Environmentally Compliant Geoenergy:
Advanced Geomechanics Research
M. Rafiqul Awal, Ph.D.Office: PE 211D
A chapter from the book Environmentally Conscious Petroleum Engineering (John Wiley, 2010).
The book opens with a chapter on environmental consciousness in the petroleum sector, spurred by rising global ecological awareness and government regulation in the Western Hemisphere after World War II, the product distribution and marketing sector, as well as oilfield operators, have taken proactive roles in planning their operations with almost zero tolerance for environmental damage.
Investment Opportunity for Energy Companies
Figure 1. Proof of rubble-free complex fracture network (CFN) created by the new Plasma Tool.
The above is a slice from micro-CT Scanner imaging (one of hundreds, taken 1.5 mm apart), after fracturing a 115-lb confined cement block (12-inch diameter, 18-in long; dark circle at center shows water-filled wellbore. The image slices show continuous radial fractures, without any enlargement or deformation of the wellbore (no rubbles). The CFN has been reproduced by testing many control samples. The Plasma Tool is 16-times more efficient compared to High Energy Gas Fracturing (HEGF) method using propellants (basis: Stimulated Fracture Volume per unit Input Energy). By repeated plasma shots (50-100) at each wellbore location, the multiple radial fractures are widened as well as extended deep inside the reservoir volume.
Environmentally Friendly "Fracking" Invention
Plasma Stimulation & Fracturing Technology
A new non-hydraulic fracturing method requiring no pumping fleet and fracturing fluids
The new technology, Plasma Stimulation & Fracturing Technology (PSF) was invented and is being developed in-house since February 2010 (without publication for IP protection). PSF creates multiple radial fractures of self-propped type fractures (see Figure 1) by fast-expanding plasma generated using a proprietary, high-energy pulsed-power electrical discharge technique. While the plasma tool alone can create 5-20 ft long multiple radial fractures of self-propped type, the implementation of the pulse stepping algorithm can extend these fractures over 50 ft. Needless to say, PSF is a 100% environment-compliant technology, deployable with almost invisible foot-print (unlike hydraulic fracturing) of a couple of ten-wheel trucks: no surface or subsurface water contamination, noise pollution, and atmospheric emissions. With growing concerns over environmental concerns and resource crunch issues associated with hydraulic fracturing, and the growing discoveries of shale-gas and shale-oil resources in the Americas, China, and Europe, the potential of PSF as a disrupting technology is rising.
Types of Applications:
PSF can be custom-designed for use in both conventional and unconventional oil and gas reservoirs. The PSF technology is a product of the inventor's twenty years of applied research in geomechanics and adaptation of Cold War era defense research in pulsed-power engineering. With technical assistance from Texas Tech University's Center for Pulsed Power & Power Electronics, the first PSF prototype was built and intensive in-house research has been conducted by the inventor. As a result, two technologies emerged: a proprietary hardware (plasma tool) for generating high intensity, micro-second duration shockwave pulse, and an application algorithm (pulse stepping).
PSF is a non-hydraulic fracturing method that requires no pumping fleet and associated fracturing fluids and proppants. In contrast to near-static pressurization by hydraulic fracturing, PSF employs multiple cycles of extremely fast (micro-seconds) dynamic pressurization in the wellbore. The multiple radial fractures created by PSF are self-propped because of a phenomenon, known in geomechanics engineering as shear displacement. This phenomenon occurs by virtue of emergence of shear stresses along the newly created fracture planes aligned in the directions of non-principal in-situ stresses. Hydraulic fracturing never generates such shear stresses along the bi-wing fractures, which are aligned in the direction of principal stress.
Technology Readiness Level:
Based on intensive studies conducted with the PSF prototype (see Figure 2), and energy-vs.-fractured volume benchmark comparisons with propellant fracturing technology (both laboratory and field data), the design parameters for upscaled field prototype have been established. Using this know-how a Pilot Project can be undertaken. The Project will entail fabricating the PSF hardware for demonstration in 10,000 ft TVD vertical or horizontal well. (The estimated revenue from PSF job is approx. $1,000 per foot of depth.)
Figure 2. World’s first Plasma Fracturing Prototype—conceived and designed by Dr. Awal.
The 5-kJ electrical pulse output system, together with a proprietary Pulse Stepper Algorithm (PSA) can extend the multiple, radial fracture networks deep inside the reservoir. Modest 50-ft long MRFs spanning continuously along a horizontal well in shale-gas/oil reservoir can produce more reservoir contact area (up to 2 order of magnitude) than hydraulic fracturing. Shockwave fracturing by chemical propellants (HEGF) are constrained for PSA application.
Core Features of Plasma Stimulation & Fracturing Technology:
The plasma tool’s core technology is a pulse power driven shockwave module for generating controlled and precision stress pulses in the wellbore—both cased and uncased. This is a quantum jump in well stimulation and fracturing technology—a truly 4th generation fracture stimulation technology since the advent of hydraulic fracturing technique (1947). Since mid 1980s scientists have tried to use high-voltage, high-current electrical pulse to generate expanding plasma by means of spark-gap or wire discharge methods (Wesley, 1984; Ayers & Wesley, 1995; Rey-Bethbeder et al., 2012; Chen et al., 2012; Chevron 2012—references furnished separately); however, these methods—at experimental level and devoid of advanced knowledge of geomechanical behavior of rocks, are considered antique compared to the proprietary method used in PSF hardware, which is an advanced generation of electrical-to-pressure energy conversion method developed at US Naval Surface Warfare Research during the late Cold War era, and exploitation of hyper-fast strain rate behavior of rocks based on inventor’s two-decade’s research in applied geomechanics. The prototype PSF hardware built in February 2010 and tested on large blocks of controlled properties established data to build field-scale plasma tool for demonstration in deep wells.
