华池油田华152区低渗透砂岩储层敏感性及其形成机理

SENSITIVITY CHARACTER AND ITS MECHANISM ANALYSIS OF LOW-PERMEABILITY SAND BODIES IN H152 BLOCK OF HUACHI OILFIELD

华池油田华152区长3油层组储层为曲流河三角洲粉-细粒长石砂岩、岩屑长石砂岩，矿物成分成熟度低，结构成熟度中等，填隙物含量较高，孔隙结构以中孔细喉型为主，物性较差，属低渗透储层。主要成岩矿物（伊利石、绿泥石、伊／蒙混层、高岭石、方解石、白云石等）使储层对外来流体有不同程度的敏感性反应。“五敏”实验结果表明，储层速敏和碱敏均为弱-中等偏弱，部分伊/蒙混层、绿泥石、碳酸盐矿物含量高的样品表现出强水敏、强酸敏、强盐敏的特征；油田水结垢实验表明，注入水与地层水、储层岩石不配伍产生盐垢CaCO3，CaSO4，实验为开采过程中回注地层水和注气开采等工艺提供油层保护的理论依据。

Chang-3 reservoir sandstones of H152 block in Huaehi oilfield belong to meandering river delta sediment. They mainly consist of silt-fine grained arkoses and lithic arkoses with low compositional maturity, medium structural maturity, and high content of clay minerals. Medium sized pore and fine throat indicate the characteristics of low-permeability. Main types of diagenetic minerals include illite, chlorite, mixed illite/semectite, kaolinite, calcite and dolomite and so on. Experiments show that they have a variety of sensitivities to external fluid and iniected water incompatible with the formation water. These sand bodies are of weak water sensitivity,weak-medium rate sensitivity, generally no acidic sensitivity, weak-medium alkaline sensitivity, and weak salt sensitivity. Calcium carbonate and calcium sulfate may be resulted from the reaction between incompatible injected water and the formation water. This paper has also discussed the reservoir protection during the development, such as inject formation water and gas.