana, a figure caption gives a build-up rate of 19,400 pounds of scale per million barrels of brine produced. The chapter's text gives 20,000 pounds per million barrels. The text also says a treatment controlled scale formation in the wellbore, and that 13.3 million barrels of brine were then produced with little or no scale build-up. That well's flow test produced over 27 million barrels of hot (143 degrees C, 290 degrees F) brine.
The Hulin well and reworked wells
The chapter says the Hulin well provided an example of the feasibility of using a reworked oil or gas well for geopressured geothermal production. It also says well depth and tubing size were the limiting factors in production efficiency, with estimated production rates of only 15,000 to 18,000 barrels per day. It says similar well bore limitations were typical for other depleted wells that were recompleted for geopressured geothermal production, and that, as a result, high production rates of 40,000 barrels per day from existing reworked wells could not be assumed even with excellent reservoir conditions. It calls the Willis Hulin No. 1 the deepest, hottest and highest pressure Well of Opportunity.
The whole range of the test wells
Table 7 of the chapter lists 11 wells of opportunity. Table 8 lists five rows for design wells: Gladys McCall appears in two rows, and Lafourche Crossing, one of the five sites the text names, has no row. The chapter's tables print temperature in degrees C only, so the degrees F values are our conversions (degrees F = degrees C x 9/5 + 32), rounded and approximate.
| Measure, lowest to highest | Wells of opportunity (11 wells) | Design wells (5 table rows) |
|---|---|---|
| Brine temperature | 112 to 182 degrees C (about 234 to 360 degrees F) | 114 to 150 degrees C (about 237 to 302 degrees F) |
| Gas to brine ratio, in standard cubic feet per standard barrel (SCF/STB), the chapter's key | 24.0 to 55.7 SCF/STB | 24.0 to 34.0 SCF/STB |
| Flow rate | 1,950 to 15,000 barrels per day. One well lists none. | 10,000 to 36,500 barrels per day |
The chapter also reports an estimate that about 250 trillion cubic feet of gas on average could potentially be extracted from the resources in the area DOE focused on. It gives no range. The sentence begins "Twenty years later", after a reference to the late 1960s, so it is an older estimate. This is an estimate in the chapter. It is not a forecast, and this page does not apply it to any place.
Sources: Geothermal History, Reservoir Engineering, Section 3.0, DOE (2010); Research Program Overview, DOE (1989). Read October 4, 2026.
What the DOE chapter lists as the program's findings
The DOE history chapter (2010) ends its Gulf Coast section with a list of the program's significant accomplishments. The middle column gives the chapter's words. The right-hand column is our reading of what each item names and does not name. These are program-level statements about DOE test wells. They are not a forecast for any project, county or parcel.
| Item | The chapter's words | What the item covers |
|---|---|---|
| 1 | "Identification of geopressured-geothermal onshore fairways in Louisiana and Texas" | The chapter names no parishes or counties for the fairways in the text. |
| 2 | "Determination that high brine flow rates (20,000 to 40,000 barrels per day) could be sustained for long periods of time using appropriate scale inhibition protocols" | The item names no wells, test dates or duration. Elsewhere the chapter describes Gladys McCall No. 1, in Cameron Parish, Louisiana, as tested for four years at an average of 20,000 barrels per day. For the chapter's statement about rates from reworked wells, see the Hulin well above. |
| 3 | "Brine, after gas extraction, could be successfully injected into shallower aquifers without affecting surface waters or subsurface fresh water aquifers" | A statement about the DOE test wells that names no wells, number of injection wells or time period. It concerns surface waters and fresh water aquifers only, and it is not a statement about future commercial-scale injection volumes. |
| 4 | "No observable subsidence or microseismic activity was induced by subsurface withdrawal and injection of brine, and no detrimental environmental effects attributed to well testing were observed" | It describes the DOE well testing program. It names no wells, monitoring networks, test volumes or monitoring period, and it concerns testing at program volumes, not large-scale production over decades. |
| 5 | "Corrosion, sanding and scaling could be controlled with chemical inhibitors and by reducing flow rates" | "Controlled" is the chapter's word. The item does not say which problem was handled by which method or at which well, and it does not say that no scaling, sanding or corrosion occurred. |
| 6 | "Demonstration that the production of gas from saturated brines under pressure was viable" | A statement from the DOE test wells. It gives no gas volume, flow rate or cost, and it is not an economic finding. |
| 7 | "A hybrid power generation system could be installed and operated." | The only hybrid power system described in the chapter's Gulf Coast section is the Pleasant Bayou No. 2 system in Brazoria County, Texas, which ran from October 1989 to the end of May 1990. The item says nothing about output, economics or duration. The chapter says that plant produced about 1 MW of power (see the test history above). |
The Pleasant Bayou plant, in the chapter's words
Two statements in the chapter's section on the plant (printed page 76) are quoted here. The first: "The hybrid power system demonstration at Pleasant Bayou was successful in all respects. Design power was achieved, and 3,445 MWh of electricity was sold to the local utility over the course of the test." It applies to this single demonstration plant of about 1 MW, not to geopressured power in general.
