The high-speed gas flow in tubing causes erosion damage to the string for high pressure and high production gas wells,and the erosion threats the security of gas production and operation seriously.The tubing string with packers tends to be buckled,making the erosion more damaging,which is prone to cause downhole string failure or even well field accidents.Therefore,considering the flow channel features in the tubing string of sine buckling and helical buckling,based on the theory of the natural gas flowing dynamics,the CFD model and sand erosion model were established for a high pressure and high production gas well in Kela 2 gas field.Numerical simulation was conducted on the flow performance of natural gas in sine and helical buckled tubing string,and the erosion velocity and shear stress of sand flowing in the tubing was studied.The force and erosion law of natural gas to buckled tubing were obtained.It provided a reference for real-time prediction of erosion damage in high pressure and high production gas wells,and a theoretical basis for the proposal of erosion damage prevention measures.

A comb-like acrylamide copolymer (HCJ-1) was synthesized by using aqueous free radical polymerization of acrylamide (AM) as main monomer and ether carboxylate as functional monomer. The copolymers were characterized with FT-IR and SEM. The SEM results show that the molecular structure of copolymer is extended in salt water. It is proved that the copolymer shows good salt resistance.The solution properties of HCJ-1 were studied and compared with those of partially hydrolyzed polyacrylamide (HPAM). The experimental results show that the obtained HCJ-1, compared with HPAM, exhibits a dramatic enhancement in the salt-resistant properties. The apparent viscosity retention rate of 1.5 g L HCJ-1 aqueous solution and salt solution after 180 days at 60 °C are 70.6% and 64.5%, respectively, exhibiting good thermal stability. In addition, HCJ-1 solution also displays the excellent shearing resistance. In a word, the experimental results show the HCJ-1 is a promising profiling agent for high salinity reservoir.

The drilling problems,such as the loss,blowout,borehole collapse and sticking are normal with the perpetual exploration and development of Nanpu oilfield in over-balance drilling. It not only makes drilling cost and period increase,but also damages the reservoir. With the formation condition of Well 128 Dong3 in Nanpu oilfield,it evaluates and optimizes aerated under-balance drilling is the best under-balance drilling program for the well.