渤南一区浊流储层特征-断块油气田

渤南一区浊流储层特征许金慧1,2　史桂生2　彭海军3(11长江大学地球科学学院　21中原油田分公司采油一厂　31新疆石油公司试油处)摘　要　渤南一区储层砂体发育典型的低密度浊积序列,形成完整和不完整的鲍玛序列。

该区砂体中辨识出砂体和泥质十种岩石相、九种岩相组合的基础上确定出浊流沟道、沟道间、席状浊积体和滑塌体等4种浊积砂体类型,总结了各砂体和测井响应特征。

依据砂体类型和展布特征可将砂层分为3种类型:沟道型、席状浊积体型和滑溻体型。

夹层的分布具有明显的层次性,层间夹层具有厚度大、展布广的特征,而层内夹层则进取度小,展布相对局限。

关键词　沉积微相　浊积砂体　非均质性　渤南油田 浊积岩早已为沉积学者所认识,并一度受到重视,成为地学研究的热点,现已形成了较为成熟的海底扇相模式、湖底扇相模式等相模式[1～4]。

还应用储层建筑结构分析和层序地层学的观点对浊积地层进行了讨论[5]。

然而对于低密度浊流所形成的浊积岩的储层非均质特征在国内的研究还较少,对渤南一区沙三段储层进行了研究,认为其发育为典型的浊积层序,应为低密度浊流。

Ξ渤南油田构造上属于济阳坳陷沾化凹陷东北部的渤南洼陷,东为孤岛凸起,南与罗家油田相邻,西部与四扣向斜相连,北面以呈南断层为界与埕东凸起相接,范围600km2。

该区南北两面被两条近东西向的断层切割,断层北倾,倾角40～60°,断距80～100m,地层西高东低,区块南北部分别有一个局部高点,中间为一向东倾伏的低槽;该区含油层系为沙二段、沙三段两套含油层系9个砂层组,主力油层沙三2、沙三3。

1　岩石学特征7口取心井的观察表明,渤南油田岩心有以下特征:①总体上是大套深灰色厚层湖相泥岩夹相对较薄的砂岩沉积。

②砂岩粒度细,主要为细砂岩,其次为粉砂岩和中砂岩,砾石一般为同生未完全固结的泥砾,其它成分砾石较少见,泥砾常见撕裂状,显为冲蚀而成。

源于三角洲前缘的再滑塌沉积于前缘斜坡及深湖平原。

③沉积构造类型十分丰富,常见块状层理、递变层理、平行层理、波状斜波状层理、重荷、砂球、砂枕构造、包卷层理、泄水构造和砂岩脉及滑塌变形构造。

其特点是:浊积岩构造齐全,且滑塌变形构造丰富。

④岩石颗粒分选大都较差,个别中等;概率曲线上为一段式或两段式,CM图上,分布区与C=M大致平行,具有明显的浊流特征。

⑤岩石组合为典型的鲍玛层序,完整单一韵律构成依次为:底面的侵蚀冲刷面,向上变为递变层理的中细砂岩,然后是平行层理粉细砂岩,再上是薄的粉砂与泥互层的水平层理段,最上则是厚度不一的深湖相泥岩。

这些现象说明该区储层属沉积速率较低的深湖相沉积背景下的浊流沉积砂体。

2　测井响应特征该区地层测井响应研究进行了两方面的工作,一是依据测井响应判定沉积相,二是依据测井响应进行地层对比。

研究发现仅有自然伽马和自然电位能反映砂体微相特征,而感应电导率旋回特征明显,可用来确定地层旋回,进行储层对比。

沟道微相自然电位曲线显明显的高负异常,自然伽马显示低值,表明其泥质含量较低。

微电位曲线一般都有明显且稳定的幅度差,显示出具有良好的渗流特性。

测井曲线形态上以箱形、钟2004年11月断块油气田FAUL T2BLOCK OIL&GAS FIELD第11卷第6期Ξ收稿日期　2004-04-19第一作者简介　许金慧,女,1970年生,长江大学2002级在读硕士研究生,现从事培训教学工作,地址(457172):河南省濮阳市,电话:(0393)4851249。

