Lower Layer Water Shut-off Technology For Layer System Adjustment

Polymer flooding technology is an important technology for sustainable development in the late high water cut period of the Daqing Oilfield, which is an effective measure to improve oil recovery further for Daqing Oilfield. With the end of good layers flooding, the flooding objectives are shifted to thin and poor layers; therefore, lower layer water shut off technology is needed for a large number of injection wells and oil layers. The technology is one of the associated technologies for polymer plooding, which is shutting off the lower flooded layers and then, producing the upper oil layers.Mechanical water shut-off technologies have been gradually improved since the development of the Daqing Oilfield.Till now, four catageries with 36 types of water shut-off strings have been formed, which meets the requirements of conventional water shut-off in the Daqing Oilfield. However, only the water shut-off string with drillable packers can meet the special requirements of hig working pressure and long service life(5~6 years in general) from the perspective of the characteristics of the water shut-off strings, performance indices and application. Tool cost and operation cost per well are still high in the field application, which limit the application scale. Meanwhile, milling period for some well is long and milling cost is high due to the effect of construction condition and equipment.Based on analyzing the performance, production and application of slip packer in and out of China, lower layer wate shut-off strings with reliable performance, long service life, low cost and simple technical process have been designed for special requirements of water shut-off in polymer flooding wells. Both the structure and principle of the string and associated tools are studied.Y443-108 drillable bridge plug, which is the main water shut-off tool, is put forward, in addition, down hole drillable bridge plug and associated tools have been designed. Meanwhile, the force analysis of Y443-108 drillable packer and the effect study of impact load to kinetic characters have been done. The design method of packing element and slips which are the key units for the drillable bridge plug has been done. By comparing the stress analysis of laboratory experiments, theoretical analysis and field application of the lower water shut-off strings, the validity of the design theory is conformed further.The design principle and calculation procedure for a series of Y443 drillable bridge plugs (packers) are sumed up in this thesis, which is helpful for string design on oilfield development, production and anchorage.