热采过程中硫化氢成因机制

Hydrogen sulfide formation mechanism in the process of thermal recovery

为了防范稠油油藏注蒸汽开采过程中井口产出硫化氢所造成的安全隐患,增强热采油井安全生产水平,亟需对稠油热采过程中硫化氢的来源及成因机制开展相关实验研究。对辽河小洼油田洼38区块的岩心、原油和产出水3种不同物质开展了含硫量测定、硫同位素分析和H2S生成热模拟实验。实验研究结果表明:稠油热采中生成的硫化氢主要来源于岩心和稠油;在硫同位素分馏过程中,形成硫化物(H2S)的δ34S反映了硫酸盐热化学还原过程中硫在较高温度下的分馏特征;硫化氢的生成机理主要为高温高压酸性环境下稠油水热裂解和硫酸盐热化学还原之间的交互作用。

In order to prevent potential safety hazard which is caused by hydrogen sulfide（H2S） produced from wellhead during steam injection in heavy oil reservoir,and increasing safe production level of oil well,it is necessary to carry out experimental research on the source and formation mechanism of H2S during thermal recovery of heavy oil.This study conducted sulfur measurement,isotope analysis,and thermal simulation experiment of H2S generation using core,crude oil,and output water samples from the Wa-38 block in Xiaowa oilfield,a heavy oil block in Liaohe oilfield,Panjin,China.During thermal recovery of heavy oil,H2S is mainly derived from core and heavy oil.In the sulfur isotope fractionation process,the δ^34S value of sulfide product （H2S） reflects the fractional characteristics of sulfur at high temperature during thermal chemical reduction of sulfate.Regarding the formation mechanism,H2 S is mainly formed by interaction between aquathermolysis of heavy oil and thermal chemical reduction of sulfate under high-temperature,high-pressure and acidic conditions.