Blog

What ‘company culture’ means to us

We recently held our annual company retreat. This is an important event because we are a fully remote company, and it gives us the chance to get together in-person and spend quality time. This year, we did the retreat in Houston, following URTeC and our annual symposium. We visited Space Center Houston, went to an Astros game, and ate BBQ and Tex-Mex. As a Houston native, I picked some of my favorite things to do in town! We also held a meeting on ‘company culture.’ I asked the group – how do you perceive our company culture? What do we do well, and what could we do better? Here are the highlights.

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Horizontal hydraulic fractures in shales: are they real?

In ResFrac, we are always challenging ourselves—what should we be doing better? What new capabilities should we add to the simulator? One of our newest projects is adding horizontal fracture propagation. Under most conditions, hydraulic fractures form vertically, not laterally. However, in specific circumstances, horizontal fractures develop. Sometimes, they form in addition to vertical fractures, and sometimes, they form exclusively without any vertical fractures. Horizontal fracture propagation has not conventionally been included in commercial hydraulic fracturing simulators, but we think this is a capability well-worth developing.

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Previewing the Seven(!) ResFrac Papers to be Presented at the Unconventional Resources Technology Conference

Next week, ResFrac will be coauthoring seven papers at the Unconventional Resources Technology Conference (URTeC). These papers include: operator case studies in the Haynesville, Marcellus, and Bakken, a study quantifying the effect of proppant uniformity on production and economics, a new procedure generalizing the Devon Quantification of Interference (DQI) method, and an excellent paper by a University of Texas PhD student on proppant flowback.

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Welcoming Dr. Thomas Finkbeiner to the team as a Senior Technical Advisor

ResFrac is honored to welcome Dr. Thomas Finkbeiner to the team as a Senior Technical Advisor. Having lived many years in the region and consulted with Saudi Aramco and others, Thomas brings valuable technical and regional expertise to the ResFrac team. We look forward to his contribution as we develop and penetrate the rapidly growing Middle East market.

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Notable papers from the 2024 SPE Hydraulic Fracturing Technology Conference

Last week wrapped another outstanding SPE Hydraulic Fracturing Technology Conference. Every year, I write a blog post highlighting notable HFTC papers. Here is this year’s edition! As in past years, this is not an attempt to pick the ‘best’ papers. It’s a selection of papers that I personally found insightful, based on my own interests and specialization.

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Recent Recorded Talks on EGS and DFIT

Below are links to watch two recently recorded talks. The first was a presentation with ThinkGeoEnergy discussing the impressive results from Fervo Energy’s recent Project Red pilot. The second was a presentation with whitson summarizing the URTeC-2019-123 compliance method procedure for interpreting DFITs. If you are interested in either topic, please check them out!

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Fervo Energy’s ‘Project Red’ Results Are a Historic Breakthrough for Geothermal Energy – What Comes Next?

Fervo Energy announced the results from their ‘Project Red’ pilot in northern Nevada (Norbeck and Latimer, 2023; Ma, 2023). The results are spectacular. For nearly 50 years, the goal of Enhanced Geothermal Systems (aka, Hot Dry Rock) has been to convert low permeability, hot formations into economically viable geothermal reservoirs (Murphy et al., 1977). Success has been elusive. During stimulation, flow tends to localize into a small number of flowing fracture pathways. This limits the flow capacity and heat sweep efficiency of the resulting reservoir.

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ResFrac at the Comrades Marathon in South Africa (an Ultramarathon)

Comrades Marathon is the world’s largest and oldest ultramarathon.  The first race was in 1921. The number of registrants for this year was capped at 20k.  The marathon runs from the city of Durban to Pietermaritzburg (“up” run) or in the other direction (“down” run). The “down” run is a little bit longer at around 90 km, while the  “up” run is 87 km. This year we did the “down” run, but it was shortened to 87.7 km or  54.5 miles. “15 minutes less of pleasure” – as one of my friends said. 

