The price of oil dropped in 2015 and many oil and gas workers were laid off. But soon after, 2018 was called the year of the frac because the industry boomed again, led by the mighty Permian basin with its prolific oil and gas resource. Then the pandemic of 2020 hit, OPEC squabbled with Russia, and the oil price fell again – all the way to zero, unbelievably. Now in early 2021 it’s picked up to $60/barrel.
Against this turmoil, many oilfield jobs have been lost, perhaps permanently. But tech-savvy consultants have appeared on the scene, parlaying all sorts of new ideas and processes to improve fracking operations.
Looking backwards, such improvements seemed to come slowly, but regularly, until 2014 when I retired from the industry after 30 years involved with fracking. But now in 2021 the changes that have appeared are remarkable. The number of start-up companies feels an order of magnitude greater than in 2014 and their particular expertise is deep and impressive.
The complexity of fracking in shale.
Why is this surge of activity happening now? The main reason is that fracking in shales is complicated. It’s worth taking a little time to appreciate this. Figure 1 shows four separate fracking operations in a horizontal well. But nowadays there can be up to 40 fracking operations in each horizontal well. The water used is typically 20 million gallons – enough to fill a football stadium to a height of 40 feet if confined to the grassed area.
Proppant-sand, which is pumped with the frac water and used to prop the created fractures open, would fill 93 railroad containers. All this in just one well!
The sequence of fracking operations creates its own reservoir around the horizontal well. That’s because shale rock is very tight, essentially impermeable to flow, until you crack the rock up by the fracking process. The result is a network of tiny fractures as illustrated by Figure 2.
One of the key issues has been how to characterize the fractures in this network – their length, spacing, and opening widths. The goal was always to create the largest spread of fractures that will stay open after the big motors stop pumping the fracs, because this will enable the highest flowrate of oil or gas to the horizontal well and then to the surface.
If there is a paucity of fractures created at some position along the horizontal well, it would be said that this particular frac stage is under-stimulated. This is a common occurrence.
New initiatives related to fracking.
A recent report has made a thorough listing of new initiatives, and like all new ventures, maybe only a fraction will survive. But their accomplishments to this point are impressive. Just a few of them are summarized here to provide a taste of the banquet of fracking diagnoses and analyses.
Three innovations are striking: One, using acoustic waves (sound sources) to probe the network of fractures in Figure 2. Two, use of AI and machine learning to improve fracking stimulation at a detailed level. Three, alternative fracking pumps that will reduce the amount of diesel burned and lower GHG emissions.
Seismos-MWF (Measurements While Fracturing) measures and detects fracture systems created by each fracking operation. This is done by sending an acoustic signal down the well to diagnose the complex fracture during a fracture operation, then back to the surface.
If a frac stage is under-stimulated, an AI (artificial intelligence) program in real time alerts the operator to tweak the frac parameters like rate or volume or fluid type to correct the issue.
The report claims that the instrument has improved well production by 8 boe (barrels of oil-equivalent) per horizontal foot. For a two-mile long well this amounts to almost 85,000 barrels in a six-month period.
Under-stimulation can be caused by in-situ stress change along a well, a geological hiccup, or influence of a nearby well that has been fracked (called a frac hit).
TGT’s Fracture Flow measures the sound sources created by frac fluid movement in the fractures. It can diagnose fracture density, and even determine fluid movement to or from the fracture network.
One result, in the form of a well log, revealed 22 fractures at the wellbore but only five were opposite flow ports. The other 17 were misaligned with the flow ports, which is a bit surprising. On average, there were three active fractures per stage.
Well Data Labs AI-powered platform. During drilling and fracking, when wellbore pressures are monitored, an operator can make decisions based on AI, such as multivariate analysis. Machine learning can in real time provide proactive corrections such as when pressure rises fast due to an impending screen-out.
Zeeospheres Ceramics LLC’s Deeprop 1000 is a hard, strong, perfectly round micro-proppant that is ten times smaller than the smallest proppant-sand, 100-mesh, that is regularly used along with 40-70 proppant-sand in shale oil or shale gas fracking operations.
This new micro-proppant can pass into and prop open fractures much smaller than previously possible (Figure 4), and thereby increase their contribution to gas or oil flowrate. Operators have demonstrated the upside in basins such as the Delaware in the Permian.
Greenhouse gas emissions.
Many oil and gas companies have an ESG or sustainability department, and what some term the social contract. One growing concern is about greenhouse gas (GHG) emissions and global warming. Some upstream companies are trying to decrease their carbon footprint by reducing the amount of diesel fuel during drilling or fracking operations. To illustrate, Figure 4 shows twenty separate frac pumping trucks lined up in two rows of ten ready to go on a shale well.
Siemens Energy, Electric and Mechanical Solutions have gas turbine generators mounted in an over-long semi-trailer that are used to power electrical fracking pumps. They can reduce pumping fuel costs up to 80%. The units also reduce GHG emissions because natural gas exhaust is cleaner than diesel.
Rolls-Royce’s MTU Hybrid E-Frac Power System uses natural gas, possibly produced nearby, to generate electricity that is stored in batteries then used to pump the frac operations in a hybrid system. Gas burns cleaner than diesel so the greenhouse gas (GHG) emissions are up to 80% lower. Also, pumping power costs are reduced by up to 58%.
This is just a sampling of innovations appearing on the oil and gas scene. My favorite is the Deeprop 1000 ultra-small proppant that can get into the tiniest fractures in Figure 3 to keep them open (my last research project led to recommending proppant-sand that was smaller than 100-mesh, but I couldn’t sell the concept.)
It’s great to see tech-savvy folks pushing established oil and gas companies to adopt advanced technology.