Preferential petroleum migration pathways in eastern Pearl River Mouth basin, offshore South China Sea

Abstract

Secondary petroleum migration in the eastern Pearl River Mouth basin was modeled us-ing the three-dimensional PATHWAYSTM model, which assumes that the positions of petroleum migration pathways are controlled by the morphology of the sealing surfaces. The modeling results have accurately predicted the petroleum occurrences. Most commercial petroleum accumulations are along the predicted preferential petroleum migration pathways (PPMP), and most large fields (petroleum reserves greater than 1×10 8 t) have more than one preferential petroleum migration pathways to convey petroleum to the traps. The lateral migration distance for oil in the LH11-1 field, the largest oilfield so far discovered in the Pearl River Mouth basin, was more than 80 km. The case study suggests that in lacustrine fault basins, petroleum can migrate over a long distance to form large oilfields without driving force from groundwater flow. The focusing of petroleum originating from a large area of the generative kitchens into restricted channels seems to be essential not only for long-range petroleum migration in hydrostatic conditions, but also for the formation of large oil or gas fields. The strong porosity and permeability heterogeneities of the carrier beds and the relatively high prediction accuracy by a model that does not take into consideration of the effect of heterogeneity suggest that the positions of petroleum migration pathways in heterogeneous carrier beds with relatively large dipping angles are determined primarily by the morphology of the sealing surfaces at regional scales.KEY WORDS: preferential petroleum migration pathway, modeling, lacustrine fault basin, Pearl River Mouth basin.

Preferential petroleum migration pathways and prediction of petroleum occurrence in sedimentary basins: A review

“…Yu et al (2009) used a parameter called migration predictive index (MPI) to assess the accuracy of the model prediction, and defined MPI as MPI = [prediction of discoveries (%) + prediction of dry holes (%)]/2. In the Eastern PRM Basin, the modeling results give an MPI 1 (prediction of discoveries) of 97% (37 drilled structural traps), and an MPI 2 (prediction of dry holes) of 78.8% (18 drilled structural traps), with an overall MPI of 87.9% (Yu et al, 2009). …”

“…In recent years, several investigators have studied petroleum migration pathways and the distribution of oil and gas at a depression or sub-basin scale (e.g., Hindle, 1997;Bekele et al, 2002;Terken and Frewin, 2000;Terken et al, 2001;Luo et al, 2007;Hao et al, 2007;2009c;Yu et al, 2009). These case studies provide evidence concerning the major controls of the petroleum migration pathways on a large scale.…”

“…Garven (1989) believed that groundwater flow was a key to the formation of the giant oil sands deposits of the Western Canada Sedimentary Basin, and Bekele et al (2002) stated that oil could not have experienced long-range migration to form the distant oil fi elds in the Viking Formation in the Alberta Basin. In the Eastern PRM Basin, oil originating from the southern limit of the generative kitchen must have migrated more than 80 km to fi ll the LH11-1 fi eld (Yu et al, 2009, Fig. 2(a)), and oil originating from the kitchen center must have migrated a much longer distance.…”

“…The filling of the LH11-1 field (oil reserve of about 2.4×10 8 ton) and the predicted migration pathways suggest that petroleum could migrate over a long distance in hydrostatic conditions (without hydrodynamics) to form a large oilfi eld. It is noticeable that in the Eastern PRM Basin, oil originating from a large portion of the generative kitchen focuses through "small streams" into discrete "mainstreams" or preferential petroleum migration pathways (PPMP), and these discrete "petroleum mainstreams" merge further to form "channels" to convey oil into the LH11-1 structure (Yu et al, 2009, Fig. 2(a)).…”

Complex petroleum migration and accumulation in central region of southern Junggar basin, Northwest China

“…This article represents an attempt to understand this complexity. Thus, the results have regional implications, and can additionally provide a reference for studies in other areas with similar complex tectonic settings (cf., Yu et al, 2009;Zou et al, 2008;Cao et al, 2006).…”