形为主,个别为倒松塔形。

其中箱形曲线一般为沟道中心部位沉积,撮度大,物性好;靠近沟道侧缘部位则大都表现为钟形,而位于沟道末稍部位的砂体则更多地表现为倒松塔形,显示出沟道的向前推进。

沟道间自然电位为较低的负异常,自然伽马显低值。

与沟道明显不同的是沟道间在自然伽马曲线上常表现为多个低值峰的组合,表明其沉积是由多期完成的,而在砂体沉积间期则沉积湖相细粒沉积物。

其微电位曲线幅度差不稳定,表明其内部非均质性较强。

曲线组合形成上,多表现为利复合钟形或复合倒松塔形。

席状浊积砂自然电位显示微弱的负异常或无异常,自然伽马显低值,微电位显示较小的幅度差,表明其物性较差。

曲线组合为指形或复合指形。

深湖泥主测井曲线形态为平直状,自然电位为基值,电阻率曲较小,但感应值变化较大。

滑塌透镜体在曲线形态上多为箱形或倒松塔形,由于混有大量的泥砾,自然伽马曲线值相对沟道较高。

3　储层对比和储层结构311　储层精细对比渤南一区测井曲线研究表明,感应电导率曲线标志明显,能够明确反映地层旋回。

对比中以电导率曲线为主,综合利用自然电位、自然伽马、微电阻率等测井曲线,按“旋回控制,逐级对比”的原则进行。

该区地层不同部位地层的发育程度差别很大,而在南缘和北缘部位,地层发育较为完整。

因而在对比时,选择南缘的11-37井为南缘的标准井,北缘则选择11-33井为对比的标准井,先从两侧对起,逐步向中间推进,最终完成对比。

岩电关系特征,对比时遵循以下原则:识别标志层,把标志层作为对比的基点;该区地层旋回性明显,标志层清楚,基本上可以准确地用标志层卡准沙三顶部和沙三0、1和2砂层组的顶界,但沙三2底界及以下地层则缺乏标志层,要靠砂体的旋回性进行对比。

建立对比剖面的目的是为了方便对比和检验对比的正确性,最好是建立的对比剖面能够反映出砂体的展布特征,一般来说,在沉积走向和沉积倾向方向砂体的特征差别较大,所以建立的对比剖面一般沿沉积走向和垂直沉积走向呈十字交叉状为好,另外建立的对比剖面最好能够覆盖全区,便于对比时以剖面为中心逐步推开。

据以上原则,在渤南一区选择南北向对比剖面和东西向对比剖面各四条(见图1),基本上是平行和垂直沉积走向的(由于部分井没有数字化测井数据,故而影响了剖面的建立,而在形成的对比剖面图中,个别井也因此原因而未做图)。

图1　剖面Ⅶ-Ⅶ’砂体和相展布312　储层结构特征该区砂层内部部连通性较差,尤其是非主力层,砂体多为孤立状展布,但不同层位其特特又有所不同(见表1)。

按砂层内砂体类型及其展布特征可分为3种类型:①浊流沟道型,该类型平面上以浊流沟道为主,沟道间充填厚度较大的沟道间砂体,砂体整体上厚度大,物性好,砂体之间连通性较好,注采对应性好,易于开发动用,如沙三段22砂层,钻遇该砂体井数达95口,砂体钻遇率达77%,最大厚度达1512m ,平均厚度为519m ,第11卷第6期 许金慧等1渤南一区浊流储层特征 2004年11月沟道面积占整个砂体面积的一半上下。

②席状浊积砂型,主要以薄层的席状浊积砂为主,物性差,大部分为干层或差油层,如02砂层区内钻遇井数68口,钻遇率55%,最小厚度014m,最大612m,平均2101m。

砂体主要分布于一区的中部和东部,发育有沟道,但浊流沟道规模较小,而且相互之间并未相互切割叠置,从而表现出相互不连通,呈独立分布的格局。

③滑塌透镜体型,以厚度较大,展布面积较小的滑塌体为主,个别部位物性好,但规模有限,连通性较差,砂体难于完善注采关系。

如沙三51砂层,其最大厚度达16m,但最小仅014m,钻遇率低,只达24%。

表1　典型砂体展布特征砂层类型典型砂层钻遇井数/口厚度/m最小最大平均钻遇率席状浊积砂型026401451921220152沟道型229501515125190177滑塌型51290141641160124313　储层砂体非均质性特征31311　储层层间非均质性特征砂层之间的非均质性较强,02层平均空气渗透率15×10-3μm2,孔隙度2214%;22层平均空气渗透率157×10-3μm2,孔隙度2314%;3砂组平均空气渗透率为46×10-3μm2,孔隙度2312%,渗透率级差达3～10。

