井间剩余油电磁探测理论和方法研究

发布时间：2018-07-27 18:16

【摘要】：目前,我国油气勘探新区逐年减少,对油气的勘探逐渐转向老区勘探,即对老油区的剩余油进行二次开采。老油区的生产井中都有套管,因此研究老油区套管井井间剩余油的探测理论和探测方法具有重要的意义。本文针对油气生产井的实际工作环境与特点,研究了井间剩余油电磁探测的基础理论、方法及关键技术。在国家自然科学基金项目的资助下,对井间剩余油电磁探测技术进行了理论研究、建模仿真、室外实验研究。主要研究工作如下：(1)将套管看作是线源,即利用一口井的套管作为发射线源,并对套管直接施加一定频率的交变电流,用另外一口井的套管作为接收线源,测量接收井的感应电动势。系统研究了垂直线源的场,以及发射套管施加的电流大小、频率、地层电导率、井间距离的变化对接收套管上产生的感应电动势信号的影响规律,并给出了图形化描述。结果表明：接收套管接收到的信号随着发射套管上施加电流的频率的增大而减小,随着套管间距的增大而减小,随着地层电导率的增大而减小,随着发射电流的增大而单调递增。(2)在两口套管井内部各布置一个探头(铁芯缠绕一定匝数的导线),给其中一口井套管内的探头施加一定频率的交变电流作为发射端,另一口套管井内的探头作为接收端,观测接收探头上产生的感应电流密度模。研究了发射线圈施加电流大小、频率、地层电导率以及套管间距的变化对接收线圈上产生的感应电流密度的影响规律,并给出了图形化描述。结果表明：随着发射电流的频率增大,接收线圈上产生的感应电流密度模逐渐呈递减趋势；随着发射电流幅值的增大,接收线圈上产生的感应电流密度模呈明显的递增趋势：介质的电导率位于10S/m时,接收线圈所接收到的感应电流密度模最大；随着井间距离的增大,接收线圈上产生的感应电流逐渐减小。(3)在裸眼井内布置一根铁心缠绕两组线圈,一组线圈作为发射线圈,另外一组线圈作为接收线圈。给发射线圈通以一定频率的交变电流,接收线圈接收来自发射线圈的发射电流和地层耦合之后的总电流。根据接收线圈上产生的感应电流密度模来分析地层的基本信息。结果表明：随着井间距离的增大,接收线圈接收到的感应电流密度模呈现微弱的递减趋势；地层电导率变化对接收线圈上接收到的感应电流密度模没有显著的影响,分析原因可能是线圈距离过近导致；接收线圈接收到的感应电流密度模随着发射线圈施加的电流呈递增趋势；接收线圈随着发射线圈施加的电流频率的变化没有呈现显著的变化趋势。(4)基于安培定律和电磁波传播理论,研究套管自身对点电流源的响应特性,分析了点电流源和套管距离、两电流源距离、套管半径对套管上电流密度的影响。结果表明：套管和点电流源距离越近,套管上的电流密度越大,且套管上电流密度最小值的位置点越接近点电流源所在处的位置；套管中电流密度最小值的位置点所在处是由点电流源所在处的位置决定的；套管半径越小,电流密度的幅值变化就越大,其上的电流密度的幅值也越大。(5)井间有剩余油和没有剩余油时,井间的电流密度分布规律不同,井间无剩余油时套管轴向的电流大部分都集中在套管上端部分,即套管上端部分的电流线较密；井间有剩余油时,套管轴向电流在套管上端和两侧都较密集。当井间存在剩余油时,套管间均匀选取的点的电流密度模明显小于井间不存在剩余油时套管间均匀选取点的电流密度模。当均匀选取和套管轴向平行的点计算电流密度模值时,若套管间存在油层,即该处的电流密度模值将明显小于其他的点。(6)试验研究：用一口井的套管作为发射线源,另外一口井的套管作为接收线源,通过不断的改进和总结共进行了多次大型户外试验,验证了基于线源的井间剩余油电磁探测收发系统的可行性。最终得出结论：导线暴露在空气中,应该给导线套上屏蔽线,以减少外界干扰；需要增加低通滤波器来获得较大的感应信号。
[Abstract]:At present, the new area of oil and gas exploration in China is decreasing year by year, and the exploration of oil and gas is gradually turned to the old area exploration, that is, the remaining oil in the old oil area is two times. Therefore, there are casing in the production wells in the old oil area. Therefore, it is of great significance to study the exploration theory and detection methods of the remaining oil in the casing wells in the old oil area. The basic theory, method and key technology of the residual oil electromagnetic detection between wells is studied. Under the support of the National Natural Science Foundation project, the theoretical research, modeling and simulation, and outdoor experimental research are carried out on the interwell residual oil electromagnetic detection technology. The main research work is as follows: (1) the casing is regarded as a line source, that is, profit The casing of a well is used as the source of the transmission line, and the alternating current of a certain frequency is applied directly to the casing. The induction electromotive force of the receiving well is measured with the casing of another well as the source of the receiving line. The field of the vertical line source is studied systematically, the current size, the frequency, the conductivity of the formation and the distance between the wells are received. The results show that the signal received by the receiving casing decreases with the increase of the frequency of the current on the tube, decreases with the increase of the spacing of the casing, decreases with the increase of the conductivity of the formation, and increases with the increase of the electric current. (2) a probe is arranged inside the two casing wells (a conductor winding a certain number of turns), and an alternating current of a certain frequency is applied to the probe in the casing of one of the wells as the launching end, and the probe in the other casing well is used as the receiving end to observe the induction current density mode produced on the receiver probe. The influence of current size, frequency, formation conductivity and the variation of the spacing of the casing on the induced current density on the receiving coil is described and a graphical description is given. The results show that the induced current density mode on the receiving coil gradually decreases with