Thermal Fluid for Prevention of Fluid Losses in Oil and Gas Well Construction ("Texas Heat Wave")
Physical Sciences : Petroleum
Available for licensing
- Eric van Oort , Petroleum and Geosystems Engineering
- Besmir Hoxha , PGE
- Ali Karimi Vajargah , PGE
- Robert Williams III, Ph.D. , College of Pharmacy
- Hugh Smyth , College of Pharmacy
- Silvia Ferrati, Ph.D. , College of Pharmacy
Loss of well fluids is a profound problem in oil and gas well drilling, particularly when drilling more complex wells such as ultra-deepwater wells. High fluid losses occur when the fluid pressure in the wellbore is enough either to open preexisting fractures in the drilled formations or to open new fractures. Exceedance of a well’s fracture gradient is determined by the rock stresses in the formation and rock tensile strength. This "lost circulation" problem is extremely costly in that such wells cannot be drilled without incurring heavy mud losses while either drilling, cementing, or completing the well. The mud losses lead to inefficient time usage, cost overruns, and issues jeopardizing competent well construction.
A multitude of conventional lost circulation treatments exist, although none have effectively used near-wellbore heating. Previous attempts to heat the wellbore through mechanical and chemical means were unsuccessful. Although treatments for mud losses exist, the implementation of a heating treatment may prove to be more efficient and productive than current methods.
Researchers at The University of Texas at Austin have designed a controlled release system of thermally active substances for thermal conductivity and expansion of near-wellbore rock formations. The utilized exothermic reaction is capable of generating heat in the wellbore about two to five hours post-injection. The fracture gradient of a well is sensitive to the temperature of the well fluid. Lower fluid temperatures decrease the formation temperature, allowing for easier fracturing of the wellbore and larger mud losses. In contrast, fluid temperatures that are higher than the formation temperature increase the thermal component of the rock stresses and the value of the fracture gradient. The result is increased difficulty in fracturing the wellbore and prevention of mud losses.
There are currently no technologies that actively exploit the generation of heat for fluid loss prevention purposes. The use of an exothermic reaction to heat the wellbore fluid and nearby rock formations in conjunction with a delayed release mechanism allows for maximum impact of the heating process to the rock formation. Both aspects of the proposed heating method are entirely novel and can potentially reduce mud losses by significant amounts.
- Prevents/eliminates fluid losses, such as drilling, cementing, and completion fluids
- Applicable to wells with narrow drilling margins
- Prevention of poor zonal isolation
- Increased well efficiency and productivity
- Reduces well production costs
- Novel elements for near-wellbore and fluid heating
- Exothermal reaction to heat wellbore fluid and formation
- Delayed release mechanism that allows for the exothermal reaction to be delivered to the formation at maximum impact
The lost circulation problem is costly because of the loss of expensive fluids and cost associated with the amount of rig time needed to deal with the problem. This non-productive time (NPT) can range from $1MM/day to $1.5MM/day on an offshore drilling platform and can also have significant costs on less expensive well operations. It is estimated that the lost circulation problem causes several billions of dollars of NPT annually for oil and gas well operators, particularly those that manage deepwater wells. The implementation of the proposed wellbore fluid heating method can potentially lower operating costs and enable deepwater drilling to become more commercially viable in the growing oil market.
Proof of concept
- 1 U.S. patent application filed