Reservoir Evaluation Of Huangliu Formation In Dongfang Area, Yinggehai Basin

Yinggehai Basin, located at the west of the Hainan island, is shaped like a north-westward fusoid with an acreage of12.7×104km2. It is known as a Cenozoic basin. It is developed on the passive continental margin with fast subsiding tertiary, where abnormal high temperatures and high pressures (HTHP) have been encountered and mud diapirs are well developed. Problems emerges as the process of the exploration, one is the multi-provenance and complex sedimentary systems, another is the diapirs is controlled by high temperatures and high pressures. The normal method to evaluate reservoir is no longer applicable for here concerning about the controlling factors.This paper summarizes the geological background of the region, the evolution characteristics of the distribution in the shallow sedimentary facies (Littoral, Neritic and Bathyal). the paper starting with the evolution character of temperature and pressure in Dongfang area, combining the reservoir temperature and pressure sensibility test in the laboratory, analyses the geologic process affecting the reservoir. Then classify the reservoir by the physical property, the sedimentary facies as well as the variation law of permeability on the condition of tempreture-changing.First of all, the petrological characteristics,diagenesis, pore structure and reservoir properties of the shallow reservoir rocks in Yinggehai Basin is studied on the basis of having observed the core observation and experimental analysis. The conclusion is that the best reservoir is in the Dongfang13block, the Dongfang1block and the Dongfang29block take the second place.Secondly, the controlling factors of reservoir properties is studied. The reservoir properties in Yinggehai basin has the three control factors:sedimentary facies, diagenesis and overpressurization. the favorable sedimentary facies to affect the physical properties is found; the affects of compaction, cementation and dissolution on reservoir properties is compared; the influence of the overpressurization on the diagenesis is studied.Thirdly, data from the HDHP sensitivity test and the the permeability test on the condition of tempreture-changing was classified and to summarize variation law of the permeability with temperature.That the small difference between the core porosity and permeability and the well logging porosity and permeability, so well logging porosity and permeability can be used as valid data to evaluate the reservoir; determine the porosity and permeability of the lower limit in this studied area.At last, the distribution and evaluation the of reservoir is worked on the basis of sedimentary microfacies. In the study of All aspects of influencing factors in reservoir properties, reference to the geological background and sedimentary facies, pore types, physical properties conditions, classification and evaluation of the middle-shallow reservoir in The Yinggehai Basin.