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Impact of well orientation on well productivity

Hydraulic fractures tend to propagate in a plane that is perpendicular to the least principal stress, as noted by Hubbert and Willis in 1957. As a result, unconventional oil and gas wells are typically drilled in the direction of Shmin to maximize drainage area. However, in some regions, due to acreage constrains by operators, wells are drilled in different directions, regardless of the stress orientation to maximize acreage production by maximizing the number of wells per acreage.

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Recorded ARMA HFC 2023 Series Presentation– Optimization of Perforation Phasing for Improving Uniformity of Proppant Distribution Between Clusters

This ARMA Hydraulic Fracturing Community (HFC) presentation summarizes the work on proppant transport in horizontal perforated wellbores. Specifically, it discusses the model for proppant distribution between perforations depending on their orientation and location within the stage, optimal configurations are proposed, and performance is evaluated.

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Cyclists at top of Breckinridge Mountain

ResFrac at the Breckenridge Imperial Challenge

It’s that time of year again for our ResFrac team to embark upon the Imperial Challenge in Breckenridge, CO! As with last year, Egor, Dirk (ResFrac investor), and Garrett tackled the challenge this year. The Imperial Challenge is an annual triathlon where racers bike or run from the town of Breckenridge 6 miles and 850 feet up to the base of the Breckenridge ski resort, then skin (ski uphill) 3000 ft to the peak of the resort at 12,998 ft, then… ski off the other side.

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Technical barriers for deep closed-loop geothermal

This is the most exciting time in my lifetime for geothermal. There are many, many innovative things happening. To name a few – promising new approaches to Enhanced Geothermal Systems, geothermal projects in sedimentary and lower enthalpy formations, new approaches for geothermal exploration, lithium extraction from produced brines, geothermal energy storage, integrations with CO2 storage and capture, and new technologies for producing energy from hot water that is coproduced with oil and gas. However, this post is about a concept about which I remain skeptical – deep closed-loop heat exchangers (McClure, 2021). These designs are sometimes called ‘Advanced Geothermal Systems,’ AGS (Malek et al., 2022).

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Modeling simulfracs and subsurface implications

Simulfrac’s are growing in popularity (see 2021 JPT article for when the trend was just gaining momentum). The idea is that one pumping crew can treat two wells simultaneously versus one well at a time. As such, a frac crew may zipper four wells at a time versus two. At ResFrac we are seeing an increase in simulfrac interest across our consulting and license customers. Simulfrac’ing wells within the ResFrac software is simple to set up without any complicated modifications – so this makes ResFrac an ideal platform to investigate the effects of simulfracs.

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Optimization of perforation orientation for achieving uniform proppant distribution between clusters

Previously, a mathematical model for the problem of slurry flow in a perforated wellbore was described and the underlying physical mechanisms were discussed. The purpose of this blog post, on the other hand, is to couple the model with an optimization algorithm to investigate optimal perforation orientations that lead to the desired uniform proppant distribution between perforations. A brief description of the model is added at the beginning to cater for readers who are not familiar with the previous blog post.

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Interesting papers from the 2023 SPE Hydraulic Fracturing Technology Conference

The 2023 SPE Hydraulic Fracturing Technology Conference was last week, and as usual, it had an outstanding lineup of papers and speakers. This blog post has a brief lineup of some of the papers that I found most interesting. As in past years, this rundown focuses on papers that I found interesting, based on my own personal interests. Usually, I am most interested in papers that improve our understanding ‘what’s going on’ in the subsurface. Also, I coauthored a paper at the conference, so naturally, I can’t help but include it on this list!

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Proppant distribution between perforation clusters

This blog post summarizes the model for calculating proppant distribution between perforation clusters. A very detailed description of the model and literature review are available in [1]. The purpose here is to outline the model and its main features, to demonstrate the comparison with some of the available data (more comparisons in [1]), as well as to discuss limiting cases and sensitivities to various parameters. This blog post is solely focused on presenting the mathematical model. In future work, the results will be applied to practical optimization decisions.

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Figure 5: Example simulation with ‘submesh fractal D’ set to 0.6.

