【正文】 having a pipe handling system, spinning wrench and torque wrench, pipe slips, and even functioning as a mud bucket. The rig has provisions for all of these operations, either manual or automated. It was found in operation that the rig crew had difficulty in changing their work flow to use the newly bined functionality. In the new continuous circulation sub,and existing circulation subs, the crew uses all the same equipment they are trained to use. This provides an improvement in efficiency and connection using a continuous circulation chamber, the connection process was essentially concealed. With continuous circulation subs, however, the drill crew can see every part of the process. The slips 4 are set, the system is extended to engage the sub, a green strobe light or similar visual indicator signals that the barrier has passed its pressure check, and then the iron roughneck is used to break the connection directly above the new continuous circulation sub. In this case the roughnecks are very much a part of the connection process, and have a direct impact on the speed of the connection. It is expected that the new continuous circulation sub will take roughly one minute to engage the pipe, insert the ball, and perform the barrier integrity check. The same or less time will be taken when removing the ball. With a predicted five minute or less connection time, MPD is being much more efficient. This is a very significant leap forward for MPD. Initial Testing Certain elements of the design have been developed based on the results of testing. The replaceable barrier has been tested using a flow fixture with various arrangments of valves to simulate the rig’s stand pipe manifold. The flow fixture was transparent where the ball enters the sub and seals. Water is flowed through the setup to simulate very thin drilling mud. The timing of the valves opening and closing plays a role in how efficiently the ball is shifted into the circulation sub. It was a challenge to reduce the number of valves to a minimum, but also provide doublevalveprotection at all times. Figure 1 shows the typical valve schematic for the new continuous circulation sub. During testing it was found that the ball can be shifted with very little pressure differential and that velocity appears to be the largest influence on the operation. Once seated the pressure differential required to generate a seal is also negligible. Another development was the position and shape of the internal geometry, such that the ball is encouraged to travel “up” into the sub, even at very low transition speeds. A pressure gage on the downstream side of the sub registered almost no pressure changes during shifting of the ball. This is primarily due to the flow area never being restricted throughout the shifting sequence. The ball material was also experiemented with, and the initial testing was done with a rubber coated steel core. The significant weight of the ball posed no issue with being transferred using almost no pressure differential. Another area of interest was the clearance between the internals of the continuous circulation sub and the associated plumbing with respect to the ball. This ball must be transported efficiently within these pipes for a short distance, so the leakage cannot be excessive. The clearance didn’t prove to be as much concern as expected, even when using low viscosity fluids and much larger than practical clearances. The system is also very intuitive。 one provides pressure and flow from the mud pumps,and the other is primarily a vent line. By having two high pressure access points to the connection, it is possible to have a “safe” pressure differential. If a leak is detected, the process can be reversed and attempted again. In the new continuous circulation sub, the ball can be returned to the valve system and reinserted, or simply replaced. Because the ball is a selfaligning seal mechanism, it is very difficult to see a nonsealing situation. If difficulty is seen when seating the ball, the dynamics of the pressure differential can be tuned to provide a more positive “hammer” when it seats, or a stronger application of pressure differential. Additionally, the low cost of the ball encourages the precautionary measure of changing it for each connection. Many material choices are available which can cope with the specific mud conditions experienced。 本 科 畢 業(yè) 論 文（ 翻 譯 ） 英文標(biāo)題 Continuous circulation drillingsystem 學(xué)生姓名 學(xué) 號 教學(xué)院系 專業(yè)年級 指導(dǎo)教師 職 稱 單 位 輔導(dǎo)教師 職 稱 單 位 完成日期 2022 年 04 月 1 Continuous Circulation Drill String Sub Abstract There is an increasing need to drill difficult reservoirs in a cost effective way. Over the past few years Managed Pressure Drilling (MPD) has made it possible to drill reservoirs which have a narrow window between pore and fracture pressure gradients. Before the introduction of MPD techniques, safely drilling and pleting these formations was very costly and not always successful. Cycling the mud pumps off and on for connections affects the pressure and is a major problem for and equipment have been developed to make a connection while continuing to circulate the drilling mud to maintain constant pressure. Since 2022, the Continuous Circulation System (CCS) has allowed continuous circulation during connections with traditional jointed drill pipe, by using a chamber around the connection. Several panies have developed continuous circulation subs which are threaded between tool joints to achieve continuous circulation without a pressure chamber. These have had varying degrees of success from both an operational and safety standpoint. This paper describes the current MPD market and describes the philosophy adopted for a new sideentry sub.