Research Of 7" Casing Valve Technology In Liaohe Oil Field

Liaohe Oilfield is the largest heavy oil base in China and is rich in heavy oil. With the exploitation over the years, the reducing reservoir pressure and the complicated structure of the buried hill strata, there exist great difficulties in the reservoir protection and the optimal fast safe drilling. In recent years, the conventional underbalanced drilling has been widely used in Liaohe Oilfield. However, short of the whole-process underbalanced drilling, reservoir damage is still serious. On the basis of previous researches, in view of the formation and well bore structure of Liaohe Oilfield, this paper probes into the casing valve technology of the whole-process of underbalanced drilling.The 9-5/8 " casing valve, independently developed by the author in 2012, has been tested in the field and its performance index has reached the level of similar products at home and abroad. With the demand of the whole-process underbalanced drilling, the paper carries out the research of the 7" casing valve technology and tries to improve the casing valve technology of the whole-process underbalanced drilling.By analyzing the well bore structure of Liaohe Oilfield, the paper has completed the downhole assembly structure design of the 7" casing valve and the assembly design of valve seal, finished the research of the valve plate actuating torsional spring and the measuring principle, and fulfilled the structure design of the measurement device and prototype development. Besides, the valve seal test, the valve plate switch validity test and the valve plate parameter measurement test are all carried out inside. The prototype has been tested comprehensively and the performance index has reached the requirements of the design and field test. Then according to the specific location, the corresponding parameters will be obtained and the field test scheme will be designed, so as to optimize drilling.