Simulating ‘Fractal Fracture Swarms’ in a General-Purpose Reservoir Simulator

This blog post describes a new capability in ResFrac to capture the effect of ‘fracture swarms’ on production decline trends. Based on work from Acuna (2020), the idea is that variable spacing between fractures causes a gradual onset of production interference. Fractures in a swarm may be numerous and tightly spaced,  so rather than representing each individual crack in the model, we treat each swarm as a single crack and use a numerical technique to capture their effects. In ResFrac, this capability is useful because it provides another mechanism for explaining (and matching) production drawdown trends. For further details, refer to Section 19.10 from McClure et al. (2022).

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How to Diagnose False Radial Flow in a Diagnostic Fracture Injection Test (DFIT)

Genuine radial flow is rare in shale DFITs. If it does occur, it is typically observed in tests with very low injection volume (less than 10-20 bbl), unusually long shut-in (longer than one week), and relatively high permeability (greater than one microdarcy). Genuine radial flow should only be diagnosed if it occurs after an extended (at least one log cycle) period of after-closure linear flow. If ‘false radial’ flow is misdiagnosed and used to estimate permeability, it leads to a large overestimate (10-100x).

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2022 Geothermal Rising

Reflections from the 2022 Geothermal Rising Conference

This is an exciting time for EGS. Multistage hydraulic fracturing has tremendous potential to improve the productivity of geothermal wells in low permeability formations. Projects are happening right now to test this concept in full-scale EGS wells. If they prove successful, we could soon see a major increase in geothermal energy production.

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Automated history matching to fracture geometries as measured by Volume to First Response (VFR): A Tutorial

In this post, I will walk through a simple example of using SWPM to calibrate the fracture geometries of a hypothetical data set leveraging the ResFrac Automated History Matching functionality to expedite the workflow. In a follow-on post, I use the model to demonstrate some intuitions on fracture geometry using the Sensitivity Analysis functionality as well as some nuances of VFR calibration.

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Highlights on propagation from preexisting fractures in ResFrac

The purpose of this blog post is to cover recently developed ResFrac capability that allows investigation of the effect of natural fractures on hydraulic fracture propagation. While this option has always been available for the ‘discrete’ propagation algorithm, now it also has become available for the ‘continuous’ algorithm. There are some noticeable changes compared to the previous implementation and they are covered next.

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simulation with five wells in a hypothetical formation with two pay zones. In the base simulation, all the wells are landed in the upper pay zone. However, the algorithm is given the option to vary the landing depth of the second and fourth wells. The figures below show the ‘baseline’ simulation.

ResFrac’s Automated Economic Optimization Tool

ResFrac’s automated optimization tool allows you to quickly and easily identify the economically best well spacing and frac design. This blog post steps through a simple demo of our built-in economics engine that is similar to those used by commercial software in the industry. It accounts for details such as working interest, different types of taxes, time-varying operations cost, etc.

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2022 ResFrac Annual Symposium

Last week we held our Fourth Annual ResFrac Symposium. The premise of the event is to bring together ResFrac users to share use cases, best practices, and general developments in the industry. This year was our biggest yet, with nearly 100 people joining either in-person or online throughout the day-long event, representing 26 different oil, gas, and geothermal operating companies, seven universities, and several service company collaborators.

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ResFrac Retreat in Colorado

For the first time in more than two years, the entire (almost!) ResFrac team gathered in Denver. We mixed education (thank you to our friends at Liberty Services for showing us the nuts and bolts of frac’ing)…… with fun.

