Nygaard, RunarYuan, Na2024-04-152024-04-152024-05-15https://hdl.handle.net/11244/340229The importance of downhole pressure sensing has risen significantly in oil and gas operations. Improvements in downhole sensing technology are expected to positively impact drilling, stimulation, production forecasting, and wellbore integrity. However, available downhole pressure sensors are expensive, have limited distribution capabilities, and have a short lifespan. To address these issues, a proposal has been made for an all-digital, low-cost downhole pressure sensor that can be permanently installed and distributed throughout a wellbore. This proposed sensor can measure pressure up to 10,000 psi (69 MPa) and has a temperature limit of 482°F (250°C). This study aims to design the pressure system, conduct laboratory testing to validate the sensor under downhole pressure and temperature conditions, and prepare for a field validation test of the sensor system. A literature review discusses and compares the latest technics of downhole pressure sensors. Different pressure sensor types, designs, and applications are discussed. After establishing a background study of the requirements for developing a new sensor, we do the modeling work of all the parts of the new sensor within the required ranges. Then, we have the laboratory test done in the simulated environment of up to 3,000 psi (21MPa) and 194°F (90°C). After that, we compared the result with the field test results and evaluated the sensor performance. Ultimately, we have the last laboratory test to test the multiplexing of five sensors with the 10,000 ft (3048 m) long cable, high temperature up to 536°F (280°C), and then test the sensor to fail. This integrated study helps to understand the downhole sensor, its history, the application, and the working mechanism, as well as how to make sensor selections with diverse downhole environments and operation requirements.permanent downhole pressure sensorunconventional oil and gas fieldsfinite element analysis