Simulation of crude oil cracking and gas generation with semi-open condition, Baiyun Sag, Pearl River Mouth Basin

Abstract

In order to study the mechanism and product compositions of oil cracking, crude oil samples from the Zhuhai Formation of the Baiyun Sag of Pearl River Mouth Basin were carried out for the high-temperature, high-pressure pyrolysis with different heating rates with the pressure close to the conditions of underground. The underground fluid was also considered to be included with a semi-open condition for the pyrolysis, the gas yields and gas composition characteristics were then analyzed. Results showed that crude oils start to crack at 365 ℃, and the cracking yield increases with the increase of temperature. At a heating rate of 20 ℃/h, the final yields (at 550 ℃) of pyrolysis gas, hydrocarbon gas and non-hydrocarbon gas were 580.13, 394.25, and 185.88 mg/g, while at a heating rate of 60 ℃/h, these values increased to 707.68, 485.77, 221.91 mg/g, respectively. The composition of hydrocarbon gases at different heating rates also varied, and these variations were assumed to be related to the difference of cracking mechanisms of crude oils at different temperatures of pyrolysis. According to the composition characteristics of pyrolytic gas products, most of the gases from crude oil cracking has a relative higher content of high molecular weight hydrocarbon gas, thus these compounds can be used as an auxiliary index to distinguish crude oil cracked gas from kerogen cracked gas.

Keywords

• crude oil pyrolysis
• pyrolysis simulation experiment
• semi-open system
• pyrolysis gas yield
• natural gas
• zhuhai formation
• baiyun sag
• pearl river mouth basin