东营凹陷地层水化学特征与油气聚集关系

对东营凹陷沙河街组地层水化学场的研究发现,地层水的总矿化度具有明显的垂向分带性。沙四段矿化度最高,向上逐渐降低。根据地层水中Ca2+和K++Na+含量随Cl-浓度增大而升高的特征,提出该区地层水化学成分来自于地下岩盐的溶解。水型有CaCl₂型、NaHCO₃型、MgCl₂型和Na₂SO₄型4种,其中,NaHCO₃型水的比重大小与地层水矿化度呈反相关关系。垂向与侧向矿化度分布特征表明,东营凹陷内地层水的流动受断裂与沉积砂体的控制。地层水作为盆地流体的一个重要组成部分,其演化反映了盆地内油气运移、聚集的规律。地层水流动样式为盆地内自生自储式和下生上储式油气藏的形成提供了一个有力的证据。 

RELATIONSHIP BETWEEN THE CHEMICAL CHARACTERISTICS OF FORMATION WATER AND HYDROCARBON ACCUMULATION IN THE DONGYING SAG

It was discovered by study on the chemical field of the Shahejie formation water in the Dongying Sag that the total dissolved solid ( TDS ) of formation water has explicit vertical zonality.The value of TDS is the highest in the Sha 4 Member,and reduces gradually upward. According to the feature that the Ca 2 and K Na contents in formation water get higher with the increasing of Cl - concentration,it is suggested that the chemical components of formation water in this area come from the dissolution of subsoil rock salt.Among CaCl 2 , NaHCO 3, MgCl 2 and Na 2SO 4 four water types,the specific gravity of NaHCO 3 typed water has inverse correlation relationship with the TDS of formation water.The characteristics of vertical and lateral TDS distribution show that the flow of formation water within the Dongying Sag is controlled by faults and sedimentary sand bodies.Formation water is a major component of basin fluid,and its revolution reflects the rules of hydrocarbon migration and accumulation in the basin.The flow styles of formation water provide a powerful evidence for the formation of "self generation,self accumulation" and "lower generation,upper accumulation" two patterns of hydrocarbon pools in the basin.