Papers by Author: Cheng Qiang Ren

Abstract: The deposition of BaSO₄ scale is always found in the oilfield. It is difficult to be removed. Therefore, it plays a negative role to the production. The effects of temperature and water chemistry on BaSO₄ scale have been investigated by using the conductivity method in this work. An environment-friendly copolymer was prepared to control the scaling of BaSO₄. The copolymer was proved by static scale inhibition method, and weight-loss test that it has excellent scale inhibition performance and corrosion inhibition efficiency. Furthermore, FTIR spectra was used to prove that the scale inhibitor was polyepoxysuccinic acid (PESA).

Abstract: The stability of interface between bond cement and tubular steel is very important to the integrality of oil and gas wells. However, research on the degradation of the interface in aggressive solution is absent to date. This work devotes to discover the relationship of electrochemical parameters and interfacial development during early stage of corrosion by analyzing the electrochemical results. Dielectric spectroscopy obviously describes the stability change of passive film of steel, and Bode plot supports the structure change of cement. The early stage of immersion in aggressive solution is dominated by competition of hydratation and corrosion.

Abstract: Carbon dioxide corrosion is a very complex electrochemical process. Compositions of formation water in different gas and oil wells are various, which effects on the carbon dioxide corrosion of tubular steel. HCO₃^- and SO₄^2- were studied in order to further understand their role on the corrosion process. The results show marked difference when they are the main composition while others conditions is the same. HCO₃^- mitigates the corrosion, because its participation in cathodic and anodic reactions accelerates passivation. However, corrosion in formation water mainly containing Na₂SO₄ is severe, which presents higher general corrosion rate and more dangerous localized corrosion.

Abstract: Scale deposition, including organic and inorganic substances, is always found in oil and gas field due to the changes of environmental factors in production. As a result, it is puzzled by the formation damage and wellbore plug. In fact, many wells face to complex scale, and even it is difficult to identify the type. In order to simplify treatment and promote efficiency, it is necessary to develop combining scale remover. A compound chemical scale remover is designed to relieve the complex scale comprised of calcium carbonate, guar gum and paraffin. Inorganic scale removing efficiency, paraffin removing rate and viscosity reduction ratio are used to determine the main agents respectively. Surfactants and lacquer solvent are added to develop an emulsion solution due to the incompatibility of water solution and organic solvent. This formula can dissolve 72.58% weight of calcium carbonate, reduce the viscosity of guar gum to 2.736mPa×s and remove the paraffin with a rate of 0.018 g/min.