Executive Summary

Welcome to the February 2019 issue of SPE Production & Operations. I am glad that many papers related to acidizing are being published in this issue. Over the past year or so, I have noticed a reduction of papers in the matrix-stimulation area. A quick search through the published papers in SPE Production & Operations and its predecessors SPE Production & Facilities (1993–2005) and SPE Production Engineering (1986–92) shows that the number of matrix-acidizing papers dropped significantly during the periods from 1990 to 1992, 1996 to 1997, 2001 to 2004, and in 2015, whereas the drop in fracture-stimulation papers occurs only in 1997, 2002 to 2004, and in 2014. Although there is often a lag between when a paper is first prepared by the authors to the time it is peer reviewed and published in the journal, we may still be able to vaguely correlate the impact on publication with the up and down cycles and the technology trend of the industry. It seems not that long ago that matrix acidizing, particularly in carbonate reservoirs, was a very popular subject in the research and publication domain. Acid-rock kinetics studies, wormholing patterns, and diversion methods and materials were often discussed at conferences and in the literature. One most commonly cited phrase in papers was “more than 60% of the world’s hydrocarbon is produced from carbonate reservoirs.” Of course, sandstone acidizing has long become a lost art since probably the late 1990s to early 2000s.

Among the acidizing papers in this issue, two papers prompt me to share some thoughts in terms of technology development and evolution in our industry: Dendritic-Acidizing Update: The Light at the End of the Tunnel and Tunnel-Length Modeling for Coiled-Tubing-Acid-Tunneling Stimulation in Carbonate Reservoirs. This interesting idea was conceived with the goal of overcoming the disadvantages of coiled-tubing drilling (SPE-68439-MS) in 2001. The current two papers describe this process and technique not for drilling the main wellbore in reservoirs composed of reactive rocks, but more predominantly for stimulation of such reservoirs. I still remember listening to the presentation of this technology in a conference many years ago. I was puzzled by its feasibility and wondering how many people in the industry would actually pay attention to it. Nearly 20 years later (yes, time flies), I am in awe to see that tools have been developed and real field operations have been executed. I have to applaud the passion and tenacity of the developers and their companies for believing, adapting, and revising to materialize an ambition; more significantly, persevering through the upturns and downturns over such a period of time. Of course, how broadly the technology is used and how much it differentiates itself from other solutions in addressing the challenges will eventually determine its fate in the commercial world. As the technology approaches the end of the tunnel, I would look forward to seeing case studies that clearly articulate the value of such technology; likewise for any technology. The reader can become more knowledgeable about what benefit a technology can bring and for what applications a technology is best suited.

In addition to the acidizing papers highlighted in this issue of the journal, there are many good papers in various technical domains as they are categorized below. I hope you enjoy reading them.   

Environment and Safety

  • An Assessment of the Probability of Subsurface Contamination of Aquifers From Oil and Gas Wells in the Wattenberg Field, Modified for Water-Well Location, C. H. Stone, W. W. Fleckenstein, and A. W. Eustes
  • Automatic Flare-Stack Monitoring, R. Janssen and N. Sepasian

Completion Performance and Production Optimization

  • A Cost/Benefit Review of Completion Choices in the Williston Basin Using a Hybrid Physics-Based-Modeling/Multivariate Analysis Approach, M. Mayerhofer, O. Oduba, K. Agarwal, H. Melcher, E. Lolon, J. Bartell, and L. Weijers
  • Analysis of Well-Completion Performance and Production Optimization of a Gas Well Using Computational Fluid Dynamics, O. M. Molina and M. Tyagi
  • 3D Hydraulic-Fracture Simulation Integrated With 4D Time-Lapse Multicomponent Seismic and Microseismic Interpretations, Wattenberg Field, Colorado, A. Alfataierge, J. L. Miskimins, T. L. Davis, and R. D. Benson
  • Real-Time Production Optimization of Steam-Assisted-Gravity-Drainage Reservoirs Using Adaptive and Gain-Scheduled Model-Predictive Control: An Application to a Field Model, R. G. Patel, V. Prasad, and J. J. Trivedi

Matrix Acidization

  • Anisotropic-Wormhole-Network Generation in Carbonate Acidizing and Wormhole-Model Analysis Through Averaged-Continuum Simulations, M. P. Schwalbert, D. Zhu, and A. D. Hill
  • A Robust Model To Simulate Dolomite-Matrix Acidizing, M. T. Ali and H. A. Nasr-El-Din
  • Dendritic-Acidizing Update: The Light at the End of the Tunnel, C. D. Wehung, S. K. K. Latimer, and D. R. McDuff
  • Effect of Natural Fractures on Wormhole-Propagation Behavior, J. Mou, X. Yu, L. Wang, S. Zhang, X. Ma, and X. Lyu
  • Tunnel-Length Modeling for Coiled-Tubing-Acid-Tunneling Stimulation in Carbonate Reservoirs, S. Livescu, S. Craig, and B. Aitken
  • Effect of Dilute Acid on Hydraulic Fracturing of Carbonate-Rich Shales: Experimental Study, T. W. Teklu, D. Park, H. Jung, K. Amini, and H. Abass
  • Stimulation of High-Temperature Steam-Assisted-Gravity-Drainage Production Wells Using a New Chelating Agent (GLDA) and Subsequent Geochemical Modeling Using PHREEQC, Z. O. Ameur, V. Y. Kudrashou, H. A. Nasr-El-Din, J. P. J. Forsyth, J. J. Mahoney, and B. J. Daigle

Organic Scale

  • Re-Evaluation of Asphaltene-Precipitation Risk Depending on Field-Operational-Condition Change/Variation: Case Study Comparing Risks in Past (2008) and Present (2016) for Future Prediction, K. Takabayashi, A. Shibayama, T. Yamada, H. Kai, M. T. Al Hamami, S. Al Jasmi, H. B. Al Rougha, and H. Yonebayashi
  • Study on Wax Removal During Pipeline-Pigging Operations, W. Li, Q. Huang, W. Wang, Y. Ren, X. Dong, Q. Zhao, and L. Hou
  • Unconventional Gas-Dehydration-System Failure Resulting in a Gas-Hydrate Blockage, J. D. Sundramoorthy, M. J. Leknes, and K. Moodley

Multiphase Flow Dynamics

  • Estimation and Analysis of Carbon Dioxide Friction Loss in Wellbore During Liquid/Supercritical Carbon Dioxide Fracturing, X. Li, G. Li, K. Sepehrnoori, W. Yu, H. Wang, Q. Liu, H. Zhang, and Z. Chen
  • Oil/Water Pipe-Flow Dispersions: From Traditional Flow Loops to Real Industrial-Transport Conditions, A. Schmueli, T. Erling Unander, and H. Schümann
  • Particle-Transfer Between the Cyclone and Accumulator Sections of a Desander, C. H. Rawlins

Frank Chang, SPE Prod & Oper Executive Editor,
Saudi Aramco