The second: "Successful operation of the hybrid cycle power plant clearly demonstrated that there were no technical obstacles to electricity generation from the Pleasant Bayou geopressured resource." The next sentence carries an exception: "Other than surmountable issues associated with scaling due to the high total dissolved solid content of the typical reservoir brines, a power plant could be built and operated with no technical or economic obstacles." That sentence names the Pleasant Bayou resource. The exception sentence names no place; it speaks of "the typical reservoir brines" and "a power plant". The chapter's economic study, in the limits below, reports costs above conventional sources at the time.
Source: Geothermal History, Reservoir Engineering, Section 3.0, DOE (2010): Section 3.7 on printed page 86, the plant statements on printed page 76. Read October 4, 2026.
Limits reported beside the findings
The chapter and other DOE-funded reports state limits. They follow the findings here so the two can be read together.
- Scale. A 1989 DOE overview says Pleasant Bayou No. 2 produced about 4 million barrels of brine, intermittently, from 1979 through 1983, but that testing was plagued by scaling of the production tubing, and that the testing phase under way in 1989 was aided by a downhole treatment in which scale inhibitor is pumped into the reservoir. The chapter says earlier tests at that well "led to problems with carbonate scale deposition in the production tubing and surface equipment, eventually resulting in failure of the well", and that substantial rework was required.
- Sand and disposal. The chapter says two of the most significant problems in production testing were the production of fine grained sand, sometimes in large slugs at high production rates, and an inability to sustain high brine injection rates in disposal wells. It says some problems "were serious enough to lead to the termination of testing in several wells either for physical and/or financial reasons".
- A projection. A 1990 DOE-sponsored paper says an earlier projection of 40,000 barrels per day for five years at Gladys McCall No. 1 "may be optimistic", because the rate for that well declined from 31,000 to 25,000 barrels per day during 1986. The paper's passage on this well continues after that sentence; the full passage is at the source link below.
- Economic selectivity. In the paragraph just before Section 3.7 the chapter discusses an INEL economic study of eight well cases and says: "However, this economically driven well/reservoir selectivity, which favors the more hot, more gaseous reservoirs, would significantly limit the number of economically viable geopressured-geothermal resources." Assuming the reservoir characteristics of the DOE design wells, the chapter reports that the cost to convert the energy to electricity was higher than costs from conventional sources at the time of the study and significantly greater than the DOE program goal. That is historical modeling, not a current cost or a forecast.
- A 1998 market judgment. A 1998 summary by Louisiana State University for DOE said that in the economic market of that day it might not be commercially profitable to exploit the resource, and that the rapid advance of technology could potentially make it attractive in the not too distant future. That is a 1998 judgment, not a current view.
Two more limits, on subsidence and on overlying reservoirs, follow.
Subsidence. In 1979 the Bureau of Economic Geology wrote that the potential for land subsidence from geopressured geothermal fluid production in the Texas Gulf Coast was unknown at that time, and that there was no large-scale water production from the geopressured zones. The 1998 summary says benchmark surveys around the design well sites observed no subsidence related to well testing. That is test-scale production only. The DOE chapter gives elevation changes of 4 to 10 millimeters per year at Gladys McCall, small but larger than the regional subsidence rate. It says researchers concluded the movement was probably not related to testing, since the drop came after testing stopped, and that there was no conclusive evidence that regional and local subsidence rates were altered by fluid withdrawal during well testing.
Overlying reservoirs. A Bureau of Economic Geology 1989 annual report, issued in 1990, says an evaluation of reservoir performance at active oil and gas fields in the immediate vicinity of the Pleasant Bayou fault block has not provided evidence of direct hydrologic communication between the geopressured aquifer and the overlying hydrocarbon reservoirs. It applies to that fault block only.
Sources: Geothermal History, Section 3.0, DOE (2010); Research Program Overview, DOE (1989); The Geopressured-Geothermal Resource, Research and Use, Idaho National Engineering Laboratory for DOE (1990); Summary Report Compilation, Volume I, LSU for DOE (1998); Environmental Overview, BEG (1979); 1989 Annual Report, BEG (1990). Read October 4, 2026.
What happened to the program
Pleasant Bayou
The DOE history chapter (2010) says of the Pleasant Bayou plant: "From October 1989 to the end of May 1990, the plant ran at or near design output, except for an occasional outage; the plant was shut down a month early because the brine injection well required rework." This is the chapter's wording about one plant of about 1 MW.
On printed page 76 the chapter also says: "Other than surmountable issues associated with scaling due to the high total dissolved solid content of the typical reservoir brines, a power plant could be built and operated with no technical or economic obstacles."
