Executive Summary

A happy belated New Year to our readers and welcome to the first edition of 2017. Gratifyingly, I noticed an improvement in the quality of papers submitted to the journal in 2016, with many only needing one round of revisions and indeed some papers needing no technical revisions at all. This is reflected in the papers that I had available to choose from, and I hope that this is also reflected in the paper selections for this issue. In reflecting on the papers that have been submitted to us in 2016, I have noticed more of what could be termed “novel technology” papers, such as the use of nanoparticles. Such papers used to be mainly submitted to the more academic literature, and I think the fact that we are now seeing applications of such technology shows how far the science has evolved. Of course, there is some way to go to routine field application, and I realize how much you like practical papers that can be used in the oil field, but I do like to be able to give these nascent ideas an airing, so I hope to be able to publish more application-based papers deploying novel technology in 2017.  

In this issue, I have again tried to be broad in the technical areas featured despite half of the available papers being chemistry related! This issue starts with two papers that deal with the artificial lift. We then move onto a paper that overlaps with our sister journal SPE Drilling & Completion, discussing the environmental and technical challenges of cementing. We are publishing it because it has a chemistry focus and discusses in depth the environmental challenges involved in cementing operations. The next section deals with fracturing technology. The last paper in this section could be considered a chemistry paper because it deals with acid fracturing in shales and so provides a nice link into the final section that has papers related to production chemistry–two dealing with mineral scale deposits and two with organic deposits.

Again, I cannot emphasize enough the dedication and professionalism of the Associate and Technical Editors. It is down to their hard work and effort that we have so many good papers to publish, and I am sure you will join me in saying a big thank you for all of their efforts in 2016.

The first paper in this issue, An Enhanced Model for the Design of Tapered Sucker-Rod Strings, discusses sucker-rod design. Rod strings designed by currently available procedures do not usually have comparable safety profiles for different rod tapers. This paper introduces a novel procedure that enables a predictive solution of the damped-wave equation during the design of the sucker-rod, allowing different rod tapers to have similar fatigue profiles and, overall, a greater safety margin than conventional design allows. A closely related paper is Prediction of Maximum Possible Liquid Rates Produced From Plunger Lift by Use of a Rigorous Modeling Approach. This paper introduces a reliable predictive model that can be used to check on maximum possible liquid-production rates by use of plunger lift. The method uses tubing size and well depth as controlling parameters for the accurate prediction of maximum possible liquid rates produced from plunger lift. Finally, Overcoming Environmental and Technical Challenges for Well Cementing: A Global Perspective addresses numerous distinct challenges for cementing-related fluids and how the changing regulatory requirements across different regions can be managed optimally. An innovative “green” chemistry solution for high-pressure/high temperature operations is used as an example of the process.

We move on to a series of papers that discuss aspects of fracturing. Use of a CO2-Hybrid Fracturing Design To Enhance Production From Unpropped Fracture Networks introduces a new CO2-hybrid fracturing design that intends to significantly improve production from unconventional reservoirs and reduces the need for freshwater. The design consists of first injecting pure CO 2 as the pad to generate a complex fracture network, and second, injecting a gelled slurry to generate near-wellbore conductivity. Numerical Analysis for Promoting Uniform Development of Simultaneous Multiple-Fracture Propagation in Horizontal Wells discusses the low effectiveness of multiple fracture treatments. These treatments do not take the same amount of fluid and proppant because of the interaction between hydraulic fractures (i.e., stress-shadow effects). Unfortunately, how best to minimize the negative effects of stress shadowing is still not fully understood in our industry. In this paper, the authors analyze this problem and develop a complex hydraulic-fracture-development model that can be used to promote more-uniform fracture growth.

Understanding how acid dissolution changes the microstructure, petrophysical properties, and pore structures of shale is essential in the design and application of acid-fracturing treatments. Acid Fracturing in Shales: Effect of Dilute Acid on Properties and Pore Structure of Shale shows the in-situ changes of microstructure and pore structure in shale before and after acid fracturing for the first time. These data are discussed in the context of improving acid fractures in shales.

We start our discussion of production chemistry with a paper on vapor/liquid-equilibria (VLE) calculations. Calculations involving the phase behavior of CO 2 and hydrogen sulphide are used in scale-prediction modeling and The Impact of Vapor-Liquid-Equilibria Calculations on Scale-Prediction Modeling discusses the impact of acid- and sour-gas mixtures on scale-prediction calculations by use of the VLE approach. Uncertainty over the composition of formation water can make the decision to inject normal seawater or low-sulfate seawater into a reservoir for pressure support a challenge. The Johan Sverdrup Field: Origin of Sulfate-Rich Formation Water and Impact on Scale-Management Strategy discusses the techniques used to assess the composition of the formation in the Johan Sverdrup Field on the Norwegian Continental shelf and the implications for an effective scale-management strategy.

We change our focus with the final two papers. A Mechanistic Understanding of Asphaltenes Precipitation From Varying-Saturate-Concentration Perspective describes systematic characterization of 11 different bitumen and crude-oil samples using density and viscosity measurements and the determination of the elemental composition and saturates, aromatics, resins, and asphaltenes (SARA). Further analyses were carried out to determine the asphaltene onset point, the Fourier transform infrared spectrum of the bulk oils, and the cluster size of precipitated asphaltene aggregates and their zeta potential. These data were synthesized to develop a model of asphaltene stability. 

Finally, Experimental Study of Paraffin Deposition Under Two-Phase Gas/Oil Slug Flow in Horizontal Pipes gives a comprehensive data set on the deposition of paraffin wax under both single-phase and multiphase flow. Multiple measurements are used to characterize the location of the deposits, the thickness of the deposits, and their composition, leading to a detailed understanding of the different deposition regimes and the impact on pipeline wax deposition.

A continuing theme I always find when deciding on the papers to feature in each issue of the journal is that I am overwhelmed by choice. There are many excellent papers that are awaiting publication in the journal and may not see actual publication for 12 months. So please check online at OnePetro ( https://www.onepetro.org), where all of our accepted papers are available for download.  

Ian Collins, SPE Prod & Oper Executive Editor; 
BP Exploration