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Commentary on Four New DFIT Papers: (a) Direct In-Situ Measurements of Fracture Opening/Closing from the EGS Collab Project; (b) Comparison of Stress Measurement Techniques from the Bedretto Project; (c) a Statistical Summary of 62 DFITs Interpretations Across Nine Shale Plays; and (d) A Different Perspective: An Article Advocating the Use of the Tangent Method

This post provides commentary on recent four papers on diagnostic fracture injection testing (DFIT). The first paper uses in-situ deformation measurements to directly observe fractures opening and closing during fracture injection-falloff tests (Guglielmi et al., 2022). The second compares various stress measurement techniques in a series of fracture/injection tests from the Bedretto project (Bröker and Ma, 2022). The third statistically reviews results from applying the interpretation procedure from McClure et al. (2019) to 62 DFITs across nine different shale plays (McClure et al., 2022). The fourth is an op-ed written in JPT (Journal of Petroleum Technology) by an advocate of the tangent method for estimating DFIT closure stress (Buijs, 2021; 2022). This article presupposes that the reader already has familiarity with these topics. If you would like more background, please refer to McClure et al. (2019).

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Notable Papers from SPE HFTC 2022

The SPE Hydraulic Fracturing Technology Conference (HFTC) was last week. There were tons of great, practically relevant, papers. People are really locked-in on the key value drivers. This blog post gives a sampling of a few of the papers that I found most interesting. I don’t discuss any of the ResFrac papers because they were in a previous blog post.

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Four ResFrac papers at HFTC 2022!

We at ResFrac are coauthoring four papers at HFTC. The papers describe a parent/child case study performed with Devon in the SCOOP/STACK, our new automated history matching and economic optimization tools, a new crack propagation algorithm designed to improve numerical accuracy and handling of thin layers, and a modeling study on application of multistage hydraulic fracturing for geothermal energy extraction.

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Understanding fracture morphology

Field scale hydraulic fracture simulations reveal a variety of complex fracture geometries. Very often stress interaction between the fractures leads to very asymmetric fracture growth within a stage. At the same time, for some other cases, all the fractures are more regularly shaped and symmetric. This blog post presents results of numerical simulations and analysis demonstrating how fracture morphology changes versus problem parameters for some fundamental cases. The results can be used to better understand the observed fracture complexity in a field scale simulation or as a guideline to achieve the desired fracture morphology.

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Cyclists pose for photo

ResFrac Endurance Team takes on The Triple Bypass

Three brave ResFrac riders took on the Triple Bypass rider in Colorado on August 21. The Triple Bypass is a famous Colorado ride stretching 110 miles and climbing 11,000 ft between Evergreen, CO and Vail, CO.  Egor Donstov, Janz Rondon, and Garrett Fowler rode this year, sporting ResFrac jerseys and lively Mongoose tattoos. While Egor and Garrett enjoyed the views, Janz powered up the climbs, finishing in eighth in a field of over 500 riders in the 40+ category.

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ResFrac user meeting

Last month we held our third annual ResFrac Symposium, where users presented case studies and panel discussions on industry topics. This year’s lineup featured six operator-speakers as well as guests from the DOE and an independent consultant. We had several talks centered around core workflows enabled by teams using ResFrac: collecting data, facilitating multidisciplinary discussions, calibrating to field diagnostics, and performing economic optimization of prospective designs.

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ResFrac Endurance Team: Race Reports

The team has been consistently busy over the last few months, but somehow along the way, our ResFrac Endurance team hasn’t stopped racing and training, setting and achieving goals. We have some race reports to share about the last few months of achievements. Join us in cheering for our ResFrac crew!

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ResFrac Updates: New Website, New Logo, and New Crack Propagation Algorithm (MuLTipEl)

ResFrac is releasing Egor Dontsov’s new crack propagation algorithm, MuLTipEl, a major new development in the field of fracture modeling. The algorithm tracks the position of the crack tip within each crack element, giving us unlimited spatial resolution to handle propagation across thin layers, and enables high accuracy 3D crack propagation calculations, even if using a relatively coarse mesh and accounts for detailed layering and heterogeneity of the formation.