PSF is an advanced form of earlier shockwave-induced fracturing techniques: explosive fracturing (1960-70) developed at US National Research Laboratories’ (Sandia and Los Alamos), which can be considered as 2nd generation, and propellant fracturing (1975-85) developed through several Devonian Shale projects sponsored by the US Department of Energy (3rd generation fracture). The failure of explosive fracturing method to achieve fracture length of practical significance led to the quick demise of explosive fracturing method. The next generation propellant fracturing method produced longer fractures, in the 2-25 ft range, which were considered inadequate compared to the popular hydraulic fracturing method. However, the fact that propellant fracturing method produced multiple radial fractures (4 to 7) was ignored by US oil and gas industry. As China adopted new economic policies since 1985, the state-owned Chinese oil companies began using propellant fracturing method for bypassing near-wellbore plugged zone (caused by drilling mud invasion, or fines migration with oil and gas), reporting a very high success ratio (over 85%). The US oil and gas industry still uses matrix acidization method for such purposes. Matrix acidization is not only less successful for well productivity enhancement; it has significant health, safety, and environmental concerns.
Plasma Stimulation & Fracturing: A true cutting-edge technology
Figure 3. Pulsed Arc Electrohydraulic Discharges (PAED), invented by French scientists (September, 2012)
The PSF method overcomes the ‘inadequate’ fracture length issue by virtue of the nature of the hardware, which enables repeated generation of needed stress pulses at a given wellbore interval over a few minutes, without moving the hardware. This is impossible to achieve with current commercially available propellant fracturing methods. Unlike propellant fracturing method, proprietary hardware used in the PSF method also makes possible a wide spectrum of shockwave pulse generation, and can be customized for specific rock types (sandstone, carbonates, and shales).
In addition to the hardware advantage based on advanced pulsed-power to shockwave conversion technique, an innovative methodology to extend fracture lengths (50 ft+ each, 4-7 multiple radial fractures) has been developed. Thus the PSF enjoys a quantum lead ahead in the ongoing race for developing pulsed-power engineering based fracturing method.
Figure 4. ExxonMobil's large Indiana Limestone block (left, 14-cubic ft), with wormholes created by matrix acidizing (right, CT scanned image).
Shale Fracturing by Shockwave: A joint industry project in France (where hydraulic fracturing is banned) led by University of Pau, and funded by large oil company, TOTAL, recently developed a lab prototype (Figure 3) for non-hydraulic fracturing: Pulsed Arc Electrohydraulic Discharges (PAED). However, PAED employs a 1st generation, very low efficiency (~10%) electric-to-shockwave conversion (ESC) process, compared to Texas Tech’s 3rd generation highly energy efficient (70-80%) process. Besides, PFS continues its lead by growing into a full scale prototype for field demonstration.
Matrix Acidizing: To bypass formation damage, ExxonMobil (JPT Oct. 2010) claimed that matrix acidizing to create wormholes (Figure 4) up to 20-ft might be possible to create (not yet reported). Compare Figure 4 with Figure 1, and it is easy to see the superior productivity enhancement and/or bypassing of near-wellbore formation damage zone by PFT technology, which is 100% Green, compared to hazardous and environmentally problematic matrix acidizing.
[Additional information can be furnished upon request by research sponsors and collaborators]
New Graduate Course and Undergraduate Program
New Graduate Course:
(Summer I and II)
- Applied Petroleum Geomechanics
Undergraduate Research Program (on the anvil)
Summer (June, July, and August)
- Summer Accelerated Research Internship (SARI) for Developing Environmentally Compliant Geo-Energy Technology
Goals and Objectives
The SARI program is intended for undergraduate students or current graduates (with no graduate course-work) who wish to gain more research experience before entering graduate school. The SARI Program aims at harnessing talented undergraduate engineering students in U.S. engineering schools toward meeting the growing challenges of empowering the nation with clean energy. SARI is cognizant of the facts that most U.S. university research programs are manned by foreign graduate students, while most U.S. undergraduates are not retained in academia because of the lack of competitive scholarships comparable to professional benefits offered by the E&P industry. Because of the lack of talented graduate students, the geo−energy research programs in U.S. universities have not stood up to the challenges. Therefore, SARI aims to fill this vacuum by attracting young American students with an attractive scholarship package and professionally rewarding research opportunities, scheduled during summer sessions.
The SARI program is developed to conduct supervised research in three broad fields:
- Environmentally compliant fracking (EnFrack) technology as alternative to Hydro−fracking, such as, innovative applications of shockwave and thermal methods.
- Novel well completion methods, using Induced Stress-Cage Effect and EnFrac.
- Advancement of ANG technology (Adsorbed Natural Gas) for energy storage-cum-transportation.
The SARI program will introduce its interns to a full−time work schedule, which can be a first−time experience for many. During the 10−week program, interns will be exposed to the life of a graduate student, as well as learn to become more independent and self-motivated. Interns will be exposed to and helped by their mentors, graduate students, other staff members, and the Whitacre College of Engineering’s administration.
- Ten petroleum engineering senior students, selected on merit basis by program committee through a review process of applications.
- A full stipend is predicated on the 10−week period, for a total of $5,000 per student.
For participating students and faculty:
- Prepare NSF proposal under REU Program (REU—Research Experience for Undergraduates).
- Retain high−caliber U.S. students for graduate program (SARI to create motivation for pursuing graduate studies and research).
- Career enhancement: Successful students will receive a Certificate of Research Merit (CRM).
- Augmented employment opportunities for CRM students with sponsoring and other E&P companies.
For participating E&P companies:
- Hiring opportunity of high−performing graduates.
- Direct Technology Transfer of, and/or licensing opportunity for commercially potential research outcomes.