Production and Characterization of High Solid Content Cellulose Nanofibrils from Pretreated Fluff Pulp

The increasing demand for cellulose nanofibrils (CNF) necessitates the development of novel processes to produce high-solid content and consistent quality nanofibrils. In this study, we investigated the combination of mechanical and chemical pretreatment methods (carboxymethylcellulose, CMC dispersion, and sodium hydroxide, NaOH swelling with ball milling) for cellulose fibers followed by high-pressure homogenization to evaluate the CNF characteristics. The carboxymethylcellulose (CMC) dispersion with 75 min ball milling and NaOH swelling with 15, 45, and 75 min ball milling of cellulose slurry reduced the fiber dimensions by up to 90% that eased the fibrillation to produce about 6% solid content CNF during high-pressure homogenization. The characterization of CNF hydrogels produced from pretreated samples revealed that they had an average fibril width of less than 30 nm with good dispersion stability. The CMC dispersion and NaOH swelling with ball milling of cellulose slurry did not significantly affect the chemical structure and the crystallinity of CNF hydrogels. On the other hand, the tensile strength of all the pretreated CNF samples was increased up to 105±14 MPa when compared with that of the control sample (58±6 MPa). NaOH treatment has slightly increased the thermal stability of CNF samples over CMC treated and control samples. In conclusion, short fibers generated by mild alkaline pretreatment with ball milling followed by high-pressure homogenization of cellulose fibers can produce the consistent quality CNF with high solid content and tensile strengths for various industrial applications.

Extreme Well Electrical Submersible Pump: Altering Perception in Artificial Lift Selection

Electrical Submersible Pump (ESP) is an artificial lift that often associated with big production rate, which is at least 300 bbls/day. ESP also has limitation in handling unconsolidated sand reservoir, high GOR wells, and minimum casing ID. As technology flourished, these handicaps for an ESP well are no longer valid. A breakthrough was established for ESP utilization. However people's perception of ESP persists. Extreme well ESP is changing that perception. There are three types of extreme well ESP: high solid content, high GOR, and slim-line ESP. High solid content ESP has open impellers. This type of impeller creates no space between impeller and diffuser, hence no solids accumulation. Multiphase pump (MPP) is used to handle high GOR problem. MPP stage design has axial screw type impeller and gas handling diffuser. Gas from reservoir fluid will be compressed and broken into smaller bubbles resulting in homogenous gas-liquid mixture, hence no gas lock during production. For well with small casing ID e.g., 4-1/2" casing, slim-line ESP with 3.19" outside diameter is utilized. These three types of extreme well ESP were all utilized in Central Sumatera Asset of Pertamina EP. High solid content ESPs were installed in five wells (MJ-134, MJ-132, MJ-128, STT-25, and KTT-23) in four different structures with production range of 30 to 1200 bbls/day. Basic Sediment (BS) number in this asset varies from 0.1% up to 40%, which results in suspending wells and repeating well services. In wells MJ-134, high solid content ESP was able to produce up to 50% BS number at the beginning of production. It showed excellent lifting capability in severe sand problem condition. While in wells STT-25 and KTT-23, utilizing high solid content ESP increases well's lifetime and generates gain in production. High GOR ESPs were installed in wells PPS-01 and SGC-15. Both wells has around 2000 scf/stb GOR. Conventional ESP would have a hard time producing these gassy wells. By using MPP, well PPS-01 produced smoothly and even later optimized to have bigger production. Producing well SGC-15 faced another handicap in form of scale deposition. Scale preventer was also installed for this well. Slim-line ESP was installed in well BJG-01 that has 4-1/2" casing. Grossing up the wells with slim-line ESP contributes production gain. Since October 2019 this project has produced cumulative production of 56,199 bbls oil and counting, and been considered successful in solving extreme well problems. Being proven able to handle high BS number, high GOR, and produce well with small casing size, extreme well ESP is altering old mindset in ESP utilization. All of handicaps mentioned above were redeemed obsolete. This breakthrough starts the dawn of new perception in artificial lift selection.

Fabrication of Energetic Composites with 91% Solid Content by 3D Direct Writing

Direct writing is a rapidly developing manufacturing technology that is convenient, adaptable and automated. It has been used in energetic composites to manufacture complex structures, improve product safety, and reduce waste. This work is aimed at probing the formability properties and combustion performances of aluminum/ammonium perchlorate with a high solid content for direct writing fabrication. Four kinds of samples with different solid content were successfully printed by adjusting printing parameters and inks formulas with excellent rheological behavior and combustion properties. A high solid content of 91% was manufactured and facile processed into complex structures. Micromorphology, rheology, density, burning rate, heat of combustion and combustion performance were evaluated to characterized four kinds of samples. As the solid content increases, the density, burning rate and heat of combustion are greatly enhanced. Based on 3D direct writing technology, complex energetic 3D structures with 91% solid content are shaped easier and more flexibly than in traditional manufacturing process, which provides a novel way for the manufacture of complicated structures of energetic components.