通过岩心观察、铸体薄片鉴定、粒度分析及分析化验资料等,对6口井的岩心资料进行分析,游园沟油田下油砂山组N21油藏,储层岩性主要为细砂岩、粉砂岩和极细砂岩.砂岩储层下油砂山组N21油藏主要为三角洲前缘沉积砂体,单层厚度薄、层数多,碎屑岩储层占总厚度比例约30％,单砂体厚0.9-4.8m,平均2.3m;砂岩储层的成分成熟度中等、结构成熟度差别大,压实强度较弱,储集性能主要受填隙物含量、孔喉结构等因素控制.

近年来随着水平井技术的突破性进展,钻井综合成本的逐年下降以及经济效益的显著提高,水平井在不同油气藏开发中都得到了广泛的应用,目前砂西区块E31油藏仅开始水平井试验阶段.本文在充分论证砂西E31油藏水平井钻探适应性的前提下,通过2口已钻水平井的实例分析,认为油藏具有水平井开发提高单井产量及开发效果的潜力,进而对该区水平井设计原则及井眼轨迹控制方法进行了充分的论述,在部署水平井时要充分了解储层地质特征,从井位论证、设计到施工整个过程都要做好工程与地质的密切配合,及时掌握各类地质信息,综合分析、准确判断,确保地质钻探的成功.

The formation of tight gas is controlled by the low porosity and permeability of sandstone reservoirs .It has been recognized that the accumulation of pervasive low abundance tight gas is possible only when the porosity and permeability of reservoir is above a certain limit value .However , there are no widely accepted criteria for defining this limit value . Based on collection of the measured reservoir property of both domestic and international typical tight gas sands ,we stu-died the statistical distribution patterns of permeability and porosity of tight reservoirs ,and analyzed the causes for reser-voir tightening and the characteristics of tight gas accumulation .Data show that over 80%routine permeability data points have a permeability less than 0.1 ×10 -3 μm2 .The corrected in-situ permeability is about one order of magnitude lower than the routine permeability .Taking the routine permeability value of 0.1 ×10 -3 μm2 as the upper limit of tight gas sands is reasonable and practical .Statistics of tight gas sands over the world shows that tight sandstone reservoirs have di -versity of sedimentary environments ,large depth span ,and long time range in geological age .Tectonic activity ,sedimenta-ry environment and diagenesis are the main factors for the formation of tight reservoir ,but they play a different role in dif-ferent basins .The distribution of tight gas sands can be delineated by analyzing source rock ,tectonic movements and rese-rvoir tightness .

油砂山油田是一个复杂断块油田,断裂主要发育NE向正断层;受断层影响及形成褶皱不均匀应力的影响,构造轴线发生偏移,在不同的断块轴向发生变化,构造被一系列正断层及少数逆断层复杂化,形成局部的断垒、断堑及阶梯式下滑形态.油田划分为6个断块;本次研究利用测井二次解释成果,结合地质研究新认识,在纵向上划分为13个油组211个小层,5632个油砂体,分别从油砂体储量、面积、控制井数,沉积微相,构造与断层,油水连通关系等方面对油砂体特征进行研究,对油田的油砂体储量规模和储量分布状况进行了综合评价,为下步开发部暑提供科学依据.

油砂山油田是青海油区的一个老油田,自1956年投入生产以来,已开发生产57年,累计生产原油166.75万吨,通过对油田近年来的注水开发指标分析,认为油田目前注采系统还不能完全适应油田油砂体的分布状况,油水井井距偏大,油水井数比偏大,多向受效率低,油水井连通性差,水驱控制程度低等矛盾。有必要通过调整方案完善和优化油田注采系统,提高储量动用程度,提高注水利用率,改善油田开发效果,提高采油速度及最终采收率,实现效益开发。

Based on high resolution sequence stratigraphy theory,and through the comprehensive study of outcrops,cores,drilling and logging data,the authors studied in details the strata division and contrast for lower Youshashan Formation in Youshashan oil field in Qaidam Basin. Single well sequence stratigraphic framework was established in accordance with the regional stable beds identified by logging curves,and based on the single well sequence stratigraphic framework,two directions were chosen approximately parallel and perpendicular to the provenance in the study area,so as to make connecting-well contrast of dense well network and establish high resolution sequence stratigraphic framework in the study area. Taking short-term and ultra short term cyclic sequences as contrasting units in the isochronous stratigraphic framework,the authors studied the distribution of sand bodies,the development and evolution of sedimentary facies in the stratigraphic framework,thereby that will be beneficial to the reservoir prediction and the late exploration of the oilfield.

油砂山油田是一个复杂断块油藏,有大小断层35条,其中正断层32条,逆断层3条,断层分布在整个背斜构造,油田按主要断层走向划分为6个断块.油田平面上沉积微相变化快,储层岩性和流体性质差别较大,平面非均质性严重;纵向上含油井段长(300～500m)、油层层数多、单层厚度薄,纵向共划分13个油组211个小层.2011年油田通过细分层系注水开发,取得了一定成效,但油田注采连通率依然较低、水驱控制程度、水驱动用程度、开采程度都较低,综合含水上升快,单层突进加剧,层间矛盾仍然比较突出等问题,油田具有进一步挖潜的潜力.

砂西E31油藏经过长期开发,油藏面临油水井数比高、采出程度低,单井自然产量低、递减快,开采效果差的突出问题.为了改善开发效果,提高难采储量动用程度,在充分论证油藏开发潜力的基础上,通过精细构造解释,储层特征研究、测井二次解释、剩余油分布研究,提出了井网加密调整、油井转注、油水井措施为一体的综合调整方案.经现场实施,取得了较好开发效果,预测最终采收率较标定采收率提高2.3个百分点.

In the light of the high-resolution sequence stratigraphic theory presented by Cross,and well logs and core observation in this study,the strata of the Upper Ganchaigou Formation in the Youshashan Oil Field,Qaidam Basin,Qinghai may be divided into 15 to 20 short-term,6 medium-term and 1 long-term base-level cyclic sequences. The present paper focuses on the analysis of sedimentary facies and evolution within the individual cycles,construction of the high-resolution isochronous stratigraphic framework in the ascending and descending hemicycles of the medium-term cycles and sandstone distribution in the Upper Ganchaigou Formation. It is indicated that the early ascending hemicycles,late descending hemicycles and the delta system are interpreted to be the most favourable zones for the development of reservoir sandstones.

油砂山油田于1956年钻浅1井获得成功并投入试采开发,到目前已勘探开发生产50余年,为了进一步挖掘油砂山油田潜力,解决油田开发中存在的问题,有必要进行更精细的油藏地质研究,建立数字化、定量化、多维可视化的数字地质模型,为下步储层建模与数值模拟提供更精准的地质基础。

油藏进入高含水期后,剩余油的分布呈现高度分散、局部富集的特点,常规的剩余油潜力分布定量化表征方法在难以准确刻画潜力区域、制约了剩余储量挖潜措施制定。考虑到剩余油分流能力与含水饱和度之间的非线性关系,本文引人优势储量丰度表征剩余可采储量分布。在精细油藏数值模拟基础上,刻画出该油藏剩余油储量优势丰度分布,并结合其他剩余油研究方法,制定了油水井下步调整挖潜措施,通过在油藏近2年实施,取得了与剩余油储量优势丰度一致的效果,印证了该方法的有效性,为同类油藏高含水期剩余油研究提供了一种方法。