Technology and Applications of Foam Drilling Fluid in Fractured and Complex Formations
Petroleum Science and Technology (Impact Factor: 0.31). 06/2012; 30(16):1747-1754. DOI: 10.1080/10916466.2011.606254
Fractured and complex formations where types of fractured and porous mud loss occurred in commonly induced instability of wellbore and drilling accidents such as borehole collapse and blowout; therefore, it is the technological bottleneck for the development of oil and gas. Solid free recyclable foam drilling fluid was developed and aimed to deal with the MIS oilfield of Iran, which has abnormally low pressure and developed fracture-cave hydrocarbon reservoir with a high concentration of H2S, which has problems such as serious lost circulation and H2S risk. A sectionalized drilling fluid system has been adopted in this oilfield, and drilling with water can meet the operation requirements during first spud and saturated salt polymer system or undersaturated salt polymer in second spud; the horizontal section adopts solid free recyclable foam drilling fluid to achieve near balance drilling and effectively solves the lost circulation problem in fractured limestone formation. The spot application indicates that solid free recyclable foam drilling fluid has excellent rheology, and meets the requirement of drilling engineering. Meanwhile, the system can retard the H2S corrosion effect on drillstring and guarantee to provide a good MWD transmission signal. A new idea has been provided for drilling engineering in fractured and complex formations.
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ABSTRACT: Using shut-in procedures is one of the oil-well-control measures to curtail kicks and prevent a blowout from occurring. Shut-in procedures are the specific procedures for closing a well in the case of a kick. If the well is not shut-in immediately after a kick is observed then a blowout will very likely happen. There are generally two types of shut-in procedures, which are soft shut-in and hard shut-in. Of these two methods, the hard shut-in is the fastest method to shut in the well; therefore, it will minimize the volume of kick allowed into the wellbore. The drawback of the hard shut-in is that it may result in the water hammer pressure on the capping hookup to increase and therefore damage the BOP (blowout preventer). In this work two devices were designed, one is for testing the water hammer pressure, and the other is for assessing the damage to the BOP caused by the hard shut-in. The experiments show that a hard shut-in can shut the well in a very short time, but it can cause obvious water hammer damage. By simulating the gas drilling process, it can be seen that the hard shut-in also causes obvious damage to the ram rubber of the BOP, which will reduce the seal reliability and may cause potential accidents.
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