油气层保护、损害诊断(精要版)

1、胡大平：听课人的层次第一层次:“水杯法”，带了水杯，听课时喝得舒服，不记笔记，没有思考，回去后就没有水喝。一时痛快，没有沉淀第二层次:“水桶法”，提一个水桶来，当场喝得过瘾，又记笔记，反思过去，设立目标，准备行动第三层次:“钻机法”，有自己的实践和理论模式，带着钻机来听课，不仅当场喝饱，还学习到了他人的钻井技术，丰富自己的理论。外行看热闹，内行看门道，俗称“偷艺”第五章 油气层损害诊断康毅力 油气藏地质及开发工程国家重点实验室中国石油天然气集团公司油井完井技术中心西 南 石 油 大 学 石 油 工 程 学 院2009年10月21日提 纲0、损害机理及诊断概述1、DST测试2、测井分析3、井史分

2、析4、相邻井生产动态对比5、压力不稳定试井分析6、节点系统分析7、生产效率剖面8、生产测井9、岩心分析油气层损害机理润湿性改变水锁凝析液锁液相圈闭（水，油）气锥或水锥毛管压力的改变乳状液堵塞粘土膨胀微粒运移云母解体无机垢注导致的无机垢酸化引起的二次沉淀碳酸盐溶解沉淀酸渣有机垢石蜡，沥青沉积外来固相的堵塞油气层固相物堵塞，出砂细菌损害应力损害四大类型物理损害化学损害生物损害热力损害损害描述储层损害诊断方法Methods for Recognition of Formation Damage8储层物性条件差饱和度、孔隙度、渗透率、裂缝存在储层损害作业因素,如完井作业中：射孔参数不合理（孔眼密度低、

3、孔眼太小，深度不够，打开不完善）水泥环质量差、强度不高等低产原因损害可能存在的标志压力与产量关系变化波动很大产量低于经济下限产量要比中途测试、岩心分析、测井计算所预测值低得多同一油气藏，储层物性完全相同，但产量差异很大生产井出砂测试时出现表皮效应有机结垢和无机垢沉积注入能力急剧下降，措施或处理周期短诊断技术DST测试分析测井分析生产史分析相邻井产量对比压力不稳定试井分析生产效率剖面生产测井岩心实验分析井下照相井下取样分析节点分析提 纲0、损害机理及诊断概述1、DST测试2、测井分析3、井史分析4、相邻井生产动态对比5、压力不稳定试井分析6、节点系统分析7、生产效率剖面8、生产测井9、岩心分析1

4、、钻柱测试（Drill Stem Tests）In the early stages of exploratory drilling into a new formation, Drill Stem Testing is normally used to confirm the production potential of a hydrocarbon show However, if geochemical analysis of drill chips and cuttings establishes the presence of hydrocarbons, but DST shows

5、the tested interval to be non-productive, then formation damage possibly existsAnalysis of the pressure versus time data generated during DST can be used semi-quantitatively to determine the severity of damage by calculating the skin. It is, however, desirable to exercise caution during initial DST,

6、 since pressure surges and high drawdown can initiate fines movement. Review of prior operational history is then necessary to establish which aspect of the drilling process may have given rise to damage.The following figure shows a typical DST output illustrating a high permeability damaged zone. N

7、otice the following features that are characteristic of damage:Short radius curve along CDE* An almost flat slope along DEA sharp rise after closed-in period as along EFA high differential pressure between a closed-in and final flow pressure (EG)DST Trace Showing Extreme Damage in a High Productivit

8、y Zonept坐封开井关井开井关井开封Exercise in Class1。指出下列测试卡片曲线中，A、B两口井是否存在损害，并说明理由。2。油田开发中哪些作业可以增加渗透率pt曲线A曲线B测井曲线上的泥浆侵入响应Mud Invasion Effects on Well Logs2、测井分析中子孔隙度降低感应电阻率降低The degree and depth of filtrate invasion during drilling can be estimated from deep, medium and shallow resistivity devices (e.g Laterolog

9、) or conductivity devices such as dual induction logs or combinations thereof (e.g Induction-Laterolog). These devices will give semi-quantitative indications of possible damage during production. Analytical models presented by Hassen for describing filtrate invasion can also be used to estimate the

10、 depth of invasion particularly in cases where the depth of investigation of the logging tool is limited.滤液侵入程度和深度可以从深、中、浅电阻率测井或双感应测井曲线进行半定量评价If problems are identified by DST and logs, further investigation is still necessary to pinpoint what aspect of the drilling/completion program is responsible

11、 for the apparent poor formation response作业史分析 Daily drilling/ cementing/completion reports, mud and completion, workover andwell stimulation fluid programs should be reviewed (Allen). 滤失量、pH值、钻速随深度变化Fluid loss, pH and ROP data shouldbe plotted as function of depth to help identify any zones where h

