Minimum Structure for Well Appraisal in Marginal Fields at 35m Water Depth without Jacket & Mudline Suspension System

ABSTRACT This paper proposes a minimum structure for drilling two appraisal wells. Conductors will be driven into seabed by a crane vessel or drilling-rig crane through a pre-installed lightweight guide-frame placed on seabed. After driving the conductors to required depth, the frame is raised and joined to the conductors at appropriate elevation by bolted and grouted connections. Six tie members connected between the frame and seabed by specially-designed small mat foundations will ensure stability of the structure against environmental loads. A small deck will be installed on the top of conductors to provide space for essential equipment required for prolonged well testing after departure of drilling rig. The platform will be accessed by small boats through a boat landing and ladder. In case of positive drilling outcome, a riser and flexible pipeline will be added to connect with the nearest subsea tie-in point. A detailed structural design of the minimum facility is performed to withstand omnidirectional environmental loads due to 10.0m high wave along with associated wind and current loads. Susceptibility of the structure against dynamic effect of wave loads is also investigated. Demonstration of structural adequacy against wave-induced fatigue loads and reserve strength against extreme environmental loads show the robustness of the minimum structure to perform against design environmental loads.

Pengembangan Sistem Pemantauan dan Deteksi Serangan pada Ekosistem Rumah Cerdas

It is predicted that the growth of smart devices installed in the smart home ecosystem will increase in the future. Smart devices that are connected to each other using wired or wireless networks that have the potential for security holes are attacked by threat actors. Whereas a house is a place that provides comfort for its residents. An attack on the smart home ecosystem allows the operation of the smart home ecosystem to be disrupted or personal information stolen to be used by irresponsible parties. To face the high wave of smart home implementation in the future with potential security holes that always accompany it. This is in accordance with the principle that no system is 100% secure. In this study, attacks on wireless networks can be detected as anomalous traffic. Monitoring and detection in the smart home ecosystem involves supporting components such as sensors, access points, gateway collectors and analysis stacks.

Hidrodinamika Gelombang pada Terumbu Karang di Pulau Panjang, Jepara

Posisi Pulau Panjang berada di sisi barat garis pantai pesisir kota Jepara, menjadikannya sebagai penghalang (barrier) terhadap gelombang yang akan menghantam pesisir Jepara. Pulau Panjang dikelilingi oleh gugusan terumbu karang. Keterpaparan (exposure) terumbu karang oleh hidrodinamika gelombang yang melewatinya perlu dikaji. Oleh sebab itu, dibutuhkan penelitian mengenai hidrodinamika gelombang pada terumbu karang di perairan Pulau Panjang. Hasil penelitian didapatkan bahwa nilai gelombang yaitu gelombang signifikan (Hs), periode gelombang signifikan (Ts) adalah bervariasi. Nilai gelombang (Hs dan Hs) tinggi, akan mengakibatkan terumbu karang pada sisi barat, timur laut dan tenggara Pulau Panjang lebih menerima keterpaparan (ekposure) oleh hidrodinamika gelombang yang melewatinya. Pada hidrodinamika gelombang lebih rendah, maka terumbu karang yang terlindung dari keterpaparan (ekposure) gelombang adalah yang berada pada sisi timur, barat daya, dan barat laut. Hasil interpolasi (Krigging) didapatkan hasil nilai Hs tertinggi berkisar antara 0,503-1,00. Arah datang gelombang dominan dari timur pulau Panjang, kemudian setelah melewati terumbu karang ada di sisi timur ,timur laut, dan utara Pulau Panjang maka energinya menjadi berkurang, sehingga terumbu karang yang ada di sisi barat, barat daya, dan selatan dari Pulau Panjang posisinya lebih aman dari keterpaparan (ekposure) oleh hidrodinamika gelombang yang melewatinya. Gelombang yang datang akan mengalami perubahan karakteristik (panjang, periode, tinggi gelombang) setelah melewati terumbu karang, sehingga gelombang yang menuju pantai akan semakin berkurang seiring dengan perubahan kedalaman. Tingkat keterpaparan (ekposure) terumbu karang yang ada pada sisi timur,timur laut dan utara di Pulau Panjang oleh gelombang cukup tinggi, hal ini diduga yang menjadi salah satu faktor penyebab kerusakan terumbu karang yang ada diperairan Pulau Panjang. The position of Pulau Panjang is on the west side of the coastal coastline of the city of Jepara, making it a barrier against waves that will hit the coast of Jepara. Panjang Island is surrounded by clusters of coral reefs. The exposure (exposure) of coral reefs by the hydrodynamics of the waves that pass through them needs to be studied. The modeling results are then generated into a shapefile map to be overlaid with a shapefile map of changes in coral reefs by interpolation method with Kriging block. The results showed that the wave value, namely the significant wave (Hs), the period of the significant wave (Ts) varied. High wave values (Hs and Hs) will result in coral reefs on the west, northeast, and southeast sides of Panjang Island receiving more exposure (exposure) by the hydrodynamics of the waves that pass through them. At lower wave hydrodynamics, the coral reefs that are protected from wave exposure are those on the east, southwest, and northwest sides. The results of interpolation (Kriging) obtained the highest Hs values ranging from 0.503 to 1.00. The direction of the dominant wave coming from the east of Panjang Island, then after passing through the coral reefs is on the east, northeast, and north of Panjang Island, the energy is reduced, so that the coral reefs on the west, southwest, and south sides of Panjang Island are safer from exposure (exposure) by the hydrodynamics of waves that pass through it. The incoming waves will experience changes in characteristics (length, period, wave height) after passing through the coral reef so that the waves towards the coast will decrease along with changes in depth. The level of exposure to coral reefs on the east, northeast, and north sides of Panjang Island by waves is quite high, this is thought to be one of the factors causing damage to coral reefs in the waters of Panjang Island.

