热化学硫酸盐还原反应对原油C_7轻烃参数的影响

Effects of thermochemical sulfate reduction on C_7 light hydrocarbon parameters

热化学硫酸盐还原反应直接影响C_7轻烃参数的有效性及使用范围。在360℃,持续时间分别为12、48、312h条件下,进行了室内不同储层矿物介质作用下TSR模拟实验,研究了Schaefer、Thompson、Halpern和Mango等C_7轻烃参数在TSR作用过程中的演变特征及影响因素。实验结果显示:随实验时间持续或TSR作用程度增加,Schaefer参数逐渐减小,它将因此低估原油成熟度;Thompson参数庚烷值、石蜡度和芳香度呈上升趋势,异庚烷值在含黏土矿物系统内显著降低,在含碳酸盐岩系统内先升高后降低,这将使得相关图版的解释复杂化;Halpern参数中轻质芳烃与环烷烃比值显著增加,正构烷烃(异构烷烃)与环烷烃比值有不同程度减小;Mango参数K1呈增大趋势,N2、P2和P3等不再适用于划分原油类型。在实验持续时间相同的条件下,Schaefer参数、庚烷值、石蜡度和芳香度在含黏土矿物系统内通常要比含碳酸盐系统内高;与无矿物系统相比,K1在含储层矿物,尤其蒙脱石系统内较高。这表明TSR作用过程中储层矿物对C_7轻烃参数仍有较为显著的影响,使用时需要慎重。

Thermochemical sulfate reduction （TSR） has a significant impact on the effectiveness and application of Ca light hydro- carbon parameters in erude oils. A series of experiments simulating TSR process were conducted with the presence of reservoir minerals in the laboratory at 360℃ for 12, 48 and 312 h to investigate the evolution tendencies of Schaefer, Thompson, Halpern and Mango parameters and controlling factors during TSR. The experimental results show that with the duration time increasing or TSR advancing, Schaefer parameters decrease gradually, resulting in underestimating the thermal maturity of crude oils; Hep- tane value, n-Ca/methylcyclohexane and toluene/n Ca increase subsequently and are usually greater in experiments with silicates present, isoheptane values in experiments with containing clays decrease continuously and increase firstly and then decrease in ex- periments with carbonates present. This makes it to be more complex when explaining relevant plots; For Halpern parameters, the ratios of light aromatics to cycloalkanes increases and the ratios of normal alkanes and isoalkanes to eyeloalkanes decrease with the extent of TSR increasing to varying degree; The values of K1 increase with TSR ongoing, N2, P2 and P3 cannot be used to clarify the groups of TSR-altered oils. With the equivalent heating time, Schaefer parameters, heptane value, paraffinicity （n-C7/ methyleyelohexane） and aromaticity （toluene/n-Ca） are usually higher in experiments containing silicates relative to that in exper- iments containing carbonates; gl values are comparatively greater in experiments with mineral additives, in particular montmoril- lonite present relative to those in experiments with mineral additives absent. This indicates that reservoir minerals still have an important impact on C7 light hydrocarbon during TSR, great caution is therefore required during the process of application.