Executive Summary

Tayfun Babadagli, University of Alberta

My 3-year term as a co-Executive Editor of SPE Reservoir Evaluation and Engineering (SPE RE&E) will end effective the next SPE Annual Technical Conference and Exhibition in September. I am privileged to serve this position covering the Formation Evaluation section of the journal and will be handing it over to Dr. Francesca Verga. I wish her the best of luck in this service. Meanwhile, I would like to thank everybody who worked with me in this exhaustive review and publication process, including the SPE staff, technical editors, associate editors, and authors.

I would also like to take this opportunity to share some of my thoughts and observations collected over the last 3 years as an Executive Editor of SPE RE&E. Between January 2010 and March 2013, a total of 996 papers were submitted to SPE RE&E; 584 to the Reservoir Engineering part and 382 to the Formation Evaluation. The acceptance ratio has been nearly 15% and 20%, respectively. To one extent, this is an indication of the quality of the published papers, and therefore the journal as a whole. To another extent, this is a relatively low acceptance rate that speaks to the following points: (1) The number and quality of the submitted papers are not very high, and/or (2) the review process is meticulously selective. Both the editorial board of the SPE journals and I have been critical on these issues over the last 2 years. The given number of paper submissions mentioned above is not very low, but increasing this number will statistically affect the quality of the papers submitted. Specifically, authors are encouraged to submit their conference papers to the SPE journals for peer review. Having significantly increased the number of conferences and the number of SPE members over the last several years, we should receive more submissions for publications. This is really a big source to be used and, being aware of this, SPE sends invitations to the authors and invites them to consider their conference papers for publication in our journals. The number of papers we received for peer review should coincide with the number of conference papers submitted for presentation.

The quality of the reviews and the effectiveness of the review process should also be improved. Being self-critical on this, the editorial board of the SPE journals have worked on this and suggested some modifications for the review process. These modifications will be effective in a short period of time. In addition, technical editors are provided with training materials and workshops by SPE, and this has been a very useful practice for sustainable quality of the review process. I also have to mention that the average time for the first response to the authors has been approximately 3 to 4 months for SPE RE&E, which is reasonably good timing. Once accepted, the publication time of the paper is also relatively fast for our journal.

Over this 3-year period, I was also involved in discussions on restructuring SPE journals as a member of the editorial committee. Some suggestions were made as to reducing the number of journals (currently six), combining some of them, reducing the number of issues per year, or changing the publication media to online. There were several understandable reasons behind those suggestions, including declining journal subscription rates, accessibility of the published papers in the SPE journals through OnePetro, reducing number of paper submissions, and low acceptance rate. Regardless of all these issues, our efforts should be toward maintaining the continuity and sustainability of the SPE journals, as this is essential for the credibility of the journals. It should be remembered that these are not only documents published for the immediate needs of oil industry and interests of the members of our society, but more importantly to create collections for the next generations. I still read classical papers published in AIME Transactions that were published more than 4 to 5 decades ago and reference them to my students.

The continuity of our journals can be achieved not only through a sustainable subscription rate but also through improving the quality of papers, which requires increasing the number of paper submissions. This will eventually improve the quality of the papers (at least statistically). Efforts also have to be made toward the improvement of the impact factor of the journal. When the subscription rate and the impact factor ofSPE RE&E are cross-checked, we observe that the journal is widely read but the readers do not write as much. The same can be said for the other SPE journals. More efforts should be made toward encouraging the members of our society to write more.

Periodical modifications are always needed (and should be implemented) to improve the quality and sustainability of the journal based on the demands from the members of the society and the changing conditions in our industry. However, based on my experience of the past 3 years, I strongly believe thatSPE RE&E will continue to provide service to the society with its current structure.

In this issue of SPE RE&E, 10 papers under four different categories are included.

Performance of Fractured Wells

The paper Fractured-Well Performance Under Anomalous Diffusion presents a theoretical framework to pressure-distribution estimation in fractal fracture network structures. After providing a complete and rigorous solution using the Laplace transformations, potential use of the solutions was provided.

In Analytical Model for Unconventional Multifractured Composite Systems, the authors present an analytical model for multiple fractured horizontal wells in complex reservoirs as an extension of "trilinear flow." This solution is useful for branched fractures that are desired to improve the production performance. The model validated by numerical simulations will be useful for practitioners.

