Electrical Compact Modeling of SiGe Phototransistor: Impact of the Distributed Nature on Dynamic Behavior

International audienc

Studying Affecting Factors in Geothermal Energy Production from Depleted Oil Fields of Onshore Sarawak, Malaysia

The main focus of this project was to study the feasibility of extracting geothermal energy from existing onshore oil fields located in the Baram basin, in northern Sarawak, Malaysia. This basin has a rich history of over 110 years of oil and gas exploration and production. The idea of repurposing depleted hydrocarbon fields for geothermal energy production is more interesting than conventional geothermal cases is owing to elimination of huge drilling and completion costs. Geothermal energy is clean, continuous, reliable, has low carbon emissions, requires minimal land use, and has lower material costs compared to other renewable sources. Additionally, it has minimal reliance on critical minerals. Recent published data demonstrate that the global levelized cost of electricity (LCoE) for geothermal is competitive with other forms of renewables at around US$100 / MWh. At the time of writing, there are no operational geothermal power plants in Malaysia, but plans are in place to investigate its potential further in Sabah and West Malaysia after 2025. Our study utilized simulation methods to calculate enthalpy production under certain assumptions. Numerical simulation modeling was conducted to perform sensitivity analysis on selected parameters, aiming to understand the effect of subsurface uncertainties on the range of geothermal energy production. These parameters include permeability, porosity, rock thermal conductivity, rock heat capacity, injection flow rate, injection temperature, and well spacing. The value of each parameter was calibrated based on existing published literature, and they were varied from maximum to minimum values against a base case scenario. The sensitivity analysis demonstrated that well spacing was the most significant parameter affecting the amount of geothermal energy production for the selected realizations and scenarios, which were based on analogue studies of the Baram Basin fields.</p

Evaluation of stimulated reservoir volume in laboratory hydraulic fracturing with oil, water and liquid carbon dioxide under microscopy using the fluorescence method

© 2017, Springer International Publishing AG. In shale gas industry, it is desired to develop new reservoir fracturing and enhanced gas recovery technologies to replace the conventional hydraulic fracturing (HF), in order to reduce water usage to guarantee the environmental sustainability and boost individual well production. As the goal of HF is to create high conductivity fracturing networks as flow paths for gas, it is necessary for HF to activate and connect existing natural fractures to generate large fractures network. The success or failure of HF often depends on the stimulated reservoir volume (SRV) which is characterized by the quantity and the quality of the fractures network resulted. This study investigates the micro-fractures network resulted in laboratory HF experiments in 2-D thin polished section by using a fluorescent method supported by advanced computerized image analysis. To evaluate difference of resulted SRV due to the difference of fracturing fluid, using three cylindrical shale cores and three granite cubes having fractures induced by HF using three fluids having different viscosity; oil, water and liquid carbon dioxide (L-CO2). The observation and statistical analysis of fractures induced in HF by the three different fluid viscosities using the fluorescent method showed ability of L-CO2 injection to achieve effective stimulation. The results suggest that employing a low viscosity fluid in HF of shale reservoirs can achieve more productive network with better SRV. In addition, the observation seems to be consistent with the tendency observed in the previous researches