12、igh pH-filtrate loss had occurred. Such zones are good candidates for damage.An individual well analysis then quantifies whether or not the well is producing topotential. If not, why? And the production potential behind pipe.3、井史分析（Well History Review）The production potential of an ideal well in a f

13、ield, pool or lease is evaluated, while recognizing that the well potential will depend on the following factors:Type of drive mechanismStatus of depletionRock and fluid properties (Kh, qh, 1L, Krel, PVT, etc.)The productivity index (PI) is typically computed for unbounded and bounded reservoirs fro

14、mDarcys Law for Steady State Incompressible Flow as follows:Comparison of theoretical to actual production rates can be used to establish whether or not the well is producing at exptected capacity, for the given operating drive mechanism as shown on Figure 5-4A and B.Actual vs Theoretical Specified

15、Productivity IndicesProduction History Showing Well Damage Problem提 纲0、损害机理及诊断概述1、DST测试2、测井分析3、井史分析4、相邻井生产动态对比5、压力不稳定试井分析6、节点系统分析7、生产效率剖面8、生产测井9、岩心分析When a well experiences an abnormal gradual decline in productivity as compared to other wells penetrating the same formation with similar initial tran

16、smissibility (Kh) values, formation damage can be suspected. Analysis of semilog plots of production rate versus time data forthe candidate well and an offset well can be used to compare their relative productiondecline rates. If the candidate well shows a higher decline rate, then the existence of

17、formation damage is most likely.Figure 5-8 shows a candidate Well B penetrating a similar zone as an offset Well A, but exhibiting a higher decline rate than Well A as shown on Figure 5-9.4、相邻井生产动态对比Comparison of ProductionPerformance of Offset WellsComparison of the production performance of Wells

18、A and B can also be accomplished bycomputing their respective theoretical and actual specific productivity indices (SPI) as follows:Problem 5-2 illustrates the use of SPI for comparative evaluation of the productionperformance of two offset wells in a given lease.提 纲0、损害机理及诊断概述1、DST测试2、测井分析3、井史分析4、相

19、邻井生产动态对比5、压力不稳定试井分析6、节点系统分析7、生产效率剖面8、生产测井9、岩心分析Extensive body of literature exists on the use of well test analysis for diagnosis of damagedformations (Miller et al.; Horner; Hurst; Van Everdingen; Thomas;, Nowak et al.; Matthews et.al.; Mcleod et al.; Earlougher).Pressure transient well test analys

20、is is perhaps the most effective field technique fordetection of formation damage. Buildup and drawdown tests can be used to establish the existence of formation damage particularly in wells with a high productivity index. Analysis of the test data by any appropriate technique (Horner, Gringarten et

21、 al.; Bourdet et al.) canyield a damage skin factor, S defined by Hawkins. The skin factor is a composite of two skins- one due to damage, S1 and another, S2 due to restricted entry into the wellbore caused by mechanical factors.5、压力不稳定试井分析 Pressure Transient Well Test AnalysisThe skin due to mechan

22、ical factors can be computed by the methods of Brons et al. And Odeh. The skin due to damage, S1 is a cumulative effect of damage from the various operations. Thus, pressure transient analysis is still handicapped by not being able to identifyat what stage of well development the damage occurred.Bui

23、ldup and/or fall-off tests are useful for evaluation of the damage and stimulation potentialof any well.理想的油藏模型Pw (th + t)/t 曲线压恢与压降测试分析关井后理论与实际的井底压力动态压力恢复压力降落The skin factor, S can be computed from a build-up or fall-off curve as follows:where:Pw1hr=Pressure on the straight line portion of the buil

24、d-up or fall-off curve at a shut-in time of 1 hourk=bulk formation permeability, md=porosity, fraction=viscosity, cpc=compressibility, psi-1表皮系数与附加压降表皮系数S与损害带渗透率和深度有关式中：Kd损害带渗透率K地层原始渗透率rd损害带半径当 SD0 ，储层可能被损害，因 Kd K SD KRd 需要通过其它手段确定，如测井和模拟实验Kd 可由 K, rd 和 S 通过下式计算：损害带半径和损害带渗透率的测定The additional pressur

25、e drop incurred in the near wellbore region due to the presence of a damaged area, rd, is given by:(P)s=141.2 qB/kh SD=141.2 (m/162.6) SD(P)s=0.87 ms(P)s is the change in the following bottomhole pressure if th altered zone permeability, kd, was equal to the bulk formation permeability, kFor a new r

26、eservoir where pressure transient has not reached the true boundary:re = =0.00633 (K/c)th=Horner Time = 提 纲0、损害机理及诊断概述1、DST测试2、测井分析3、井史分析4、相邻井生产动态对比5、压力不稳定试井分析6、节点系统分析7、生产效率剖面8、生产测井9、岩心分析并不是所有的表皮系数都是由储层损害引起的S损害=S总-S拟完井设计或井下管柱结构不合理导致拟表皮系数限制流入：紊流，裂缝与井筒斜交偏心井射孔孔密、孔深、相位不合理机械节流举升系统不匹配：油管径小，气举阀不合理，地面回压高薄互层

