Experimental and Statistical Study on Wellbore Scaling Mechanisms and Characteristics for Huanjiang Oilfield.

Wellbore scaling is a complex and one of the common problems encountered during the depletion of an oilfield. Many studies have been conducted on general scale mechanisms, scale predictions, and removal measurements. However, the detailed study of the scaling characteristics and mechanisms in Huanjiang oilfield is limited. The objective of this work is to investigate the scaling mechanisms and characteristics to provide guidance for scale inhibitor selection, synthesis, and testing in the Huanjiang oilfield. Ion chromatography (IC) was used to test the composition of 100 water samples, and energy dispersive spectroscopy (EDS), scanning electron microscope (SEM), and X-ray diffraction (XRD) were utilized to analyze the composition of 120 wellbore scale samples that were collected from the Huanjiang oilfield. The results show that the water types of formation and groundwater are CaCl₂ and Na₂SO₄, respectively. The oil wells produced from Chang 4 + 5 , Chang 6, and Chang 8 reservoir layers in the development of Yanchang group are mainly calcium-based scale (CaCO₃ and CaSO₄), supplemented by wax deposition scale, corrosion scale, and NaCl and KCl crystal scale. In contrast, the oil wells in Yan'an group (Yan 6, Yan 7, Yan 8, Yan 9, and Yan 10 reservoir layers) are mainly wax deposition scale and corrosion scale. [ABSTRACT FROM AUTHOR]