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ResFrac Endurance Team

The ResFrac team has been going full speed this year! At our ‘virtual water-cooler’, I noticed that we have quite a few team members who are endurance and/or competitive athletes and did interviews to learn more about our athletic pursuits and how we have been able to fit athleticism in even around the most challenging schedules and in the craziest of years. Here are a few things I learned…

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Epistemic Challenges for Subsurface Engineering, Part II: Creating Value with a Hypothesis-Driven Workflow

How can we reconsider our approach to subsurface engineering in order to evaluate claims of truth and drive long-term value? I propose a hypothesis-driven approach, in which field testing is placed at the center of our efforts to assess the truth and improve over time. Physics-based and data-driven approaches are used as hypothesis-generating activities that motivate and prioritize hypothesis testing through field operations. Effective field testing requires the coordination of operations to enable clean well-to-well production comparisons and the design of data collection to enable strongly supported conclusions. Field testing need not increase the cost of field operations if it is done through intentional and thoughtful planning.

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Epistemic Challenges for Subsurface Engineering, Part I: The Persistence of False Beliefs

In a recent blog post, I outlined how companies use field tests, modeling, statistical analysis, and laboratory studies to improve over time. Information is synthesized as part of an iterative process of continuous improvement. In this post, I discuss what happens when the process of continuous improvement runs into trouble. In uncertain environments (like subsurface shale), there is a tendency toward overconfidence. We need to act, and in doing so convince ourselves that we are making the right decision. Sometimes we hire experts who ‘confidently confirm’ our beliefs. This is symptomatic of a phenomenon called confirmation bias, where we tend to ignore new data and outcomes that contradict our initial beliefs. After committing to strong claims, we may have difficulty changing course when it becomes apparent that they are not consistent with observations. This can cause false beliefs to persist for years, long after they have been falsified by field data.

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Holistic permeability correlation

Theoretical and Empirical Problems with the Holistic Permeability Correlation for DFIT Interpretation

In this post, I focus on a particular correlation that is sometimes used in the industry to estimate permeability from a shale DFIT: the ‘holistic permeability correlation.’ I show that this correlation can greatly overestimate permeability. When applied to optimize frac design, well spacing, and cluster spacing, overestimated permeability leads to significant loss of economic value.

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2020 ResFrac Symposium

Last month we hosted our annual ResFrac Symposium – our annual event for ResFrac customers. In keeping with the times, the event took place over

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ResFrac Office Hours

Join us for ResFrac office hours with the ResFrac team. Each Tuesday evening for at least the next four weeks, the ResFrac team will host

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HFTC 2020

HFTC is next week, and it looks like a great lineup. This week, I skimmed through about 40 of the papers that will be at

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Using RTA to Aid ResFrac History Matching

Using RTA to Aid ResFrac History Matching

Rate Transient Analysis (RTA) is commonly used to analyze production in unconventional reservoirs. The concept of RTA is to use rate signatures of producing wells to estimate properties such as permeability and fracture surface area. For more detailed analysis, fracture simulators, reservoir simulators, and coupled fracture/reservoir simulators, like ResFrac, can be used.

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The motivation of the DFIT study is that conventional DFIT interpretations are based on ‘preclosure’ and ‘postclosure’ calculations

DFIT Study Update

The DFIT Industry Study kicked off in January 2018 with six major operators and one service company participating. We have been holding meetings every three months, and the study will conclude at the end of 2018. The detailed results won’t be shared until next year. However, I can now provide a general update on the findings. I am really looking forward to sharing the full results!

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G-function plot of a typical DFIT.

Curving G-function plots and picking closure

G-function plots are routinely used to interpret diagnostic fracture injection test (DFIT) transients. Ideally, a plot of pressure versus G and G*dP/dG versus G should form a straight line. However, the G*dP/dG curve is very often curving. A typical DFIT transient is shown below.

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Derivative of pressure with respect to the G-function

Demystifying the G-function

Diagnostic fracture injection tests (DFITs) are commonly interpreted by plotting pressure versus a function of time called the G-function. The G-function seems rather arcane and is

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Diagnostic fracture injection test in a Cartesian plot.

How to plot a DFIT

Aside from the diversity of terminology, the diversity of plotting techniques is the aspect of DFIT analysis that most often causes confusion. Why don’t we just make

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