D187 Low Resistivity Low Contrast Pay
D187 Low Resistivity Low Contrast Pay
Business Impact: Upon understanding the causes of a low resistivity, low contrast log (LRLC) signature and thus able to select an appropriate petrophysical model, the participants will be able to add to their company's reserve base. LRLC reserves can be identified in new-drill wells, and also in the re-evaluation of existing wells to identify bypassed or under-developed opportunities.
This course will provide a proven methodology to identify and evaluate Low Resistivity Low Contrast (LRLC) pays as seen in modern wells or as depositional bypassed pays in old wells. Worldwide examples from productive LRLC reservoirs will be discussed. The guest lecture, filling the morning of Day 3, will cover the applicability of some of the latest logging tools.
A virtual classroom course divided into 6 webinar sessions (equivalent to a three-day classroom course), comprising lectures, discussion, and case studies. Participants are encouraged to bring their own non-proprietary examples for end-of-the-day group discussion / evaluation.
Participants will learn to:
Although low contrast (LRLC) sands in the Gulf of Mexico Basin (GOM) were commonly considered wet, misidentified as shale or completely overlooked due to logging tool resolution, they have yielded significant volumes of hydrocarbons over the past 50 years. Low-resistivity pay has been typically defined at or below the 1.0 ohm-meter resistivity level, yet many productive reservoirs are found in the 0.3 to 0.5 ohm-m resistivity range. The interpretation of seismic response, the analysis of drill cuttings, sidewall and conventional cores, the interpretation of log response with the application of appropriate petrophysical models, along with wireline and production testing, can all contribute to an integrated LRLC evaluation.
Geological causes of LRLC pay include: laminated clean sands with shales; silts or shaly sands; clay-coated sands; glauconitic sands; sands with interstitial dispersed clay; sands with disseminated pyrite or other conductive minerals; clay-lined burrows; clay clasts; altered volcanic/feldspathic framework grains; very fine-grained sands; microporosity; or sands with very saline formation water. LRLC depositional systems include deepwater fans, with levee-channel complexes, delta front and toe deposits, shingle turbidites and alluvial and deltaic channel fills. The lack of high-resolution logging tools across intervals with reservoir sands below the tool resolution is frequently the “cause” of the LRLC.
Geological and petrophysical models developed in the GOM for the evaluation of LRLC pay are applicable in other world basins. A conventional Archie clean sand or Waxman-Smits shaly sand model are commonly used to evaluate LRLC log anomalies. Often, shaly sand models are not necessarily suited for LRLC evaluation. The Archie lithology exponent (m) and saturation exponent (n) for many LRLC reservoirs can range from 1.4 to 1.85, and from 1.2 to 1.8, respectively. In thinly laminated LRLC reservoirs, net sand distribution is identified with high resolution logging tools, the examination of rock samples and interval testing. Recent application of nuclear magnetic resonance logging has provided a better identification of fluid type, pore size distribution and hydrocarbon saturation in LRLC sands. Resistivity forward modeling can also aid in establishing the “true” resistivity in laminated sands. This course will provide a proven methodology to identify and evaluate LRLC pays as seen in modern wells or as potential bypassed pays in old wells.
The guest lecture on the morning of Day 3 examines recent developments in low resistivity pay and shaly sand analysis, including Multicomponent Induction Resistivity for identification of thin beds, Elemental Capture Spectroscopy for mineral and clay volumes and Nuclear Magnetic Resonance for pore size distribution.
The course is intended for exploration and development professionals who are working in environments where LRLC sands may be present and for those who are evaluating these difficult sands.
A basic familiarity with petrophysical evaluation is assumed, as presented in N083 (Petrophysics: Basic Principles and Practices) or N121 (Modern Petrophysical Well Log Interpretation). The topics covered by the Guest Lecture are more fully developed in N314 (Advanced Petrophysics for Conventional Reservoirs).
Over 37 years experience in petrophysical and petroleum-engineering studies integrating log interpretation, rock data, and reservoir performance. His specialty projects include::
• Multi-well exploration, appraisal and development in shaly clastic reservoirs and complex carbonate lithology
• Unconventional resources including coalbed methane, tight gas, shale reservoirs, and heavy oil
• Property valuation for mergers and acquisition
• Reserve certification
• Log-seismic interrelationships
• Mentoring of client staff for NOC’s and independents
John is a recognized authority in the identification and evaluation of low resistivity, low contrast (LRLC) pay zones and has presented courses and seminars worldwide. He is an expert witness at the Texas Railroad Commission and for other judicial courts.
Affiliations and Accreditation
MSc University of Houston (Magna cum Laude) - Petroleum Engineering
BSc University of Pittsburgh (Magna cum Laude) - Petroleum Engineering
Member of the SPE, SPWLA, AAPG and HGS
N141: Unconventional Petroleum Systems: Exploration for Tight Gas Sands
N187: Low Resistivity Low Contrast
David joined Shell Offshore in New Orleans, Louisiana as a petrophysicist where he had various assignments in production and exploration, covering all areas of the Gulf of Mexico. He worked for Pecten International, Shell’s global affiliate, in 1994, and focused on exploration in West Africa. In 1996, he moved to Shell’s South Texas Gas Asset team and worked on the development of Wilcox tight gas sands. From 1999 to 2011, David worked with Marathon Oil Corporation where he had exploration/operations assignments for Gulf of Mexico and Angola and a field development assignment for a Sirte Basin discovery in Libya. David retired from Marathon in 2011 and is now teaching industry courses.
David has a broad range of interests within petrophysics, but specializes on the elastic properties of rocks and how seismic attributes can be used to explore for and develop hydrocarbon reservoirs. Other areas of interest are compaction and quartz cementation modeling of clastics for reservoir quality prediction. He has extensive experience in log and core data acquisition as well as reservoir characterization.
Affiliations and Accreditation
BSc California Polytechnic State University - Mechanical Engineering
Society of Petrophysicists and Well Log Analysts
American Association of Petroleum Geologists
N054: Skilled Petrophysical Methods for Conventional Reservoirs
N083: Petrophysics and Formation Evaluation: Principles and Practice
N187: Low Resistivity Low Contrast Pay
N314: Advanced Petrophysics for Conventional Reservoirs
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