Finding oil and gas is one thing. Pulling it out of the ground is another. Each process is technologically complex.
According to a statement released and published by Saudi Aramco on Rigzone, for extraction, production engineers often inject chemicals into wells to create or keep open pores in rock so that oil and gas can flow to the surface.
Formulating the right mixture of chemicals is crucial, and comes with a series of daunting constraints.
Most importantly, the solution must enhance the transit of gas through a reservoir to help production, while at the same time interacting safely with the bedrock of the reservoir so as not to damage it. The solution must also be able to withstand scalding hot temperatures of more than 200 degrees Fahrenheit, not corrode metal pipes used to feed wells and, ideally, react slowly over time so that operators can keep costs down by limiting how often they need to put fresh chemicals in wells.
The challenge is that much greater when dealing with some of the largest wells in the world.
Acidizing has long been one method of well stimulation available to producers. In the early days of well acidizing, reaction rates were too fast. Later, the industry turned to acid-in-oil emulsions to slow down reaction rates but saw viscosity and friction pressures rise as a result, in addition to cumbersome mixing procedures.
Now, Aramco researchers have developed a hybrid acid system for stimulation of carbonate reservoirs that is both slow-reacting and exhibits low viscosity. They did this not by adding more chemicals to get these attractive features, but by taking away a key ingredient: water, thus eliminating the need for polymer addition or emulsification processes.
Importantly, the solution causes relatively little corrosion on pipes and field operators can easily mix it in the field.
In tests, the researchers have successfully achieved a viscosity close to that of water, which is relatively low. Water, for example, has a viscosity rating of around 1 centipoise. They also have found the hybrid acid system dissolves carbonate rock well, so that it can clear out paths in rock. Moreover, they have slowed down reaction kinetics, by reducing the amount of water, giving the solution more time to propagate further.
The new system is showing promise, with improvements in performance compared to conventional emulsified acids.
This research project is just one example of how working at Saudi Aramco is full of challenges and opportunities. It is a company where you can put your talent to work, explore the world, make a difference and solve complex problems.