--> --> Research on the Key Technologies of Liner Top Packer for HT/HP and High Acidic Oil and Gas Wells

Petroleum Drilling Techniques, Issue 5, 2018

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Research on the Key Technologies of Liner Top Packer for HT/HP and High Acidic Oil and Gas Wells

Abstract

The key technologies for the HT/HP and high corrosion resistance of the top packer liner have been studied pertinent to the problems of corrosion failure and even Sustained Casing Pressure (SCP) under the environment of HT/HP and high acidic oil and gas wells. According to the characteristics of each component of top packer liner and the performance requirements of such wells, a reasonable material selection was carried out, and the uniform corrosion, pitting, stress corrosion cracking and galvanic corrosion risks of the main metal materials were evaluated by immersion test, stress corrosion test and electrochemical test. Later, tests for temperature resistance, pressure resistance and corrosion resistance of selected rubber materials were conducted. The study found that 718 nickel-based alloy has good resistances to uniform corrosion, pitting and stress corrosion cracking, can be used as the main metal material of the packer. Further, 13Cr stainless steel and low alloy steel have a low galvanic corrosion rate while contacting with 718 nickel-based alloy, and they can be used as the main auxiliary material. The modified tetra propylene rubber material presents a mechanical performance retention rate of 90% or higher after placing into corrosive environments for 96h at temperature of 150℃, H2S partial pressure of 3. 5 MPa, CO2 partial pressure of 3. 0 MPa. The packer element processed with such rubber has good tight gas performance in highly corrosive acidic environments. The top packer liner manufactured with the above materials was tested in Well Yuanba 10-3. The test results show that such top packer liner is reliable, indicating the practical materials selection. This research suggests that the modified top packer liner is an effective means for solving the problems of SCP and similar problems existing in HT/HP and high acidic oil and gas wells.