| Author's Name: ZHANG Qiang, FAN Guozhang, WANG Hongping, WANG Xuefeng,
YANG Zhili, ZHANG Yuanze, TIAN Hongxun, Li Li |
| There are relatively few summaries and comparative studies on the formation conditions, hydrocarbon
accumulation models, and main controlling factors of carbonate oil and gas fields in the South China Sea (SCS), making it
difficult to guide oil and gas exploration in similar areas of the SCS. Based on the tectonic background and basement
control factors, the carbonate platforms in the SCS are classified into three types: stable, fault-block and inverted. Typical
oil and gas fields in each type of platform are selected for dissection to analyze the characteristics of hydrocarbon sourcereservoir-cap conditions, hydrocarbon accumulation patterns and main controlling factors. The research suggests that: (1)
The source rocks of carbonate reservoirs in the SCS are mostly Oligocene-Miocene coal rocks and coal bearing mudstones
form. The reservoirs are mostly composed of Middle-Upper Miocene biogenic reef limestone and calcarenites, with
porosity mainly ranging from 20% to 25%, and permeability mainly atthe range of(100-200) × 10-3μm2. The cap rock is Upper
Miocene marine mudstone. (2)The three types of platforms exhibit distinct hydrocarbon accumulation models: stable
platforms follow a "lower generation, lateral reservoir" model with long-distance migration; fault-block platforms adhere
to a "lower generation, lateral reservoir" model with short-distance migration; inverted platforms exhibit a "lower
generation, upper reservoir" model with short-distance migration. (3)The three types of carbonate platforms have different
potential exploration areas: stable platforms focus on carbonate buildups developed above unconformities or sandstone
bodies; fault-block platforms focus on the carbonate buildups on the horst adjacent to the fault depression. For reversed
platforms, priority should be given to the carbonate buildups directly developed on the depression, which is also the most
important exploration area for carbonate reservoirs in the SCS at present |
