Welcome to the first 2016 edition of SPE Production & Operations. I enjoyed selecting the papers for this issue because it allowed me to reacquaint myself with a couple of areas of oilfield chemistry that I haven’t been involved with for a few years and to continue my education in wells hardware! It has also been a distraction from the oil price and the continuing consequences for the industry. Like many of you, I’m sure, I try to take every opportunity to become engrossed in some deep technical work and feel like I’m doing something useful. SPE provides an excellent range of resources to support us in developing technical excellence, publications being only one route to information and learning. For example, the current and archived webinars are all available at https://webevents.spe.org/.
We have three themes in this issue—oilfield chemistry, hydraulic fracturing, and artificial lift. The first paper in under oilfield chemistry discusses calcium carbonate scaling. A Practical Method of Predicting Calcium Carbonate Scale Formation in Well Completions focuses on describing an empirical method to predict the potential rate of scale formation under realistic conditions for intelligent-well completions in which the interval-control-valve opening must be changed to control flow rate. The completion will become ineffective if plugging by scale desposits prevents valve actuation. The paper cleverly integrates chemical data with flow fields generated by computational-fluid-dynamics models for downhole tools. Such mineral scale damage and plugging is often remediated in the field by use of scale dissolvers that are based on organic chelants. These chelants can decompose at high temperatures, and Thermal Stability of Oilfield Aminopolycarboxylic Acids/Salts describes laboratory experiments to measure the thermal stability of a variety of different chelants, allowing the most effective chemical to be selected for scale dissolution.
We move away from mineral scale management to an excellent paper that discusses drilling and completion fluids—Formate Drilling and Completion Fluids: Evaluation of Potential Well-Productivity Impact, Valemon. Valemon, operated by Statoil, is a high-pressure/high-temperature gas/condensate field on the Norwegian Continental Shelf. A potassium/cesium formate water-based drilling-and-completion fluid with a density of 2.02 specific gravity was considered for the wells completed with screens in this field, and the paper describes the selection and qualification process that was used by Statoil.
Our final paper on oilfield chemistry provides a nice bridge to our discussion of well-completion technology. Interactions of Fe(III) and Viscoelastic-Surfactant-Based Acids describes viscoelastic-surfactant (VES)-based acid systems used for matrix-acidizing and acid-fracturing treatments. However, the existence of Fe(III) as a contaminant in such systems often leads to many problems because of the interaction between the VES and Fe(III). In this paper, two commercial VES products were studied, and the interactions between the VES and Fe(III) investigated in detail, which should allow more stable formulations to be developed.
We start our discussion of hydraulic fracturing with a paper that describes Poroelastic and Poroplastic Modeling of Hydraulic Fracturing in Brittle and Ductile Formations. The prevailing approach for hydraulic-fracture modeling relies on linear-elastic fracture mechanics (LEFM). Generally, LEFM using the stress-intensity factor at the fracture tip gives reasonable predictions for hard-rock hydraulic-fracturing processes, but often fails to give accurate predictions of fracture geometry and propagation pressure in formations that can undergo plastic failures, such as poorly consolidated/unconsolidated sands and ductile shales. This paper describes a novel approach to modeling hydraulic fractures that is effective in brittle and ductile formations.
We then move on to dealing with fracturing in tight gas reservoirs with Actual and Optimal Hydraulic-Fracture Design in a Tight Gas Reservoir. Designing hydraulic-fracture stimulations to optimize well productivity requires knowledge of several key parameters (such as the Young’s modulus and the Poisson’s ratio to name but two). If these are left unknown, the hydraulic-fracture stimulation is likely to be severely suboptimal. This paper integrates pressure-buildup and production transient analyses with microseismic surveys and the recorded pumping schedule to estimate such unknown parameters in previously fractured wells in a tight gas reservoir that have been on production for up to 8.5 years.
Our final topic covers artificial lift. Simulation and Testing of the Hydraulic Performance of the Sliding Vane Pump describes the development and testing of a new all-metal sliding-vane pump and matching lift system. This was developed as an alternative to low efficiency conventional artificial-lift systems that display poor temperature performance. Numerical simulation and laboratory tests were used to conduct a comparative study of the hydraulic performance of the pump.
We end this issue with a discussion of electrical submersible pumps (ESPs) in Nodal Analysis by Use of ESP Intake and Discharge Pressure Gauges. ESPs are often not only equipped with bottomhole-pressure gauges, but more frequently contain discharge pressure gauges as well. This combination of gauges can be used to extend the classical nodal-analysis approach with an extra component, which is described in detail in the paper.
I find that I’m always driven to say that I hope that you enjoy reading these papers as much as I enjoyed selecting them because for me this is so true. Additionally, I am delighted to congratulate Ian Walton, Max Shippen, and Pavel Bedrikovetsky on their appointment as SPE Distinguished Lecturers representing the production and operations community (more details of their lectures and schedules can be found at http://www.spe.org/dl/schedule.php). Nominations for the 2017–18 session are open through March 15th; however, the online portal is available year round at http://www.spe.org/dl/nominations.php.
Ian Collins, BP Exploration