【作者】 张娟；

【导师】 周文；

【作者基本信息】 成都理工大学 ， 油气田开发地质， 2010， 硕士

【摘要】 鄂尔多斯盆地特低渗油藏普遍无边底水,属典型岩性油藏,其中位于盆地天环坳陷南端的镇泾区块长8油层组即为一个低丰度、特低渗,且平面和垂向上非均质性较强的油藏。镇泾区块的油气勘探评价工作始于1997年,但一直持续到2006年,该区仅在长8油层获大量油气显示,而未试获的工业油流;2007年开始对一批老井进行重复压裂而获得高产,并相继获得了一些高产油流井,从而打开了镇泾区块长8油层组的勘探开发局面。目前在研究区开采过程中仍表现出了地层能量不足,油井投产后日产液量和日产油量下降较快的特征,针对这一情况在ZJ5井区实施先导性注水试验,注水试验总体效果较好,但存在油井见效不均,部分井含水上升快,甚至发生水淹。对于镇泾区块长8油层组这种低产背景存在高产的特点,以及在生产中体现出的非均质性均表明了天然裂缝的发育对油气渗流起到了重要作用。因此研究长8油层组裂缝发育规律以及对生产影响,为下一步开发调整和井网部署提供重要依据。本文通过野外露头裂缝调查及钻井岩心裂缝观察,分析了裂缝类型、产状、裂缝发育密度、有效性等特征。并在此基础上,开展了成像测井裂缝识别,并识别出了连续高导缝、不连续高导缝、连续高阻缝、不连续高阻缝等四种类型裂缝,并对裂缝产状、裂缝特征参数进行了相关计算。通过分析裂缝在常规测井曲线上响应特征,计算了裂缝孔隙度、宽度参数,使用判别分析、R/S分析法、概率神经网络模型等多方法进行裂缝综合识别,最后结合岩心裂缝特征综合建立了基于常规测井的综合裂缝识别标准。在前人对该地区构造演化研究基础上,结合野外调查、岩心观察和测井解释结果,认为研究区裂缝走向主要有NEE-SWW、W-E、NE-SW三个优势方向,主要受到了燕山期和喜山期两期区域应力场的控制,其次天然裂缝的发育也受岩性、层厚、断层等因素的控制。在裂缝平面分布评价的基础上划分三类裂缝区:裂缝发育区、裂缝较发育区和裂缝不发育区。结合生产分析,认为在裂缝发育区,裂缝可以起到良好的导流作用,大规模压裂时,会沿NEE-SWW和NE-SW向的天然裂缝延伸,在后期注水开发中表现出沿裂缝线注水受效快,容易发生水淹,针对以上情况在裂缝发育区应保持注水井与角井的连线平行NEE-SWW走向,放大NEE-SWW裂缝方向井距,减缓角井水淹速度,缩小排距,提高侧向油井受效程度,同时控制注水井的注入压力和注入量,提高驱油效率;在裂缝次发育区,目前注水开发效果较好,油井受效较为均匀,在下步开发中应保持适中注入压力和注入量,维持地层能量,可以适当放大裂缝方向井距,有利于提高压裂规模和单井产量;在裂缝不发育区,注水生产表现出油井见效缓慢甚至不受效,生产井压裂后产液量和产能低,因此在进行裂缝不发育区开发时,应加大压裂强度,增强造缝能力,增加油井泄油面积,在注水时应加大注水压力和注入量,同时适当增加井网密度,改善油井不受效状况。研究区目的层裂缝系统对油藏开发的影响具有双重性,因此在进行开发方案的制定和调整时,应充分发挥裂缝优势,同时避免水淹水窜,从而能真正实现油藏的高效开发。更多还原

【Abstract】 Low permeability reservoirs in Ordos basin generally do not have edge water and bottom water,and they belong to the lithologic deposit.Chang 8 formation of Zhenjing in the south of Tian huan depression is a reservoir with low bearing、low permeability and strong aeolotropism in planar and vertical scale.The exploration evaluation of Zhenjing block started in 1997.Only Chang 8 formation gained plenty of evidence of oil and gas until 2006,and there were not commercial oil and gas flow.Some old wells gained high production because of the use of refracturing in 2007,and some high production wells were drilled.As a result,the exploration and exploitation of Chang 8 formaiton in Zhenjing enter a new stage.In the exploitation,the producing energy is not enough,and daily fluid production rate and daily oil production declined sharply.Pilot flooding tracey is conducted in ZJ5 block,and the overall outcome is good.The effects on the oil wells are not uniform.The water saturation of some wells increase fast.Waterflooding can be seen in some wells.The natural fracture can affect the filtration of oil and gas,because there are aeolotropism in exploitation and discord in outcome.So,the study on fracture developmental discipline and its effect on production can provide significant foundation for the next adjustment of exploitation and well network.This paper use the information of field fractures and the observation of fracuture -s of cores to analyse the fr acuture type、attitude、density and validity etc.The FMI fracture identification is based on the previous work, and continued high electric conductivity fracuture、non-continued high electric conductivity fracuture、continued high electric resistivity fracture、non- continued high electric resistivity fracture are identified.Then,the fracture attitudes and parameters are calculated.Analysing the fractures respond to the conventional log,calculating fracture porosity and width,using the methods of discriminant a nalysis、R/S、PNN,this paper identify the fractures in comprehensive ways.At last,this paper establishes a comprehensive criterion of identification which is based on the conventional log.Based on the previous study of structural evolution about this area,combined with the field investigation、core observation and log interpretation,this paper concludes that the fracture aligements mainly are NEE-SWW、W- E、NE-SW.The aligements are controlled by the Yanshanian and Himalayan regional stress field.The development of natural fractures is controlledby the lithology、bed thickness、fault,etc. Based on the evaluation about distribution of fractures on the plane, the interested area could be divided as three areas, that is, the developed fracture area, the more developed fracture area, and the undeveloped area. Referring to the analysis of producing, this thesis believes that the fractures could play a good role for diversion in the developed fracture areas, and when being fractured, the natural fractures would be extended NEE-SWW and NE-SW. In the later waterflooding,the oil wells along with the fractures are easy to be affected. Because of this,the alignment of input well and corner well should be NEE-SWW, and increase the distance between the wells whose alignments are NEE-SWW.Meanwhile, slow the velocity of the waterflooding, decrease the well array spacing, enhance the response of lateral well,control the injection pressure and injection rate, increase the sweep efficiency. In the area where the fractures are not many, current waterflooding works well,the response of wells are equal. In the next exploitation, app licable injection pressure、injection rate and producing energy should be kept. The interspacing of wells along the fractures should be increased, so the fracturing scale and individual well producing rate will be enlarged. In the area where the fractures does not develop, the oil wells are not easy to be affected in the waterflooding, and the mass production and flow potential of producing wells are bad. Because of this,when the exploitation is made in the area where the fractures are not many, more fracturing should be done in order to enhance the capacity of creating fractures. Increase the drainable area、injection pressure and injection rate, and increase the well spacing density appropriately, change the condition that the oil wells are hard to be affected. The fractures system of the target stratum in the study area has dual effects on the exploitation, so when the adjustment and make of development plan are conducted, the fracture superiority must be utilized, and the waterflooding and channeling should be avoided. The exploitation with high efficiency can be achieved.更多还原