Oil & Natural Gas Projects
Exploration and Production Technologies
Production Improvement from Increased Permeability Using Engineered Biochemical
Secondary Recovery Methodology in Marginal Wells of the East Texas Field
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.
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.
TENECO Energy, LLC
Wheat Ridge, CO
San Antonio, TX
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
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:
- Increase oil production.
- Reduce operating expenses.
- Eliminate dangers associated with manufacture, transportation and handling
of and worker exposure to hazardous chemicals.
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.
For Task 1, researchers:
- Added the engineered biochemical solution to the well by gravity feed down
the annulus. For the initial well clean-up phase, the solution was mixed at
the wellsite. The biochemical solution was allowed to acclimate and react for
24-72 hours, and then the well was placed on production.
- Treated three wells with known wellbore characteristics and perforation depths,
and all three wells evidenced an improvement by either increased production
volume or the pumping of sand, scale, and other debris with the produced water.
- Found that operations are affected at least two ways by the mobilized debris:
1) interference with pump action that requires pump removal and redressing,
or 2) the removal of scale and paraffin exposes corrosion holes that were protected
by the coatings of scale and paraffin.
- Learned that the use of cup-type tubing pumps significantly improves the capability
of the pump to lift and discharge the mobilized debris with the produced fluid.
The identification of weak or damaged tubing simply allows for proactive maintenance
For Task 2, project performers:
- Selected two wells for the more-substantial biochemical treatment.. The treatment
consists of at least 25 gallons of the biochemical solution, 25 gallons of nutrient
solution, and about 140 barrels of carrier 2% KCl water.
- Transported the biochemical solution in drums and added it directly to the
annulus of the well; and the 2% KCl solution was brought in by truck to the
wellsite. Addition of the solution is rapid, and the only time constraint is
the delivery time for trucking. Wells were left shut-in for 7-10 days for the
microbes to acclimate and react. Wells were then placed back on production.
- Discovered that Well No. 9 was improved, with oil production increased from
about 0.3 barrels of oil per day (BOPD) to 1.5-2.5 BOPD. Water production increased
only slightly, indicating that the treatment could be improving the oil-wet
permeability more than the water-wet permeability.
- Also successfully treated Well No. 8, as evidenced by the increase in gas
pressure and the increase in oil percent. This well did not produce a total
fluid volume that was sufficient to remove the mobilized material.
- Learned significant lessons that will benefit other operators in the future.
The quantity of material that was mobilized is significant. Flow lines, separators,
and valves all became clogged with debris, and pressure-actuated valves failed.
A three-phase separator is not recommended; rather, a large gunbarrel works
far more effectively in separation of oil and water in the presence of the mobilized
sediment and debris. By using a cup-type tubing pump and gunbarrel, the movement
of debris ceases to be a problem.
Researchers in Task 3:
- Selected the No. 1 well for the insertion of the biochemical treatment as
much as 20 feet into the producing reservoir to treat the high molecular weight
hydrocarbons. Fluids were not pressure-injected because of the age of these
wells and uncertainty of well integrity when pressurized. The wellbore first
was spotted with 25 gallons of the biochemical solution and 25 gallons of nutrient
solution, and then the well was filled with a 2% KCl water carrier solution.
The fluid level of this well was low, and thus the hydraulic head was able to
force the reacting solution at least 20 feet into the selected portions of the
- Shut in the well for 7 days, allowing the solution to react and acclimate.
Production then was initiated at 150 barrels of fluids per day, and chloride,
oil, and water were monitored for two weeks. The biochemical solution was withdrawn
within 48 hours, and the production was restored to essentially the same pretreatment
levels. It is concluded that the permeability-blocking material within the reservoir
either is not easily accessed or not significantly affecting production.
- Observed that the most significant production improvements occurred when the
immediate wellbore area is treated. The effects of deeper reservoir treatment
are not significant, based on this limited testing.
- Reported that this procedure is now being used by other operators on nearby
leases with notable success and with wells that are less deviated and have fewer
mechanical complications. The long-term success should be significant.
Current Status (October 2005)
This research project has been completed. The procedures are currently being
used successfully by other operators on nearby leases in cooperation with
Finney No. 9 location in East Texas Field, Rusk County, TX.
Semi-annual and final reports to DOE.
Project Start: June 1, 2002
Project End: September 30, 2006
DOE Contribution: $900,000
Performer Contribution: $1,011,710 (53% of total)
NETL - Dan Ferguson (firstname.lastname@example.org or 918-699-2047)
TENECO - R.L. Bassett (email@example.com or 303-423-8187)
MICRO-TES - William Botto (firstname.lastname@example.org or 210-558-4757)