the increase of the frequency of the transmitting current; with the amplitude of the emission current, the amplitude of the current is gradually reduced. When the conductivity of the medium is located at 10S/m, the induced current density mode received by the receiving coil is maximum. With the increase of the distance between wells, the induction current produced on the receiving coil decreases gradually. (3) a core is arranged in two groups in the naked hole well. A coil, a set of coils as a transmitting coil and another group of coils as the receiving coils. The alternating current of a certain frequency is passed to the transmitting coil, the receiving coil receives the transmitting current from the transmitting coil and the total current after the formation coupling. The basic information of the formation is analyzed according to the induced current density mode produced on the receiving coil. It is shown that with the increase of interwell distance, the induced current density mode received by the receiving coil presents a weak decreasing trend, and the change of the conductivity of the formation has no significant influence on the induced current density modes received on the receiving coil, and the analysis may be caused by the close proximity of the coil distance; the induced current density mode received by the receiving coil. With the increasing trend of the current applied by the transmitting coil, the change of the current frequency of the receiving coil does not show a significant change. (4) based on the Ampere law and the theory of electromagnetic wave propagation, the response characteristics of the casing to the point current source are studied, the point current source and the distance of the casing, the distance of the two current source, and the sleeve are analyzed. The effect of the tube radius on the current density on the casing shows that the closer the distance between the casing and the point current source is, the greater the current density is on the casing, and the position point of the minimum current density on the casing is closer to the position of the point current source; the location of the minimum current density in the casing is where the point current source is located. It is decided that the smaller the radius of the casing, the larger the amplitude of the current density is, the greater the amplitude of the current density. (5) when there is residual oil and no remaining oil in the well, the distribution of current density in the well is different. When there is no remaining oil, most of the axial current of the casing is concentrated in the upper part of the casing, that is, the upper part of the casing. When there is residual oil in the well, the axial current of the casing is denser on the upper end and both sides of the casing. When there is residual oil in the well, the current density mode of the point which is evenly selected between the casing is obviously smaller than that of the uniform selection point between the casing when there is no remaining oil between the wells. When the current density modulus is, if there is an oil layer between the casing, the current density mode value of the area will be obviously smaller than that of other points. (6) experimental study: the casing of one well is used as the source of the transmission line, the casing of the other well is used as the source of the receiving line, and many large outdoor tests have been carried out through continuous improvement and summary, and the line source is verified. The feasibility of the electromagnetic detection and receiving system of residual oil between wells is feasible. Finally, it is concluded that the wire should be exposed to the air and the wire should be shielded to reduce the external interference; the low pass filter should be added to obtain the larger induction signal.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325;TE327

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