Abstract:

Abstract: This paper discusses hydrocarbon accumulation patterns of Moxizhuang oilfield of the Junggar Basin based on a comprehensive analysis of oilwater relationship,fault occurrence and hydrocarbon accumulation background.The reservoir of J₁s²⁽²⁾(the lower second member of the Jurassic Sangonghe Formation) in Moxizhuang oilfield has a uniform oilwater system with a normal instead of inverted oilwater relationship.Seismic attributes of intervals with welldeveloped coal beds reveals that the previously interpreted major faults are artifacts resulted from seismic reflection of the coal seams,and no large faults are developed in the Sangonghe Formation,no faultsealing trap conditions exist.Hydrocarbon accumulation conditions and distribution characteristics are different inJ₁s²⁽¹⁾ (the upper second member of the Jurassic Sangonghe Formation) and J₁s²⁽²⁾ reservoirs.The J₁s²⁽¹⁾ reservoirs are developed in underwater distributary channel sandbodies of meandering river deltaic front facies,with the favorable reservoirs laterally being in strip distribution.In contrast,the J₁s²⁽²⁾ reservoirs are developed in distributary channel sandbodies of braided river delta facies,with the favorable reservoirs laterally in continuous distribution.The Moxizhuang oilfield is a structurallithologic reservoir that is controlled by both structure and sedimentary microfacies and is still in the posttilting dynamic adjusting process.There exists a uniform oilwater contact in J₁s²⁽²⁾ with occurrence the same as that of the updipping sandbody.

Key words:  , Key words： oilwater distribution,hydrocarbon accumulation pattern,sedimentary microfacies,structurallithologic reservoir,Moxizhuang oilfield,Junggar Basin