江汉盆地潜江凹陷潜江组非砂岩储层改造实验

组成江汉盆地潜江凹陷潜江组盐间段非砂岩储层的岩石主要为泥晶白云岩、钙芒硝岩、泥岩及其混积岩,孔渗性普遍较差。实验选用饱和盐水、饱和盐水+醋酸及饱和盐水+醋酸+盐酸等3种不同溶液,对王云10—6井潜二段的4号样(含钙芒硝泥晶白云岩)和王平1井潜三段的8号样(含云细—中晶钙芒硝岩)进行处理。由毛管压力曲线分析可知,处理后的岩样排驱压力明显减小,4号岩样降幅达62%,8号岩样达88%;最大孔喉半径显著增加,4号和8号岩样的增幅分别为187%和743%,孔喉分选系数得到明显提高;2个岩样的孔隙度分别增加了1倍多。实验结果表明,处理后的岩样骨架保持完好,孔渗性得到了有效改善。     

DEPOSITIONAL ENVIRONMENTS AND SEQUENCE STRATIGRAPHY OF THE EARLY TRIASSIC KANGAN FORMATION IN THE NORTHERN PART OF THE PERSIAN GULF: IMPLICATIONS FOR RESERVOIR CHARACTERISTICS

The Early Triassic Kangan Formation is the main reservoir for natural gas in SW Iran and the northern Persian Gulf and is equivalent to the Upper Khuff Formation. Analyses of the formation at the offshore Salman and Minab oilfields indicate that it is composed of 14 facies deposited in tidal flat, lagoon and oolitic barrier settings in the inner part of a carbonate ramp or platform. Vertical variations of microfacies and gamma-ray log profiles show that the formation consists of three depositional sequences (KG1–3), each consisting of transgressive and highstand systems tracts and each bounded above by a type 2 unconformity. Porosity in the Kangan Formation is dominated by fracture and intercrystalline pore types in highstand systems tract deposits. From a study of core plug porosity and permeability, ten flow units were recognized. Flow units GF1, GF5 and GF8 represent zones with similar flow and storage capacities. Flow units GF3, GF7 and GF9 were attributed to zones of higher flow capacity, and units GF2, GF4, GF6 and GF10 were interpreted as zones with higher storage capacities. In general, flow units which correspond to highstand systems tracts with grain-supported facies have enhanced reservoir qualities. These flow units are GF10, GF9, GF8 and GF7, together with the upper parts of GF5 and GF4. The best reservoir quality occurs in flow unit GF9 which is located in the HST of sequence KG3. Flow units GF1 and GF2 from sequence KG1, comprising lagoonal and tidal flat facies, have relatively poor reservoir qualities.     

塔里木盆地北部三叠系辫状三角洲砂体储集层非均质性研究

运用Ｍｉａｌｌ的构型分析法，以库车河地表剖面三叠系黄山街组中部砂体三维构型为模式，将与之成因类型相似的塔北覆盖区三叠系辫状三角洲砂体划分出不同级别的界面和构型单元，并将其非均质性分为４个级别，Ａ级为区域级非均质性，由六级界面控制，延伸范围十几到几十千米以上，宏观上控制了砂体的分布及规模；Ｂ级为亚区域级非均质性，多由五级界面控制，延伸范围几到十几千米，造成同一构造或构造带不同部位油气产能的巨大差异；     

RESERVOIR POTENTIAL OF DEEP‐WATER LACUSTRINE DELTA‐FRONT SANDSTONES IN THE UPPER TRIASSIC YANCHANG FORMATION,WESTERN ORDOS BASIN,CHINA

This paper investigates the reservoir characteristics of deep‐water lacustrine‐delta sandstones in the Upper Triassic Yanchang Formation in the western Ordos Basin, north‐central China. The Yanchang Formation has previously been interpreted as a shallow‐water lacustrine deltaic succession, and this interpretation has been used to guide petroleum exploration activities which have however met with only limited success. The present study integrates thin‐section, wireline log, X‐ray diffraction and SEM data from wells in the western Ordos Basin to determine the sedimentary and diagenetic characteristics of sandstones in the C6 and C4+5 sub‐members of the Yanchang Formation, and to interpret the units' depositional environment. The C6 and C4+5 sub‐members in the study area are composed of: mudstones and fine‐grained sandstones, which are interpreted as deep‐water pro‐delta deposits; laterally‐extensive sand sheets (outer delta‐front deposits); and small‐scale distributary channel and mouth bar sandbodies (inner delta‐front deposits). The sandstones have reservoir potential but diagenesis has had a range of effects on reservoir quality. Compaction together with cementation by calcite and clay minerals including chlorite and kaolinite may have affected pore throat geometry and permeability adversely. However dissolution of feldspars and calcite cement created secondary porosity. Hydrocarbon accumulations may occur in delta‐front channel and mouth bar sandbodies. Core studies show that some sandstone intervals have relatively good reservoir properties with porosity up to 15% and permeability up to 9mD.     

川南河包场构造须二段有效储层地震预测

河包场低平构造上三叠统须家河组二段砂岩生储盖组合良好，油气资源丰富。已有的勘探实践证实，储层品质分布很不均一，只有钻遇有效储层（孔隙度大于8%，单层厚度大于10 m）才可获得工业气流，故有效储层预测是河包场构造须二段气藏描述的关键。为此，运用层序地层学原理及研究方法，将该区须家河组划分为四个地震层序，研究发现须二段有效储层主要发育在层序2的低水位体系域。通过分析层序2低水位体系域的地质、测井、地震等特征，采用地震属性和波形分类技术，确定该层序属于河口坝沉积微相区。同时，通过对层序1厚度的研究，认识了中三叠统侵蚀面岩溶古残丘的分布规律。河口坝沉积微相和侵蚀面岩溶古残丘的分布区域控制了须二段有效储层的分布，在对该有效储层有利区定性预测的基础上，采用高精度地震反演技术完成了对有效储层的定量预测。经钻井检验，预测与实钻吻合，所钻井均获得工业气流。