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A number of recent studies from the US shale sector are arguing that refracturing is a generally successful practice and that high oil prices make that even more true. New research from the Eagle Ford Shale in south Texas shows that refractured wells using liners can even outperform new wells benefiting from more modern completion designs. The developers of the liners and packers specially designed for refracs are also reporting increased interest for their technologies as the industry leans toward more sophisticated mechanical isolation techniques. In terms of the very lowest-hanging fruit, it is believed operators in North Dakota's Bakken Shale are sitting on some 400 openhole wells that if refractured would generate in excess of $2 billion--and that's at $60/bbl vs. this year's average oil price of almost $90/bbl. But despite the apparent progress and size of the prize, it does not appear that US shale producers are any closer to refracturing on a large scale than they were 5 years ago. Out of all the US horizontal well stimulations performed through September of this year, a little over 2% were refracs.
- North America > United States > Texas (1.00)
- North America > United States > North Dakota (0.88)
A number of recent studies from the US shale sector are arguing that refracturing is a generally successful practice and that high oil prices make that even more true. New research from the Eagle Ford Shale in south Texas shows that refractured wells using liners can even outperform new wells benefiting from more modern completion designs. The developers of the liners and packers specially designed for refracs are also reporting increased interest for their technologies as the industry leans toward more sophisticated mechanical isolation techniques. In terms of the very lowest-hanging fruit, it is believed operators in North Dakota’s Bakken Shale are sitting on some 400 openhole wells that if refractured would generate in excess of $2 billion—and that’s at $60/bbl vs. this year’s average oil price of almost $90/bbl. But despite the apparent progress and size of the prize, it does not appear that US shale producers are any closer to refracturing on a large scale than they were 5 years ago. Out of all the US horizontal well stimulations performed through September of this year, a little over 2% were refracs. The figure comes from Rystad Energy which identified in public data roughly 200 refractured wells out of the 8,900 total stimulations from January to September. Most of these refracs were in the Permian Basin spanning Texas and New Mexico and involved wells of a 2018 vintage or earlier. And most of the operators active in this space completed just between 1–4 refracs during the reporting period. The consultancy expects that as more data filters in, the count will be around 400 refracs by year’s end. That would likely be a little over 3% of total completions and roughly in line with last year’s final tally of 409 refracs. On a percentage basis, 2022 might also look similar to the 2018 peak of 570 refracs, or 3.3% of that year’s 17,000 completions. Justin Mayorga, a senior analyst of shale research for Rystad, said the data reflect that a healthy level of activity exists in the refrac space—but there’s little chance the 2018 record will be broken anytime soon. “It’s a very niche market,” he said. “The companies that are doing it are probably going to continue to do it, but I don’t think refracs are going to explode in numbers next year. I see stable activity that is very similar to this year’s 2–3% of total completions.” One reason refracs hold just a fraction of the overall completions market is because they’ve only been able to establish a limited business case in a sector that remains laser-focused on bringing in new wells. To this end, many operators active in refracturing describe how they use the technique not to boost production from older wells but more so to protect the outcomes on new child wells that share the same pad. But the biggest obstacle facing greater refrac activity in the US, according to Rystad and other analysts, is the lack of spare pumping horsepower.
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (4 more...)
Summary Hydraulically fractured shale wells typically exhibit high initial decline rate up to 90% in the first year of production. Refracturing (refrac) is considered as a method to potentially accelerate production and increase reserves. Field applications of refrac so far show mixed results, such that the business value of refracs has not yet been definitively established. A major contributor to poor refrac performance is selection of non-ideal refrac candidates. For example, wells with initially effective stimulation may not benefit from refracturing especially after extended duration of production and SRV depletion. In this work, a simple yet rigorous semi-analytical method is developed to identify wells with poor performance primarily due to understimulation. A procedure for refrac performance estimation is also presented which attempts to differentiate between reserves access and reserves acceleration and their effect of refrac performance. The method is based on a relative stimulation index (RSI method) developed from generalized flow equations. The RSI method is applied to a set of known refracs in the Haynesville shale to assess the refrac candidacy and performance of each well relative to actual field observations. The RSI method correctly assesses the refrac candidacy and performance of the well sets and demonstrates viability as a refrac appraisal tool. The RSI method also suggests that contacting new rock volumes (reserves access) may contribute up to 90+ % more to the overall refrac response compared to enhancing the permeability of previously stimulated rock volumes (reserves acceleration). Reserves access is therefore critical to the success of a refrac operation. Flow equations show that reserves access should reduce or maintain initial decline rate while reserves acceleration should increase decline rate. Field results suggest that when new rock volume is accessed, initial decline rate may be reduced by an average of 9%; The RSI method has been automated and applied to the oil and condensate window of the entire Eagle Ford shale play with 2,242 wells identified as potential refrac candidates.