27、油藏井斜6、节点系统分析Nodal Systems AnalysisNodal analysis has evolved as a powerful tool for detection of formation damage and evaluation of effective stimulation procedures. As defined by Brown et al., nodal analysis is a systems approach to optimization of oil and gas wells by thorough evaluation of thecom

28、plete producing system. Mcleod referred to this method as Well Flow Analysis in that each component of the well system is checked to determine its contributions to any flow restrictions.自喷井系统中的各种压力损失泄流边界 井筒（射孔孔眼）井口与油嘴分离器储罐气藏油管管线输送管线压力PePwfPwhPspPsTrh气井压力剖面The procedure for developing the Inflow Perf

29、ormance Relationship, IPR, (sand face pressure versus rate), Tubing Intake Curve (bottom hole tubing pressure versus rate), Differential pressure available for any rate across the completed interval, and the pressure drop across the completion for various rates have been documented by Mcleod. The pr

30、essure drop across the completion varies with the following completion parameters: length of perforated interval, perforation diameter, length of perforation tunnel, and permeability of the tunnel. Figure 5-14 shows a typical nodal analysis curve which permits determination of optimum production rat

31、es for various wellbore mechanical considerations. When the predicted and actual performance of the oil or gas well are compared, it is easy to establish that the well is not producing at capacity and that formation damage may be present. Nodal Analysis Curve Relates Production Rate to Bottomhole Pr

32、essure (BHP) or Change in Pressure (P). Optimum Production Rates are shown for various perforation densities (SPF)压力产量曲线lbesn developed a production efficiency pro for evaluation of well performance.This technique is analogous to Nodal Analysis. However, the technique relates the radius of possible

33、damage to what the author calls incremental pore volume, IPV and incremental fluid velocity, IFV. The radius from the wellbore to any zone of the reservoir is plotted asfunction of both IPV and IFV. The point of intersection of the IPV and IFV profiles defines a particular critical radius, Rci for i

34、nitial reservoir production and initial pressure, Pi. If the current production is used to compute a new IFV profile, the new intersection of IFV with IPVwill define Rc2 for current pressure, P2. If the ratio of Rc2/Rci P2/Pi,the well is operatingabove optimum, if Rc1/Rc2 = P2/Pi, the well is operat

35、ing at optimum rates and if Rc2/Rcl P2/P1, then the well is producing below optimum and is possibly damaged.Figure 5-15 shows a schematic of a cylinderical shell around the wellbore which illustratesthe concept of production efficiency profile (PEP).7、生产效率剖面Production Efficiency ProfileThe pore volu

36、me, Vpi, at a radius, RI (inches), from the wellbore is given by:At a radius, R2, where R2 = R1 + 1 inchIncremental pore volume (IPV, Vp within the one inch by one foot shell is given by:提 纲0、损害机理及诊断概述1、DST测试2、测井分析3、井史分析4、相邻井生产动态对比5、压力不稳定试井分析6、节点系统分析7、生产效率剖面8、生产测井9、岩心分析生产测井可以作为诊断损害的补充手段生产测井的基本功能是追踪套

37、管内及套管外 流体运动，监测流体接触界面的运动情况 生产或注入流动剖面用于确定各个射孔层段流量的分布， 以判别某个层是否存在损害 技术应用转子流量计（Spinner Flowmeter ）流体密度计（ Gradiomanometer ）8、生产测井（Production Logging） The spinner flowmeter is used to measure fluid velocities in the tubing or casing(Figure 5-16). The tool is centrally located within the fluid column and m

38、oved at aconstant speed against the direction of flow. The spinner speed is linearly relatedto the fluid velocity relative to the tool and recorded continuously as function ydepth. A typical spinner tool is the continuous flow meter which is useful for determination of production and injection profi

39、les, analysis of fracture or acidizing jobs for evaluation of productivity index.8.1 转子流量计（Spinner Surveys）After McKinleyAfter McKinleyThe gradiomanometer tool is designed to determine the changes in pressure gradient. This tool is useful in high flow rate wells and is well-suited for pro in two pha

40、se flow. This tool measures the pressure difference in the well between any two points and if frictional losses are negligible, then the pressure difference is equal to the hydrostatic pressure gradient, due to the average fluid density in the pipe over the investigated interval.8.2 流体密度计Gradiomanom

41、eter SurveyHold-up Determination from Grandiomanometer Data8.3 其它方法温度测井井下电视井壁取样分析提 纲0、损害机理及诊断概述1、DST测试2、测井分析3、井史分析4、相邻井生产动态对比5、压力不稳定试井分析6、节点系统分析7、生产效率剖面8、生产测井9、岩心分析All the field techniques discussed so far can identify the probable existence of damage but none can either pinpoint at what operational stage the damage may have occurred and/or quantify the relative contribution to damage from various well operations.However, laboratory testing of the fluids and techniques used in various well operations will help decipher not only the pot