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.