Welcome to the August issue of SPE Production & Operations. There was, as usual, a rich selection of papers to choose from for this issue, so I have again been able to focus on three areas to give you a diverse choice of papers. This issue starts with a paper that deals with a wells-related issue. We then move onto improved recovery (I think that you will enjoy the paper that describes the conditions necessary for improved oil recovery resulting from seismic events), and end with four papers that all have chemistry as an underlying theme. We receive a significant number of oilfield-chemistry papers, and I could probably fill each issue with them. However, even I would find that boring, so I always stretch myself to include papers in areas that I’m not technically involved with.
Before beginning the overview of the papers included in this issue, I would like to thank the associate and technical editors for their dedication and effort in the first half of the year—it has been a busy time, and we have all had a hard time keeping up. The number of submissions to the journal is increasing, and I see a rise in the quality of the papers, which is leading to an increase in the acceptance rate, all of which means more work for the review team. I hope that you enjoy the fruits of our labor!
The first paper in this issue discusses liquid loading in gas wells—see A Pragmatic Approach To Understanding Liquid Loading in Gas Wells. Liquid loading is the inability of a producing gas well to remove its coproduced liquids from the wellbore. This paper investigates the deliquefication of gas wells by use of fluid and heat-flow modeling of the entire wellbore. The authors are able to demonstrate an improvement on existing methods for tackling this problem.
We move on to a series of papers that discuss aspects of improved oil recovery. The presence of oxygen and carbon dioxide in the injection—and production—streams of (high-pressure) air-injection projects can create serious safety issues, such as the potential for explosion or corrosion. Safety Considerations for High-Pressure Air Injection Into Light-Oil Reservoirs and Performance of the Holt Sand Unit Project discusses this problem, and provides best practices for the future operation of high-pressure air-injection projects. Measurement and Correlation of Solubility and Physical Properties for Gas-Saturated Athabasca Bitumen discusses the development of an understanding of the phase behavior of carbon dioxide/Athabasca-bitumen mixtures. The reason that it is important to understand this is because the addition of hydrocarbon, or nonhydrocarbon gases, to steam can have a beneficial effect on the performance of steam-based processes for the recovery of heavy and extraheavy oils. Investigation of the Conditions Required for Improved Oil Recovery by an Earthquake shows that there is a clear relationship between earthquakes and temporarily improved oil recovery for a small oil field located in a seismically active region of Japan. The study identifies the conditions required for an earthquake to temporarily improve oil recovery. The only European polymer enhanced-oil-recovery pilot is in Austria at the Matzen Field. It has been an excellent opportunity to gather operational experience and knowledge, and these learnings are summarized, together with the supporting data, in Operational Challenges and Monitoring of a Polymer Pilot, Matzen Field, Austria.
We start our examination of oilfield chemistry with a paper that discusses accelerating the gelation of hydrolyzed polyacrylamide (HPAM)—see Evidence of the Gelation Acceleration Mechanism of HPAM Gel With Ammonium Salt at Ultralow Temperature by SEM Study. The aim of this work was to investigate the relationship between gelation performance and the microstructure of the target gel by scanning-electron-microscope (SEM) under different test conditions. We then move on to a related paper, Use of Hydrochloric Acid To Remove Filter-Cake Damage From Preformed Particle Gel During Conformance-Control Treatments, that discusses the effectiveness of using hydrochloric acid (HCl) to remove gel cakes induced during conformance-control treatments. This study is focused on preformed particle gels (the particles are millimeter-sized) that have been used to control water flow through super-high-permeability zones (and fracture zones) in mature oil fields. When the gel is injected into target zones, the gel can form a cake on the surface of low-permeability, un-swept parts of the reservoir section, which must be removed.
We change our focus with the final two papers. The Use of PPCA in Scale-Inhibitor Precipitation Squeezes: Solubility, Inhibition Efficiency, and Molecular-Weight Effects describes studies on phosphino polycarboxylic acid (PPCA) scale inhibitors. In this comprehensive study, the importance of the molecular-weight distribution (MWD) of the inhibitor on its ability to prevent scale formation is highlighted. Furthermore, it is shown that the MWD controls the return of the PPCA during a precipitation squeeze treatment and, hence, impacts the lifetime of the treatment.
Finally, Predicted and Observed Evolution of Produced-Brine Compositions and Implications for Scale Management uses geochemical modeling and scale prediction to understand the composition and scaling risk of produced water samples. The use of geochemical modeling was able to describe the evolution of the produced-brine compositions at the production wells, allowing the authors to test assumptions about the in-situ reactions occurring in the reservoir. The ultimate aim of the study is to improve scale management by providing an understanding of the composition of the produced water.
It is a struggle allocating our accepted papers to a journal issue, and there are many excellent papers that have been accepted by the journal that are awaiting publication in the journal. These are all available online at OnePetro, so please do have a browse and see what is new in your field. Whilst you are online, take a look at the SPE events page (http://www.spe.org/events/calendar/) to see if there are any meetings or other events that might be of interest.
Ian Collins, BP Exploration