Project objectives include 1) the testing and evaluation of a method for increasing oil production by implementing innovative technology using a multidimensional biochemical secondary recovery treatment engineered to remove permeability impediments, e.g., paraffin, asphaltene, inorganic scale, and iron corrosion and to mobilize residual frac gels, etc., accumulated over the 70-year production history of East Texas field; and 2) devising a protocol that has the significant environmental advancement that no petroleum-based solvents or additives are required-consequently, permits, remediation, and spill clean-up are avoided.
This project was selected in response to DOE's Oil Exploration and Production solicitation DE-PS26-02NT15377 (March 15, 2002). The objectives of this solicitation were to allow small, independent companies to test high-risk technologies that can lower operating costs and extend the life of aging and declining U.S. oilfields.
TENECO Energy, LLC
Wheat Ridge, CO
San Antonio, TX
East Texas field is a "giant" oilfield discovered in the 1930s, with about 35,000 wells drilled to date. The field, comprising over 140,000 acres, is a classic stratigraphic trap with active water and solution gas drive. Production is primarily oil, with over 5 billion barrels produced to date. Overproduction and overdrilling (units of less than 4 acres) have plagued this field from its inception. Because of this overproduction and overdrilling, the reservoir pressure and temperature have dropped abnormally fast, resulting in precipitation of paraffin and asphaltene in the pore throats of the producing formation. This precipitation has resulted in reservoir plugging and greatly decreased total recovery for the reservoir. In addition, this overproduction caused water coning, resulting in emulsion blocks and inorganic solids being pulled into the oil leg of the formation. Frac gels and formation damage from numerous types of stimulation treatments also have damaged reservoir permeability. By using regenerating biochemicals and organic surfactants, it was deemed possible to restore permeability, resolubilize the paraffin and asphaltenes, break the emulsions, and dissolve the inorganic solids into the water phase. Additionally, the surface tension of the oil to the rock grain could be reduced, allowing more oil to be mobilized. Biochemical alteration of the oil lowers the cloud point of the oil and raises its gravity. This type of treatment should prove very cost-effective and environmentally friendly for the small, independent operators that dominate East Texas field. They can introduce the biochemical product into the reservoir through squeezes and soaks in the producing wells and by direct injection with saltwater as the carrier. The overall result of these processes and treatments should yield much greater recoverable reserves.
A combination of a regenerating biochemical mixture and an organic surfactant was applied to wells in East Texas field with the goal of restoring permeability, reversing formation damage, mobilizing hydrocarbons, and ultimately increasing production. Initial work was designed to open the perforations and remove blockages of scale, asphaltene, and other corrosion debris. This was accomplished on three wells that produce from the Woodbine formation and was necessary to prepare the wells for more-substantial future treatments.
Two wells were treated with much larger quantities-25 gallons-of the biochemical mixture with a 2% KCl carrier solution that carried the active biochemical solution into the near-wellbore area adjacent the producing reservoir. After a 7-10 day acclimation and reaction period, the wells were put back on production. The biochemical solution successfully broke down the scale, paraffin, and other binders blocking permeability and released significant debris, which was immediately produced into the flow lines and separators. Oil production was clearly improved, and the removed debris was a maintenance issue until the surface equipment could be modified.
The permeability restrictions in a cylindrical area of 10-20 feet from the wellbore within the reservoir were treated with the biochemical solution. Fluid was forced into the producing horizon using the hydraulic head of the well filled with 2% KCl solution, allowed to acclimate, and then withdrawn by pumping. The chloride content of the produced water was measured, and production of oil and water was monitored. The most significant effect in improving permeability and removing scale and high molecular weight hydrocarbons was accomplished in the wellbore perforations and near-wellbore treatments performed earlier in the project. Deeper insertion of the solution had a minimal impact on production. .
The methods developed and used in this project can be used to:
For Task 1, researchers:
For Task 2, project performers:
Researchers in Task 3:
This research project has been completed. The procedures are currently being used successfully by other operators on nearby leases in cooperation with Micro-Tes, Inc.
Semi-annual and final reports to DOE.
$1,011,710 (53% of total)