Unconventional/complex reservoirs

Unconventional and Tight Reservoirs-2022

Unconventional resource exploitation has three key technology and application focus areas—increasing implementation of fracture diagnostics, enhancing production and recovery from new well completions as well as existing wells through improved stimulation and restimulation design and execution quality, and developing enhanced oil recovery methods.

Unconventional Intro abstract

Unconventional resource exploitation has three key technology and application focus areas—increasing implementation of fracture diagnostics, enhancing production and recovery from new well completions as well as existing wells through improved stimulation and restimulation design and execution quality, and developing enhanced oil recovery methods.

With respect to diagnostics, the objective is a greater understanding of the reservoir and fracture geometry to determine optimal well spacing and completion design. The application of drawdown/buildup and rate-transient-analysis methods, previously confined to conventional reservoir evaluations, is now finding increased use in unconventional plays.

Regarding improved stimulation design and execution quality, unique laboratory evaluation methods are providing value by helping to determine optimal fluid chemistries to impart favorable fracture and contacted formation wettability and to optimize proppant transport. This becomes especially important with the increasing use or reuse of produced brines. New proppant compositions, size distributions, and delivery methods and design all call for focusing on effective quality control.

Optimization of new and existing well productivity can take unconventional resource exploitation only so far. Beyond that, the development of enhanced oil recovery methods, in conjunction with reducing CO2 emissions, for example, is a primary focus area for an increasing number of operators. CO2 huff ’n’ puff applications are most common, but other creative injection methods are being studied and trialed globally in tight formations, with potentially exciting prospects ahead.

This Month’s Technical Papers

Analysis of Post-Fracturing Pressure Tests Helps Develop Tight Sands Reservoirs

Field/Laboratory/Field Cycle Optimizes Fracture Placement, Well Performance

Machine Learning Optimizes Production in an Unconventional Reservoir

Recommended Additional Reading

SPE 208948 Deconvolution Overcomes the Limitations of Rate Normalization and Material-Balance Time in Rate-Transient Analysis of Unconventional Reservoirs by Leopoldo M. Ruiz Maraggi, The University of Texas at Austin, et al.

URTEC 208337 Innovative Stimulation Process for Sustainable Unconventional Resource Development by Roman Bilak, Terralog Teknologi Indonesia, et al.

SPE 201707 Laboratory Visualization of Enhanced Gas Recovery in Shale by Youssef Elkady, Stanford University, et al.


Leonard Kalfayan, SPE, is a principal adviser for production engineering and stimulation with Hess Corporation in Houston. He has 41 years of experience in the oil, gas, and geothermal industries. Kalfayan’s background is in production enhancement, new technology development and implementation, global technical support, and business development. Before joining Hess in 2009, he worked for the Union Oil Company of California and BJ Services and as an industry consultant. Kalfayan was a 2005 SPE Distinguished Lecturer and a 2013 SPE Distinguished Member. He has served on several SPE program and technical committees. Kalfayan is author of more than 30 SPE and other journal publications and holds 13 US patents. He is also author of the book Production Enhancement With Acid Stimulation, now in its second edition; coauthor of the book The Energy Imperative; and coeditor of the SPE monograph Acid Stimulation. He is a member of the JPT Editorial Review Board and can be reached at lkalfayan@hess.com.