- North America > United States > Texas (1.00)
- North America > United States > Montana > Sheridan County (0.24)
- Research Report > New Finding (0.48)
- Research Report > Experimental Study (0.34)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.83)
Abstract This paper presents a diagnostic-driven method of evaluating refracturing (refrac) techniques in unconventional wells. Detailed analysis across the lateral, using intervention based distributed fiber optic (DFO) measurements, allows for a comprehensive understanding of the refrac performance. While there are various approaches to refracing an unconventional well, there is a categorical division of two main strategies: iterations of limited interval re-stimulation or re-stimulate the entire lateral at once. Stage-by-stage refrac, via casing-in-casing or coil tubing with isolation-type packer tool, offers potential control over stimulation distribution but often incurs heavier cost compared to refracing the entire well simultaneously. The economically favorable simultaneous refrac of all stages (Bull head) can be executed at a lower price but at the cost of not knowing the extent of lateral distribution. With several possible approaches for refracing an entire lateral at once, further questions arise regarding which method provides the most laterally uniform re-stimulation and whether the resultant production improvement is from re-stimulated existing or newly created fractures. A major hurdle in both executing and evaluating the success of an all stage simultaneous refrac is the uncertainty of creating new fracture initiation points; furthermore, with complex heterogenic rock, different fracture designs, and different well completions, it is difficult to develop a comprehensive understanding of how well the refrac design worked. Diagnostic validation of the success of a refrac operation, as well as iterative improvements based on those learnings, is fundamental to determining a cost-effective strategy. A strong data set takes the guesswork out of refrac and is the best method for understanding how effective the refrac designs performed.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.41)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play > Shale Gas Play (0.41)
- Geology > Geological Subdiscipline (0.34)
Impact of Re-Fracturing Techniques on Reserves: A Barnett Shale Example
Brady, Jared (Devon Energy Corporation) | Daal, Johan A. (Devon Energy Corporation) | Marsh, Kevan (Devon Energy Corporation) | Stokes, Trevor (Devon Energy Corporation) | Vajjha, Pavan (Devon Energy Corporation) | Werline, Rusty (Devon Energy Corporation) | Williams, Chris (Devon Energy Corporation)
Abstract During a low commodity price environment operators look for ways to increase production with very little capital. One of the approaches includes re-stimulating or re-fracturing an already producing well to improve its production and value. Re-fracturing horizontal wells in unconventional formations is still in its infancy. There is lack of consensus regarding techniques used for candidate selection and execution, and results have been enigmatic at best. Some of the most common concerns include zonal isolation, diversion agents, costs, field execution and financial returns. The Barnett Shale in Texas played a key role in unlocking vast amounts of hydrocarbons around the world. This basin is already considered mature, and re-fracs have already been attempted in vertical and horizontal wells of different vintages. This effort focuses on the Barnett Shale, and shows the effect that restimulation has on reserves. Field examples are used to illustrate the benefits and risks involved in these operations. This paper will discuss an integrated approach to candidate selection, re-completion methodologies, and an interpretation of results by understanding the rate-transient response of the well. Introduction The Barnett Shale formation is located in the Fort Worth Basin of north-central Texas (Figure 1) and has been developed as a horizontal play since the early 2000's. In Devon's core area, the Barnett formation averages 60 feet of Upper Barnett shale and over 275 feet of Lower Barnett shale which is separated by the Forestburg Lime. A type log is shown in Figure 2. The Barnett shale averages 5 – 6% porosity with a 25% water saturation is slightly over-pressured. Devon Energy operates 5,000 Barnett Shale producers, with over 3,000 horizontals and nearly 2,000 vertical completions. Since the early 2000's Devon Energy has been evolving re-fracturing techniques in the Barnett to slow the decline in base production through various methods.
- North America > United States > Texas > Tarrant County > Fort Worth (0.24)
- North America > United States > Montana > Sheridan County (0.24)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play > Shale Gas Play (1.00)