应用地化录井技术判别低电阻率油层

鄂尔多斯盆地三叠系延长组储集层为低渗透、特低渗透储集层.该盆地姬塬地区长2段、长4 5段地层由于受储集岩中黏土矿物赋存状态、层间水、束缚水含量和地层水矿化度等因素的影响,局部形成低电阻率油层,给常规录井、测井带来一定的困难.储集岩热解技术作为成熟的地化录井技术,在储集层含油性判别方面具有明显的优势,热解烃总量主要反映储集岩油气充注程度,是有效的储集岩含油性判别指标.应用地化录井技术,通过对实际资料进行分析,认为研究区长2段、长4 5段油层段储集岩热解烃总量大于10.0 mg/g,油水同层段储集岩热解烃总量为5.0～10.0 mg/g,含油水层段储集岩热解烃总量为2.5～5.0 mg/g,水层段储集岩热解烃总量小于2.5 mg/g.分析结果表明,应用该指标对低电阻率油藏的判别效果相对明显.

Applying geochemical logging technique to judge low resistivity pay zone

The reservoirs of Erdos Basin Mesozoic Triassic Yanchang Team are low permeable and very low permeable reservoirs. The Chang 2 member and Chang 4+5 members formations in Jiyuan area, due to the effect of clay mineral existing status in reservoirs, interlayer water, irreducible water content, formation water mineralization degree on them, the low resistivity pay zones were formed in some areas, thus bringing a certain difficulties to conventional mud logging and wireline logging. As a mature geochemical logging technique of reservoir-rock pyrolysis, it has obvious superiorities in reservoir oil-bearing discrimination. Total pyrolysis hydrocarbon content mainly reflects reservoir hydrocarbon injection degree, which is a valid index for reservoir oil-bearing discrimination. Applying geochemical technique and making analysis of the real data, the authors thought the sum of reservoir rock pyrolysis hydrocarbon for Chang 2 and Chang 4+5 members is more than 10.0 mg/g, the sum for reservoir rock pyrolysis hydrocarbon of oil-water layers is 5.0 to 10.0 mg/g, the sum for reservoir rock pyrolysis hydrocarbon of oil-bearing water layers is 2.5 to 5.0 mg/g and the sum for reservoir rock pyrolysis hydrocarbon of water layers is 2.5 mg/g. The results indicated that the effect of applying these indexes to discriminate low resistivity pay zones is relatively obvious.