Biomarker parameters of transgressive member have specific characteristics:Pr/Ph less than 1,higher abundance of steranes,abundance of C 27 are similar to C 29 stertane,tricyclic terpane with feature of C 21 C 24 and isotopic composition of n alkanes enriched 12 C.
Such biomarker parameters as OEP,CPI,22S/(22S +22R)of C32 hopane,20S/(20S+20R) and ββ/ (αα+ββ) of C29 sterane indicate that the source rocks of upper Es4 and mid-lower Es3 were basically mature and benefit to oil-gas generation.
On the basis of variations in molecular biomarker parameters that reflect the type of source organic matter and the facies conditions of its accumulation and early diagenesis, the oils are classified with three groups.
We have investigated the distributions of alkylcarbazoles in a series of crude oils with different biodegradation extents, in combination with biomarker parameters, stable carbon isotopic ratios and viscosities.
In highly mineralized samples, hydrogen donation for thermochemical sulfate reduction (TSR) occurred in alkylated phenanthrenes and naphthalenes, leading to the decrease of 12 biomarker parameters during the Kupferschiefer mineralization.
This demonstrates the necessity of determining several biomarker parameters simultaneously as one single biomarker may fail to respond to potentially harmful compounds.
Individual unique biomarker parameters only become valuable and meaningful when they are used together and agree with other biomarker parameters.
Assuming that the cross section of entry is circular, and rock pressure in an undisturbed condition is σ_y~(∞)=Y=γh, σ_x~(∞)=X=λγh, τ_xy~(∞)=0.The author has investigated the elasto-plastic stress field around such entry and found that the elasto-plastic boundary is no more circular, but having a different form the equation of which may generally be: b=b_0+λ_2b_1(??)λ_2--small parameter.