Core-to-Well-Scale Reservoir Characterization

The first of the two papers selected under this category, A New Approach in Permeability and Hydraulic-Flow-Unit Determination, reports a new approach developed analytically by coupling the Poiseullie and Darcy equations for a bundle of tortuous capillary tubes. The model was applied to an imaginary and then an actual sandstone field to determine the number of hydraulic units. It was shown that the distribution of hydraulic units as well as porosity-permeability relationships can be determined using this approach more accurately than conventional methodologies.

Relative permeability behavior of the representative carbonate rocks from Middle Eastern reservoirs was investigated in Variations in Bounding and Scanning Relative Permeability Curves With Different Carbonate Rock Types. Using a wide variety of imaging techniques and core-analysis methods, five different rock types were identified and steady-state relative permeability measurements at reservoir conditions were reported. The main focus in those attempts was to clarify the fluid-flow behavior for different zones and explain the reason behind the hysteresis. Significant variations in drainage and imbibition relative permeabilities for different rock types were observed and this was more obvious in imbibition water relative permeability curves.

Characterization of Tight Rocks and Shale Reservoirs

Four papers in this category studied different rock and reservoir characteristics of shale reservoirs using specific samples from North America, including Bakken, Montney, and Haynesville. Effect of Capillary Pressure on Phase Behavior in Tight Rocks and Shales reported a model that coupled capillary pressure and phase-equilibrium equations developed to improve the accuracy of ultimate-reserve calculations. A decrease in bubblepoint pressure was observed as the pore size gets smaller and increasing capillary pressures resulted in decreasing oil density. Several inexplicable behavior of the Bakken shales, such as the inconsistent gas/oil ratio behavior, high flowing bottomhole pressures, and low gas flow rate, were clarified by accounting the effects of small pore throats on pressure-volume-temperature properties.

The next paper, Water Distribution in the Montney Tight Gas Play of the Western Canadian Sedimentary Basin: Significance for Resource Evaluation, dealt with the determination of water distribution in the Montney tight gas reservoirs in Canada and observed that it is related primarily to large-scale stratigraphic architecture and rock fabric. The authors also provided a simple method to estimate effective-gas permeability using well logs and core data and related it to water saturation. It was shown that an understanding of water distribution and its influence on gas permeability can lead to determining “sweet spots” for field development.

In the paper Incorporating Geomechanical and Dynamic Hydraulic-Fracture-Property Changes Into Rate-Transient Analysis: Example From the Haynesville Shale, the authors incorporated stress-dependent matrix permeability and fracture conductivity changes into the rate-transient signature using pseudovariables (pressure and time). They observed a straightline linear flow/square-root of time plots for a multifractured well in Haynesville shales when both matrix and fracture permeability change effects are considered. The corrections provided will be useful in correcting the reserves estimations and forecasts.

The last paper in this category entitled Minidrillstem Tests To Characterize Formation Deliverability in the Bakken introduced the design of the minidrill stem tests (DST) tool and observed that the tool increased the reliability of pressure transient caused by minimized wellbore-storage effect compared with conventional DST and wireline formation tests. Another advantage of the tool was the significantly less time required than conventional DST and this enabled the testing of multiple zones for a given time. Also reported is the analyses of data obtained from the Bakken, which resulted in a better understanding of the flow mechanism during the primary production stage.

Nanoparticles in Reservoirs

The two papers in this category deal with the transport of nanoparticles in porous media and their effect on heavy-oil recovery. The Viscosity of Silica Nanoparticle Dispersions in Permeable Media studies the rheological characteristics of silica nanoparticles by conducting flow tests on unconsolidated (glass bead and sandpack) and consolidated (limestone and sandstone) porous media. It was reported that the viscosity depends on particle concentration and a correlation between nanoparticle concentration and dispersion viscosity was provided for different particle sizes. The retention of nanoparticles was observed only on the sandstone cores because of clay swelling.

In-Situ Upgrading of Heavy Oil/Bitumen During Steam Injection by Use of Metal Nanoparticles: A Study on In-Situ Catalysis and Catalyst Transportation also reported the transport characters and retention of nano- and micrometal particles in unconsolidated porous media to be injected to catalyze the aquathermolysis reactions during steam injection for heavy-oil recovery. Nanoparticle retention was observed in the range of 85 to 95% in unconsolidated porous media. Steam-soaking experiments yielded a higher quality of produced oil, faster oil recovery, and improved ultimate recovery (an additional 5%) when nanonickel particles were used for heavy-oil recovery. All these were attributed to increasing oil mobility and improved upgrading reactions because of the catalytic effect of nickel particles.

Tayfun Babadagli 
 Formation Evaluation Executive Editor