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2009年,泰国PTTEP公司在伊朗北部SIALK-1井小井眼裸眼井段钻遇高压气层时发生井漏,在堵漏期间又发生卡钻,随后环空发生溢流,关井后套管和钻杆内最高压力达到6800psi。期间多次从环空用7600psi压力强行压井失败,环空压力保持在5000psi左右。由于钻具与环空不相通,不能在钻具和环空之间建立有效的循环,因此通过常规方法已经不能压井。经过PTTEP专家组讨论,决定采用连续油管技术压井,从3.5in钻杆内(内径2.44in)下入带有独立封井器(10000psi)的1/34in连续油管来替换钻杆内被污染的泥浆,在连续油管内和钻杆之间建立钻井液循环,然后在3.5in钻杆内对卡点进行电缆爆炸松扣,从而建立钻具和环空之间的循环,达到钻井液平衡压井。利用连续油管在小井眼高压井段压井的关键是必须采用高压防喷器,防止钻具内压力突然释放而井口失控,同时使用地面节流阀控制出口压力。安装连续油管前必须先在连续油管头安装喷嘴,反复清洗油管内部,保持油管通畅;同时必须对连续油管及接头进行拉力测试。在连续油管下入钻杆过程中,必须控制进、出口压力,控制下钻速度,通过高压泥浆泵将钻具内污染的泥浆全部替换出来,建立连续油管和钻杆之间的循环。
In 2009, PTTEP of Thailand suffered a loss of circulation when it encountered a high-pressure gas zone in the slimhole of SIALK-1 well in northern Iran. In addition, a stuck pipe was stuck during the plugging and overflow occurred in the annulus. After casing shut-in and The highest pressure in the drill pipe reaches 6800psi. Many times from the annulus with 7600psi pressure forced killing failure, annulus pressure remained at about 5000psi. Because the drill does not communicate with the annulus and can not establish an effective circulation between the drill and the annulus, it is no longer possible to kill the well by conventional methods. After PTTEP expert group discussions, it was decided to use coiled tubing to kill the contaminated drill pipe from a 3.5 in. Drill pipe (2.44 in id) into a 1/34 in. Coiled tubing with a separate blocker (10,000 psi) Mud, drilling fluid circulation is established between the coiled tubing and the drill pipe, and then cable detonation of the snap point within the 3.5-inch drill pipe to establish the loop between the drill and the annulus to reach the drilling fluid balance kill . The key to using coiled tubing to kill a well in a high-pressure well section of a slimhole is to use a high-pressure blowout preventer to prevent a sudden release of pressure within the drill while leaving the wellhead out of control and a ground throttling valve to control outlet pressure. Before installing coiled tubing, nozzles must be installed on the coiled tubing head to clean the tubing repeatedly and keep the tubing open. At the same time, the coiled tubing and fittings must be tested for tensile strength. In the coiled tubing into the drill pipe process, you must control the inlet and outlet pressure, control the drilling speed, through the high pressure mud pump to replace all contaminated mud within the drill to establish a coiled tubing and drill pipe between the cycle.