莺歌海盆地东方区高温高压带黄流组储层特征及高孔低渗成因

摘要

莺歌海盆地中央底辟区中深层高温高压带获得了重大油气突破，为传统油气勘探开辟了新领域。在对东方区高温、高压带黄流组储层岩性、成岩作用、物性和微观孔喉结构等储层特征研究的基础上，划分了黄流组储层的类型，并明确了黄流组储层高孔、低渗的成因。研究表明，中央底辟带东方区黄流组储层岩性主要为粉砂岩，压实和胶结等成岩作用较弱；储层物性以中孔、中－低渗为主，储层物性差异较大；储层孔喉分布具有较强的非均质性，不同物性储层的孔隙半径差异不大，但平均喉道半径差异较大；根据泥质含量、渗透率、平均喉道半径和排替压力，将黄流组储层划分为中孔－中渗微含泥细喉储层、低渗含泥细喉Ⅰ类储层、低渗含泥细喉Ⅱ类储层及低孔－特低渗泥质微细喉储层；高温、高压带储层的形成与超压和高温热流体活动关系密切，但渗透率主要受沉积作用的控制，岩性细、泥质含量高是低渗储层形成的主要原因。%The significant oil and gas exploration breakthrough made in the middle-to-deep-layers in HTHP( high tempe-rature and high pressure ) central diapir zone in DF area of Yinggehai Basin poses a big challenge to traditional oil and gas exploration theories.Lithology,diagenesis,physical properties and microscopic pore throats analyses were carried out on the reservoirs in the Huangliu Formation of the area to classify the types of the reservoirs and understand the genesis of high porosity and low permeability formation .The results indicate that the reservoirs are mainly siltstone experienced weak compaction and cementation .The physical properties of the reservoirs are dominated by medium porosity and medium-to-low permeability with great variance .Pore throat size distribution of the reservoirs is highly heterogeneous:reservoirs of different physical properties have similar pore size but greatly different average pore throat sizes .According to shale con-tent ,permeability ,average throat size and displacement pressure ,the reservoirs can be categorized into four types:slightly shaly reservoirs with medium porosity ,medium permeability and small throat size;type Ⅰand type Ⅱmoderately shaly reservoirs with low permeability and small throat size;shaly reservoirs with low porosity and extra-low permeability and fine-to-small throat .Evident shows that the formation of the reservoirs was closely linked to overpressure and active high -tempe-rature thermal fluid flow .However ,the permeability of the reservoirs was mainly controlled by sedimentation .Fine grain size and high content of mud are considered to be the main reasons for the formation of the low permeability reservoirs .