China
Africa
Explore chapters and articles related to this topic
Offshore Drilling
Published in Sukumar Laik, Offshore Petroleum Drilling and Production, 2018
In the case of a surface wellhead used either on land or at the deck of a platform, it comprises casing heads, casing hangers and tubing head, and tubing hanger along with sealing elements. Figure 4.65 shows a typical surface wellhead assembly consisting of different casing heads joined one above the other and the casing hangers seat in the bowl of the casing head to hang or suspend the next smaller casing string securely and provide a seal between the suspended casing and the casing head bowl. Similarly, the tubing head is a housing, attached to the top flange on the uppermost casing head to provide a support for the tubing through a tubing hanger which also provides a seal between the tubing and the tubing head. Thus, it is found that as the casings are lowered, they are landed from different hangers by connecting different casing heads one above the other.
Fossil Energy Sources
Published in Anco S. Blazev, Power Generation and the Environment, 2021
The wellhead consists of three components: the casing head, which consists of heavy fittings that provide a seal between the casing and the surface; the tubing head, which provides a seal between the tubing, which is run inside the casing and the surface; and the Christmas tree, which is the piece of equipment that fits on top of the casing and tubing heads, and contains tubes and valves that control the flow of hydrocarbons and other fluids out of the well.
Pressure survey, analysis and diagnostic of small diameter velocity string to improve well monitoring and surveillance
Published in Petroleum Science and Technology, 2023
Zhong Bo Zhai, Shi Wei Qi, Gayatri Kartoatmodjo
The L well block is in the southern margin of the Ordos Basin in China which is in the natural gas enrichment area, and belongs to a tight gas reservoir. After a natural gas well has been produced for a period, the formation pressure near the wellbore gradually decreases, and the production drawdown decreases immediately, resulting in a decrease in gas production. When the gas rate is lower than the critical gas rate, natural gas cannot carry liquid normally, causing droplets to accumulate in the bottom hole, increasing the bottom hole flowing pressure, and ultimately reducing the gas production, causing liquid accumulation or even water loading in the gas well, and the gas well cannot produce normally (Turner, Hubbard, and Dukler 1969, Min, Ping, and Guangtian 2001 and Tugan 2020). The most frequently utilized gas well deliquification methods include: foam agent injection (assist the gas lift with the help of low-density water-bearing foam) (Ana et al. 2019), velocity string (reduce the critical gas rate) (Alec and John 1998) and plunger gas lift (reduce the liquid slippage with the plunger) (Acosta, Pereyra, and Sarica 2018). The completion of some wells in L well block does not have annulus, the casing head pressure cannot be monitored, and deliquification (liquid unloading or dewatering) measures such as foam agent injection or plunger gas lift cannot be used, which have certain limitations. As a common deliquification measure, velocity string has the advantages of no well-killing operation, low reservoir damage, predictability, positive economics, and quick response (Zhongbo et al. 2021b, Binbin et al. 2012, Haoru and Dongyu 2020), and it is widely used.
Investigation of the effectiveness of velocity string to improve gas well productivity
Published in Petroleum Science and Technology, 2022
Zhongbo Zhai, Shiwei Qi, Gayatri Kartoatmodjo, Taiji Wang, Junfeng Wang, Jiangwei Bo
The wells are completed in single completion with either deviated or horizontal completion. Partial production strings of directional wells are: outer diameter 88.9 mm (inner diameter 74.2 mm) tubing, and horizontal wells adopt upper OD 88.9 mm (ID 74.2 mm) + lower OD 114.3 mm (ID 99.6 mm) casing as production strings combination. However, these production string structures above have no annulus, therefore it has application limitations. It cannot monitor the casing head pressure and cannot implement de-liquification measures such as foam agent injection through annulus, plunger lift or nitrogen gas lift, etc.