Microplastic pollution on island beaches, Oahu, Hawai`i

We report microplastic densities on windward beaches of Oahu, Hawai`i, USA, an island that received about 6 million tourist visits a year. Microplastic densities, surveyed on six Oahu beaches, were highest on the beaches with the coarsest sands, associated with high wave energy. On those beaches, densities were very high (700–1700 particles m-2), as high as those recorded on other remote island beaches worldwide. Densities were higher at storm tide lines than high tide lines. Results from our study provide empirical data on the distribution of microplastics on the most populated and visited of the Hawaiian islands.

An exceptionally high wave at the CNR-ISMAR oceanographic tower in the Northern Adriatic Sea

On December 15, 2009, a very high wave crest was recorded by a local camera at the CNR-ISMAR oceanographic tower, 15 km offshore Venice in the Northern Adriatic Sea (Italy). The height of the estimated crest elevation appears well beyond the value (1,25·Hs) commonly used to identify a wave as freak. We document the wave event with a full description of the corresponding met-ocean conditions and related measurements, of which we provide a critical analysis.

Investigation typhoon induced storm surge and high wave in Vietnam using coupled Delft3d-FLOW – WAVE models combined with weather research forecast (WRF) output wind field

Introduction: Typhoon-induced disasters including storm surge and high wave are obvious threats to coastal areas in Vietnam. Thus, many researchers have paid their attention to this issue. The approaching methods are varied, including statistical methods and also numerical methods. This study suggests the coupled models Delft3D-FLOW and WAVE, using the meteorological output data from the Weather Research Forecast (WRF) for investigating the typhoon induced disasters in the coastal areas in Viet Nam. Method: WRF is run in multiple domains with different grid resolutions simultaneously and there is an interaction between them to reproduce the wind field during the typhoon events. Delft3D-FLOW is coupled with Delft3D-WAVE (SWAN) through a dynamic interaction, in which the FLOW module considers the received radiation stresses calculated by the wave module. On the other side, the updated water depth including the contribution of the storm surge will be used by the WAVE module. Both Delft3D-FLOW and Delft3D-WAVE models used wind fields from the WRF simulation output as the meteorological input data. The total surge level includes the storm surge, wave-induced setup and the tidal level. Results: The case of extreme weather event Typhoon Kaemi (2000) was used to validate the wind field and the wave height. The calibration process of the the storm surge level was based on the observed data during Typhoon Xangsane (2006), while Typhoon Durian (2006) were used to validate the coupled models. The comparisons show the good agreement between simulated results and observed data, especially in terms of the peak water level and highest significant wave height, which mainly governed by the typhoon wind field. The simulated results reveal that the surge height durring Typhoon Durrian period along its path was ranged from 1.2 to more than 1.4m, which can be considered to pose the greatest risk to low-lying coastal areas of the Mekong Delta. Conclusion: The suggested coupled models can be used to investigate the impact of typhoon induced disasters.