31312　隔夹层分布特征本次研究对两个层次的夹层进行了研究:一是砂层组间夹层,一是砂层组内小层之间的夹层。

对钻遇井夹层统计表明,砂层组间的夹层规模远较砂层组内的夹层大,单层厚度多在5m以上,而砂层组内的夹层则较小,厚度多在5m以下,以2～4m为多(见表2)。

砂层组间夹层厚度大于20m的占钻遇井数的近35%,15～20m占20%,10～15m占1214%, 5～10m占21%,而5m以下的仅占11%多一点。

尽管如此,各砂组之间的夹层还有所差异。

砂层组内夹层以1～5m为主,总体上2～5m占钻遇井数的35%,1～2m的占31%。

表2　砂层组间夹层分布特征夹层厚度/m钻遇井数/口0～11～22～33～44～55～6夹层>207132282011515～20340910326710～153********5～10035273570≤5242342338合计798692382115331 4　结论与建议(1)渤南一区储层低密度浊流砂体,发育比较完整和典型的鲍玛序列,其储集砂体包括沟道砂体、沟道间砂体、席状浊积砂体和滑塌体等。

(2)不同时期浊流砂体分布特征不同,导致其不同的非均质特性。

该区砂层分为3种类型:沟道型、席状浊积砂型和滑塌型,沟道型物性好、展布广,为主力砂层,席状浊积砂物性差,滑塌型分布局限,对产出贡献较小。

(3)不同类型砂层展布特征和物性的差异必将导致开发响应不同,建议针对不同层的砂体类型进行开发调整,以提高采收率。

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The comparison of the results of analytic solution and numerical inversion shows that,the calculation accuracy is within5percent,and thus it can be applied to the engineering.K ey Words:Tight gas reservoir,Start2up gradient,The solution in the Laplace space,Analytical solution.R esearch and Application of Fracture for the Middle Es3R eservoir in N orthblock Wen13Shi Mingjie(The N o.1Oil Production Plant, Zhongyu an Oilf ield Company,SIN OPEC,Puyang457071, China),H an H ongxia and Zhang H ui et al.F ault2B lock Oil &G as Field,2004,11(6):35～36G enesis,characteristic and distribution rule of the northblock wen13in Wenliu oilfield fracture are introduced in this paper.The fracture’s distribution characteristic is quantitativety calculated.With combining the structure fracture,reservoir physical property and dynamic datum, analysis the rule of the oil2water motion and the rationality of injection2production well pattern.The reliable basis are offered for block waterflood development and enhancing oil recovery.It will be very much helpful to develop the similar oilfield.K ey Words:Fracture,Distribution rule,Main curvature method,Sand member,Restraining mass,Waterflood.Study of Development Methods on Pucheng Oilf ield in Extra2high2w ater2cut StageG u Daihong(G as E ngineering I nstitute of Petroleum U niversity,B eijing102249,China),H e Shunli and Tian Leng et al.F ault2B lock Oil&G as Field.2004,11(6):37～39The steady production lies mainly in the deep knowing or re2knowing,for the residual oil,in the Extra2high2water2 cut stage oilfield.Pu53block reservoir has entered into the extra2high2water2cut stage,oil production decreases,and water2cut increases rapidly,thus adapt ability is poor in injection2production system.A numerical simulation is conducted in the reservoir on the basis of precisely building a geologic model.Production performance fitting is implemented,and the law of distribution of remaining oil is derived.Based on the current production situation and problems existing in the oilfield,projects for enhancing oil recovery are proposed and the prediction is made,which is the guidance for actual production of the reservoir to a certain degree.After the stimulation of potential production is implemented,oil production enhancement is obvious.The result demonstrates that it could be used for the development of similar oil reservoirs.K ey Words:Pu253fault block,Extra2high2water2cut stage,Oil2water distribution,Saturation map,Researching projects.The R esearch Model on Distribution of R em aining Oil in Multi F ault2B lock R eservoirs with High W ater2cut Su Biaojin(I nform ation C enter,Zhongyu an Oilf ield Company,SIN OPEC,Puyang457001,China),H e G u anjun and Li Lianmin1F ault2B lock Oil&G as Field,2004,11(6): 40～42According to the facts of multi fault2block reservoir and its characteristics,a new research model,synchronous research model was achieved.The new model was implemented in the Block2101of Zhongyuan Oilfield,and the distribution of remaining oil in this block was studied.The new research model got over the lack of communication during studying,enhanced the cooperation amongVol.11　No.6 ABSTRACT NOVEMBER2004。