陆相断块油藏正构烷烃分布模式及其意义

DISTRIBUTION PATTERNS OF NORMAL ALKANE AND THEIR SIGNIFICANCE IN CONTINENTAL FAULT-BLOCK OILFIELD

国内外研究合采井单层原油产量的专家大多使用饱和烃气相色谱法 ,而且认为油藏内部正构烷烃组成及分布基本相似 ,难以应用 ,而异构烷烃应用效果较好。胜利油区临南油田成藏时间短、油源单一 ,其异构烷烃极为相似 ,而中、高碳数正构烷烃分布模式具有较为明显的区别 ,可以用来有效地建立单层标准谱图和进行合采井单层原油贡献计算。中、高碳数正构烷烃分布模式区别明显的原因主要是陆相砂体变化大 ,不同的矿物成份对同一原油具有不同的吸附能力 ,其间可能的化学作用也不相同 ,在高碳数范围正构烷烃图谱表现得尤为突出。断块油藏内部正构烷烃分布模式变化显著的特征 ,使成分高度均一的油藏合采井计算单层贡献成为可能。

Gas chromatograph of saturated hydrocarbon is generally used in the study of single pay contribution in commingled producing wells both at home and aborad,because it is believed that the composition and distribution of normal alkane in the oil reservoirs are basically similar,and are very difficult to be used to solve the above problem; while the application of isoalkane,proves to be very effective.Through the research work made in Linan area, Shengli oilfield,it is found that the isoalkanes are very similar, since the reservoiring time is not long and the oil source is unitary, but the normal alkanes with moderate to high carbon numbers have apparent differences and can be used in establishing single pay's standard pattern of gas chromatogram,and in calculating the single pay's oil contribution in commingled producing well. There are several reasons that cause the different patterns of normal alkanes with moderate to high carbon numbers, for example, the large changes of continental sandstones and their different mineral compositions would have different absorbability and possible chemical reactions between oil and mineral. This phenomenon has important application value in calculation of oil contribution of single sandstone layer in commingled producing well in non-marine fault-block oilfield.