Organic artificial synapses are becoming the most desirable format for neuromorphic computing due to their highly tunable resistive states. However, repressively low analog switching range, inferior memory retention, and operational instability greatly hinder the further development of organic synapses. Herein, two donor-acceptor copolymers consisting of electrondeficient isoindigo coupled with variable donating moieties for three-terminal organic synaptic transistors (TOSTs) are reported. It is found that the synaptic function and device stability of TOSTs are significantly improved by enhancing the electron-donating strength of donor units. Polymer alkylated isoindigo-bisethylenedioxythiophene exhibits high analog switching range of 170 ×, two orders of magnitude higher than that of normal organic neuromorphic devices. They also demonstrate excellent memory retention of over 5 × 10 3 s, low switching energy of 13 fJ, and ultrahigh operational stability with 99% of its original current after 100 000 write-read events in air. Furthermore, the high viability of strong donor strategy is showcased by demonstrating flexible TOSTs with stable synaptic function after repeated mechanical bending as well as organic synapses capable of simulating image information processing. Overall, this work highlights the advantages of the strong donor functionalization strategy to boost the synaptic performance and device stability of TOSTs.

No abstract

The Middle Bakken reservoir is considered an unconventional play because the reservoir is relatively thin and tight. The reservoir also depends on hydraulic fracturing in laterally drilled wells to free commercial quantities of oil. The available 3-D seismic in the study area shows the reservoir to be seismically thin (i.e. below seismic resolution at the frequencies recorded). Additionally, the complex fracture network created by hydraulic fracturing contributing to the oil production cannot be measured by the existing 3-D seismic data that was acquired before the drilling and hydraulic fracturing took place. Analysis in one 3-D seismic survey in the North Dakota Middle Bakken play recognized 16 seismic attributes from 99 extracted that showed some degree of correlation with cumulative productions from 19 Middle Bakken H1 lateral wells within the seismic survey area. After statistical variable selection methods were employed, only one seismic attribute (relative acoustic impedance) was found to have statistical significance to productivity. Identical analyses were employed using available geologic attributes to correlate to IP90, as well as correlating IP90 to a combination of seismic and geologic attributes. This paper presents a seismic attribute based statistical methodology that has been used for productivity analysis, without the necessity of precisely knowing the mechanism, in the Hawkeye / Blue Buttes field area in the Middle Bakken reservoir in North Dakota. Examples of productivity analyses will be shown using seismic attributes and seismic attributes plus regional geology attributes.

Fiberglass rods are mainly used to overcome the design limitations of rod pump equipment when additional lift capacity is required. Economic analyses for new installations or repair jobs must consider the life span of fiberglass rods. This study evaluates the cost-effectiveness of fiberglass rod applications by reviewing their life spans in the Permian Basin. The objective of this project was to build a stress fatigue diagram to help minimize expenses by maximizing the effective life of fiberglass rods. In theory, this diagram would define the allowable stress range that could be applied to fiberglass rods without causing excessive failures. Each data point would consist of one fiberglass rod failure, and all calculations would be performed over the age of the taper, from initial installation to failure. These operating limits would then be applied to field applications. The industry's rule of thumb for the "end of life" for fiberglass rods is 30-40 million rod reversals. However, most failures occurred before the rods reached one-third of their life expectancy, even though the fiberglass rods were operated well within the recommended stress ranges provided by the manufacturers. There was a positive relationship between average fiberglass taper failure frequency and average peak polished rod stress. Failures mainly occurred in the steel connection in the pin. Therefore, failures were not due to tensile stress fatigue in the fiberglass body. Failure frequency was so high in some fields that upsizing the pumping unit made more economic sense than installing a fiberglass taper. The recommendations from this project were to: (1) understand connection failures better through improved root cause failure analysis (RCFA) data collection and manufacturer involvement; (2) reassess and improve operational conditions at failure, such as rod pump design, pump off setpoints, and pump fillage; (3) evaluate switching to a 100% metal string with an upsized pumping unit or installing a different artificial lift method if failure frequency is not reduced by operational changes; and (4) re-evaluate rod string design criteria to maximize value, as current designs are based on tensile loading in the body of the top rod, but actual failures were not due to tensile stress fatigue in the body. Significant cost savings can be achieved if the average life span can be increased to the industry standard of 30-40 million rod reversals. More work needs to be done to understand connection failures.