The chapter's closing sentences
The chapter closes its Gulf Coast section with: "At the time of the research program prevailing economic conditions limited continued production from geopressured-geothermal reservoirs. However, the program laid the foundation for all aspects of future development of this extensive resource." It names no specific economic condition. Just before that, in its economic study of eight well cases, it says: "However, this economically driven well/reservoir selectivity, which favors the more hot, more gaseous reservoirs, would significantly limit the number of economically viable geopressured-geothermal resources."
The budget
A 1998 summary by Louisiana State University for DOE says the program continued for seventeen years and that approximately two hundred million dollars were expended on research and well testing. The budget table in the chapter's Appendix A has a Geopressured-Geothermal column. Its figures are shown below as printed, with no adjustment.
Source: Geothermal History, Reservoir Engineering, Section 3.0, DOE (2010): the plant sentences on printed pages 75 and 76, the closing sentences on printed page 86. Read October 4, 2026.
| Fiscal year | Thousands of current-year dollars |
|---|---|
| 1976 | 1,182 |
| 1977 | 6,620 |
| 1978 | 17,100 |
| 1979 | 26,600 |
| 1980 | 35,700 |
| 1981 | 35,600 |
| 1982 | 16,686 |
| 1983 | 8,400 |
| 1984 | 5,000 |
| 1985 | 5,226 |
| 1986 | 4,426 |
| 1987 | 3,940 |
| 1988 | 4,955 |
| 1989 | 5,930 |
| 1990 | 5,523 |
| 1991 | 5,884 |
| 1992 | 4,916 |
| 1993 to 2006 | No entry. The cells are blank. |
| Total, as printed in the table | 193,688 |
The table gives blanks, not zeros, for 1993 to 2006. Appendix A says all funds are in current year dollars in thousands, with no adjustments for the time value of money. Fiscal year 1976 includes the transition quarter, when the federal fiscal year was advanced three months. In most cases the amounts are budgeted amounts shown as "Actual" in DOE's annual budget request to Congress, not necessarily the amounts appropriated.
Appendix A cautions the reader not to accept the amounts quoted in any single fiscal year as a fully accurate representation of the funds spent on a given technical area, and calls Geopressured-Geothermal a unique line item in the budget that could be easily tracked from year to year. It also says that over the whole period covered the totals are considered reasonably accurate. A second DOE-supplied funding table, the funding history table in the 1998 LSU summary Volume 2-A, is in millions of dollars, lists fiscal year 1993 as zero, totals 195.6 million dollars, and differs from Appendix A in several years, among them 1976, 1978 to 1981, 1985, 1989 (it includes 4.5 million dollars from the sale of Baca equipment) and 1990.
The table has entries through fiscal year 1992 and none after; the column goes from 35,600 in 1981 to 16,686 in 1982, down 53 percent, and to 8,400 in 1983, down 50 percent, about half each time, in thousands of current-year dollars.
Our view. Research budgets are set by people. In our view the injection well was not the whole story; politics was part of it.
Sources: Geothermal History, Reservoir Engineering, Appendix A, DOE (2010): the table on printed page 154, notes on printed pages 151 to 153; Summary Report Compilation, Volume 2-A, LSU Basin Research Institute for DOE (1998); Summary Report Compilation, Volume I, LSU for DOE (1998). Read October 4, 2026.
Recent activity
A 2013 DOE fact sheet describes co-produced resources as hot fluid that is a byproduct of oil, gas and other mineral extraction, used to generate electricity. In 2016 DOE published an article on a University of North Dakota project that generated geothermal power from hot water flowing naturally from petroleum wells in the Williston Basin. It concerns co-produced hot water in North Dakota, not a geopressured reservoir and not Texas. A DOE page on its GEODE initiative, which kicked off on September 10, 2024, says the oil and gas and geothermal industries have similarities that provide new opportunities, including co-production possibilities in existing oil and gas basins. A 2025 market report says DOE awarded funds in 2022 to four projects in its Wells of Opportunity initiative, to repurpose inactive or idle hydrocarbon wells for geothermal energy use, one of them in Texas. That initiative shares its name with the 1980s wells of opportunity above, and the report's passage on that initiative says nothing about geopressured reservoirs.
What this page does not say. It makes no resource, flow, temperature or feasibility claim for any place, and takes no engineering position. The numbers are history from named test wells, each with its source and date.
Our focus. We work on land and records for projects that use the existing DOE well, log and fairway records, and for new wells. The reports and record pages from the DOE program that sources list are on Where it is found.
Hot rock and engineered geothermal systems are a different case, covered at the sister site hotrock.land.
Sources: Co-Produced Resources Fact Sheet, DOE; First Permanent Facility, DOE; GEODE, DOE; 2025 Market Report, National Laboratory of the Rockies. Read October 4, 2026.