Comprehensive Evaluation Of Donghe Sandstone Reservoir In32Area Of HDD Oil Field

The study of Donghe sandstone had acquired great success and breakthrough since1989in HDD oil field.With the continuous development of HDD oil field, it added lots of drilling wells and obtained a mount of core data, testing data, logging data and so on. it is necessary to understand the characteristics of DongHe sandstone in-depth, evaluate the Donghe sandstone reservoir on the basis of the fine geologic description, then reach the purposes of guiding the adjustment of development program, this paper divided the small layer, studied the sedimentary, interpreted the reservoir parameters, identified the fluid, researched on the reservoir characteristics and finally evaluated the reservoir types under the guide of theory and methods of high-resolution sequence stratigraphy, sedimentology, logging geology, reservoir description on the bases of geological characteristic, core data, logging data, seismic data and test data.Using the principles of high resolution sequence stratigraphy, and combined with the predecessor’sequence study on Donghe sandstones, it identified two sequences (sequences Ⅰ and sequences Ⅱ) and ten small layer on the Donghe sandstone reservoir in32Area of HDD oil field. The sea levels is rising, the coastline is prograding to the land and the sand body is gradually overlapping to the coastline when the sequences I deposit. The sea levels is dropping and the sand body is gradually progradaing to the coastline when the sequences Ⅱ deposit.After the division to the small layer on the each single well,we established the fine stratigraphic framework of Donghe sandstone reservoir, in order to study the plane distribution characteristics of every small layer.Through studying the sign of sedimentary facies,of the color, rock ore composition, grain size characteristics, sedimentary structure and so on,combined with log facies research, we can think that the sedimentary facies is no barrier wave accused of sandy transgresive deposits in the Donghe sandstone reservoir.We divided the ransgresive deposits into coastal dunes, the hubin, foreshore and near the shore four Subfacies. Based on this we divided the sedimentary subfacies of47wells in the area, under the control of the small layer contrast,we study the sedimentary subfacies" plane distribution characteristics of every small layer. It is based on the core scale logging,after the study of core scale logging, core homing, standardization and normalization of logging, it is need to establish neural network interpretation model for porosity and permeability,the results show that have achieved high accuracy explaintion.Using properties and logging data, taking different method to establish the identifying standards for fluid, it is identified the fluid types in the study area and established the elevation of oil-gas contact in each well point. The research results shows that there is a uniform oil-water contact whose elevation is-4160m of Donghe sandston in32area of HDD oil field.In the study of core property characteristics in the donghe sandstone reservoir, combined with the former’s reservoir parameters explanation, under the control of the small layer contrast,we can study the plane distribution characteristics of porosity and permeability.According to the lithology and property characteristics of donghe sandstone,the interlayer of it in study area will be put into three categories:interlayer of calcareous sandstone, interlayer of laminated shaly sand calcium and interlayer of laminated shaly sand. From summing up the well logging response’s characteristics of three categories interlayer, and establishing the well logging criterion of identification, and taking identification to the interlayer in single well, in order to study the plane distribution characteristics of every interlayer.Synthesized the study in front, using the multifactor comprehensive evaluation method to classify the reservoir.according to the geological characteristics and the explanation results of the area, we select the sand body thickness, porosity, permeability, pore characteristic and interlayer thickness as the evaluation parameters,these evaluation parameters can reflect reservoir quality characteristics, and then calculated the evaluation scores of evaluation parameters,simultaneously according to the relative importance of the parameters we can assign different weight coefficient to them, finally calculated the comprehensive evaluation score of each unit. According to the different scores we can divide the Donghe sandstone reservoir into three categories.After the reservoir comprehensive evaluation of each well, in order to study the plane distribution characteristics of each layer’s reservoir category.Through the study we can conclude that the most favorable small layer is the sixth small layers and the most favorable block is Strip area which formed by H41Wells,H42Wells and H21well.