Stability and photodegradation studies of HDPE film blended with recycled HDPE, with and without pro-oxidant, were carried out by subjecting the film to accelerated UV exposure up to 144 hours. Two types of recycled HDPE were used; one containing pro-oxidant (recycled degradable HDPE-RDH) and the other without pro-oxidant (recycled standard HDPE-RSH). The loading levels of recycled HDPE were varied from 10 to 30% by weight. The degradation behaviour of the film was then evaluated based on elongation at break, carbonyl index and oxidative induction time (OIT). The results obtained show that the degradation rate of HDPE films, with different levels and types of recycled HDPE (RSH and RDH), were directly correlated to UV exposure time. However, more pronounced changes in elongation at break and carbonyl index were observed, in particular the HDPE film blended with RDH. At 30% loading of RDH, the film degraded at a higher rate compared with film containing the same level of RSH. This suggests that HDPE blended with RDH even at a low loading of 10% could promote degradation of the film. The remaining pro-oxidants in RDH induced the formation of free radicals in the HDPE chain and accelerated the degradation process.
Relevant to maximizing oil recovery, water injection is implemented for reservoir pressure maintenance and to maximize oil sweeping. The water injection involves both surface and subsurface matters. Since the objective is reservoir pressure maintenance and oil sweeping efficiency improvement, the subsurface domain includes reservoir engineering, geology and geophysics as well as the production technology. For surface operations, the water injection operation includes water injection source, water plant operations and water injection infrastructure. Water injection bottle neck and water quality issue may occur and damage the water injection efficiency. An idea of molecule to molecule (M2M) water injection performance review is raised to conduct a comprehensive and collaborative water injection review that involving many and outreach parties such as reservoir engineers, geologists, geophysicists, operation engineers, production chemists, production technologists, maintenance engineers, production planners and process engineers. The opportunity to include technical providers, partner representatives and host government representatives is taken in order to allow an effective discussion and quicken the maturing of relevant solution proposals. Comprehensive end to end review from the point of water source up to the point of producer is done to identify problem at each point, threats and improvement opportunities at every single node within the whole chain. With the M2M, water injection performance review has effectively provided an effective collaborative working environment as well as a learning avenue for young professionals that are involved in water injection matters. Many action items are resulted from the exercise and they are having high impact including safeguarding potential cost of USD 10 million per year for the water injection plant and infrastructure operations. In the short run, no disturbances for oil production and in the long run, the oil recovery can be maximized. Due to some limitation, this paper discusses only the surface water injection operations.
Water injection (WI) to improve oil production and increase reserves had been practiced in Malaysia since 1990s. Currently, around 27 fields are producing with water injection. To better manage these WI fields and gauge the relative performance of these fields, certain Key Performance Area (KPA) and Key Performance Indicators (KPI) were identified. Measurement of these KPA and KPIs serves as a yardstick to compare performance of WI fields and thus provide measures to improve collective performance by promoting replication of best practices and sharing lessons learnt. In the era of digital technology, the periodic measurement of KPA and KPI has been automated using the existing online platform which can remain accessible to all related parties. It provides a platform for data visualization with simple look forward analysis. The WI data is stored in company databank and the performance dashboard can be viewed from existing software. The team managed to overcome the challenges in completing the historical data gap and data hygiene which previously were managed manually and were not integrated. This resulted in historical evaluation of KPAs and KPIs of certain fields. This automation initiative will enable practicing engineers to identify the value leakages and proposed mitigation efforts. Some of the best practices identified such as pipeline pigging optimization, correct biocide dosage, periodic calibration of flow meter and chemical optimization already helped to reduce operating cost in certain WI fields. With these efforts, the company could reduce the operating cost significantly in year 2018. Other than data visualization, the tool provides diagnostic plots such as Hall Plot, Chan's Plot etc. for quick analysis of signs of well/ reservoir health deviations and thus solutions could be provided proactively. On seeing the initial positive results, this tool is being tried for the rest of the WI fields. This paper details how this tool tries to diagnose all sub-optimal areas within various WI project simultaneously, which leads to operational excellence and improvement in oil recovery, by identifying value leakages, providing proactive solutions with replication of thus identified best practices. Additionally, usage of this tool to rank WI performance of different projects can potentially help to initiate competition between different operators for improvement.
Injectivity formation damage with water-flooding using sea/produced water has been widely reported in the North Sea, the Gulf of Mexico and the Campos Basin in Brazil. The damage is due to the capture of solid/liquid particles by the rock with consequent permeability decline; it is also due to the formation of a low permeable external filter cake. Yet, moderate injectivity decline is not too damaging with long horizontal injectors where the initial injectivity is high. In this case, injection of raw or poorly treated water would save money on water treatment, which is not only cumbersome but also an expensive procedure in offshore projects. In this paper we investigate the effects of injected water quality on waterflooding using horizontal wells. It was found that induced injectivity damage results in increased sweep efficiency. The explanation of the phenomenon is as follows: injectivity rate is distributed along a horizontal well non-uniformly; water advances faster from higher rate intervals resulting in early breakthrough; the retained particles plug mostly the high permeability channels and homogenise the injectivity profile along the well. An analytical model for injectivity decline accounting for particle capture and a low permeable external filter cake formation has been implemented into the Eclipse 100 reservoir simulator. It is shown that sweep efficiency in a heterogeneous formation can increase by up to 5% after one pore volume injected, compared to clean water injection.
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