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Collaborating Authors
Results
Fracture Characterization in Basement Using the Latest Generation of LWD Sonic and Resistivity Image Logs
Dac, The Nguyen (Schlumberger) | Thien, Kim Nguyen P. (Schlumberger) | Le, Duy Cao (Cuu Long Joint Operating Company) | Tuan, Anh Truong (Cuu Long Joint Operating Company) | Dang, Khoa Chau (Cuu Long Joint Operating Company) | Ahmed, Aqil (Schlumberger) | Taesoo, Kim (Schlumberger) | Rehman, Sadu-ur (Schlumberger) | Thai, Ha Phung (Schlumberger) | Anh, Pho Le (Schlumberger)
Abstract Today, fractured basement is becoming an important contributor to the petroleum industry. However, drilling into the granitic basement reservoir is challenging because of the severe shocks and vibrations and the high requirement for accurate detection of productive fractures. Logging-while-drilling (LWD) technology has quickly adapted to respond to these challenges. The development of new LWD sonic and electric image tools supports an integrated methodology for reservoir characterization and fluid identification, which are critical for success. The new methodology takes advantage of the latest technology of LWD resistivity image logs and LWD sonic acquisition; the processed high-resolution resistivity images enable the identification of borehole breakouts, natural or induced fractures, vugs, and dips, and Stoneley measurements from the LWD sonic tool enable analysis of the producibility of fracture system with the sonic fracture technique. The integrated methodology combines the strength of the two independent methods to give a comprehensive characterization of the fracture systems. Analysis from LWD sonic and resistivity images provide location and characters of faults or fractures (open/closed). Results from the analysis are also important input for the production and perforation planning. The case history in this paper shows excellent results from the integrated fracture evaluation with LWD sonic and resistivity image logs. In this case study, fracture database for well design and field development is updated with the result obtained from the well. It is the first time of combining latest generation of LWD sonic and LWD resistivity imaging logs in Vietnam, essentially this sets a benchmark in the fractured basement characterization. Numerous basement reservoirs are present in Vietnam and worldwide. This advanced technology opens opportunities for fracture evaluation in basement reservoirs using LWD technology.
- Asia > Vietnam (0.56)
- North America > United States > Texas (0.29)
Combining Sonic While Drilling and Formation Pressure While Drilling for Pore Pressure Analysis to Reduce Drilling Risk: A Case Study in Offshore Vietnam
Dac, The Nguyen (Schlumberger) | My, Dung Doan Thi (Schlumberger) | Ahmed, Aqil (Schlumberger) | Thai, Ha Phung (Schlumberger) | Rehman, Sadu-ur (Schlumberger) | Truong, Son Nguyen (Bien Dong Petroleum Operating Company) | Hong, Giang Khuc (Bien Dong Petroleum Operating Company)
Abstract The accurate prediction of pore pressure is important for safe drilling and can reduce financial risk significantly. The major focus during drilling in a high-temperature/high-pressure (HP/HT) environment is optimizing the drilling operation to mitigate risk by utilizing data such as sonic logging-while-drilling (LWD) and offset well information. An offshore exploration well was being drilled in offshore Vietnam with drilling challenges of abnormally high formation pressure. In normally compacting sediments, water escapes through permeable sands or along fractures as overburden sediments build up, and fluid or pore pressure remains close to hydrostatic pressure. In such normally compacting sediments, under increasing effective pressure, porosity decreases and compressional velocity increases. However, if formation fluids cannot escape, for example due to the low permeability of overlying shales, then they bear part of the overburden load and hence become overpressured. These formations are called undercompacted, meaning they have a higher porosity than normally compacted shales. In overpressured shales, which contain pressured water, density is lower, porosity is higher, and compressional velocity is lower than normal. Formation pressure can be the major factor affecting the success of drilling operations. If pressure is not properly evaluated, it can lead to drilling problems such as lost circulation, kick, stuck pipe, hole instability, and excessive costs. Therefore, knowledge of the pore pressure is of considerable value because it provides the means for improving drilling operations and designing better casing programs to reduce those risks. Using the data gathered from well logs, it is possible to predict the probable pressure profile that will be encountered while drilling. LWD data enable monitoring pore pressure very effectively; this pore pressure prediction can be continuously updated using LWD sonic and formation pressure while drilling (FPWD) to make optimal decisions for drilling operation. Once a suitable predrill pressure profile is established, it is monitored on the current wells with while drilling sonic and directly calibrated with formation pressures taken in sands. In the offshore Vietnam well, pore pressure monitoring by LWD formation pressures and estimated pore pressure from LWD sonic data allowed drilling operations to be optimized. Employing this technique led to successful drilling without any incidences related to pore pressure. The computed pressures from LWD sonic matched the measured pressures obtained from FPWD. The real-time sonic matched the recorded-mode sonic closely. This technique could apply not only to the wells in this basin but also to the other wells in the locations with abnormal high formation pressure.
- Asia > Vietnam (0.92)
- North America > United States > Texas (0.30)
- Europe > Norway > Norwegian Sea (0.24)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.65)