Application of Tracer Model in the Remaining Oil Distribution of 95 Block Oilfie

【前言】Application of Tracer Model in the Remaining Oil Distribution of 95 Block Oilfie由文秘帮小编整理而成，但愿对你的学习工作带来帮助。（2） Determine the size of the flooded layer thickness and permeability； （3） Verification of the fault and closed； （4） Determine the spacer layer is perforated and nature； （5） Effectiveness analysis of the development of adjustment measur...

Abstract. With the development and utilization of oil and gas fields， oil mining become more and more difficult. The remaining reserves of oil in the oil distribution is difficult to confirm， in order to understand and grasp the distribution of the remaining oil in the reservoir， calculated using tracer concentration methods used mathematical models to calculate the residual oil saturation in the reservoir， from the theoretical analysis of tracer migration process， you can more accurately determine the distribution of the remaining oil， this method has good prospects for development.

Keywords： Tracer； Mathematical Model； Tracer Production Curve； Residual Oil Saturation

1. Introduction

Have decades of history tracing technique， its usefulness is that it can display its liquid dissolved in the presence of porous media flow direction， flow rate. Common oilfield has five tracers， including： a radioisotope， a non-radioactive isotope， easily detectable anion （NO3 -， Br -， I -）， a lower alcohol ester， and soluble chemical tracer. This article is easily detected using anion （NO3 -）. Well scene between tracer methods can be applied：

（1） Evaluation of reservoir heterogeneity；

（2） Determine the size of the flooded layer thickness and permeability；

（3） Verification of the fault and closed；

（4） Determine the spacer layer is perforated and nature；

（5） Effectiveness analysis of the development of adjustment measures [1].

2. The mechanism by flowing a tracer

In the component model， the components of the change is related to multiphase flow system， a variety of ways to coexist mass transfer， and is affected by many factors. Usually in porous media， tracer migration is determined by two factors： the convection and hydrodynamic dispersion.

Tracer migration law to meet the convection - diffusion equation， now for convection - diffusion equation simplifies solution， are the following：

（1） A one-dimensional homogeneous radial and equal thickness， without considering the inter-layer water channeling and oil wells degree of analytical solutions network a rule， the country and abroad are widely used in various fields of analysis；

（2） Consider only single-phase water flooded layer flow of an ideal tracer transport equation， the two-dimensional form， and specifically black oil model analysis solution available technology；

（3） The flow tube and chromatography to determine the combination of theory formation saturation analytical method [2].

3. The related problems of two-phase three-dimensional mathematical model of four-component

Wherein said component with i， j represents the phase， we have the problem of the mathematical model of the multi-component：

（1）

When the tracer injected into the reservoir， considering the tracer and reservoir water mass transfer factors completely miscible occur. So as to improve the formula：

（2）

For the problem of two-phase four components：

Component 1： Non-allocation of tracers， only soluble in the aqueous phase；

（3）

Component 2： distribution of tracers can exist in oil， water into two phases；

（4）

Three components： the water component， only present in the aqueous phase；

（5）

Component 4： oil component can be present only in the oil phase.

（6）

The multi-component model and chromatographic theory of knowledge， can build a three-dimensional two-phase four-component （oil， water， distribution of the tracer， non-distribution of tracer） mathematical model is derived by simplifying and ultimately can get out of the remaining oil saturation equation：

（7）

The model takes into account all the characteristics of the reservoir， diffuse， and that tracer retention， fluid gravity， capillary force and the oil flow ratio， take the numerical method to solve the delivery of the tracer to make the overall analysis， to determine significant value information， this study can be applied with water oil field tracer detection in the planning， design and analysis.

4. Analysis

To master the analytical methods between porosity solute transports is not difficult， however， due to the complexity of the equations， in order to effectively analyze solute transport， the rate constant region， radiation flow problem， then its methods is limited. In the range of steady state flow analysis method for the majority of the solution over time， solute transport is valid.

Usually describes the flow equations of solute in solution as follows：

Since the actual state taking into account the balance of the ion exchange action， it can have the formula：

（9）

No change with time for solving equations， boundary conditions appropriate original is required， including： Piccadilly Cray boundary conditions （such predetermined concentration of the solution of the boundary condition is part of the boundary）； Neumann boundary conditions （described in the Usually the concentration of a certain class of conditions after the boundary portion）； Alexis boundary conditions （the concentration of the solute and gradient described conditions）， which borders the expression as follows：

5. Case study

Guardian 95 blocks in oilfield tracer tests to analyze the strength of the remaining oil saturation techniques used in the field

The amount of tracer formula：

（13）

According to the obtained amount set by the former regime of injection wells and production wells around （95 - 69 95 - 20 95 - 43） were fitted， reviewing tracer production curve can be drawn for each production wells tracers such as small layer thickness， permeability formation parameters （see Table 4-1）.

In tracer monitoring， as a result of tracer injected underground water propulsion， and high forward speed， so the tracer mainly from the high permeability thin outputs. Data from Table 4-1， you can describe the distribution of residual oil saturation， according to the data in the table last remaining oil saturation can be determined for each small layer.

According to NO 3 - and amino acid and Naphthylamine reacts principle red complex， the outputs are determined by spectrophotometric method， you can draw a curve tracer concentration versus time that tracer production curve.

Drawn from the data in Table 95-43 wells tracer production curve

.

Fig.1. Tracer production graph of 95-43 wells

As can be seen from Figure 5-1， the same curve and the actual curve obtained by numerical techniques， the size of the peak fit. By calculating the saturation equation obtained inject the remaining oil saturation low permeability layer after tracer.

Tracer injection well area overview：

Xiaermen oil fields H2 Ⅲ group began the second polymer injection in December 2006， Ⅱ 2 block located ① ⑦ No fault number and sandwiched area that a total of five polymer injection wells， wells 19. The preferred that the polymer injection wells block 4： T6-226， a new secretion 7， 6-304， J6-122 wells tracer testing， its distribution profile shown in Figure 5-2.

6. Conclusions

As the tracer reservoir heterogeneity has evaluated to determine the volumetric sweep efficiency well network， permeability fluid saturation effect size， so more and more oil fields and other areas of concern. In this paper， a mathematical model to calculate the concentration of the tracer method under the residual oil saturation calculation and distribution， and the mathematical model of optimization factors， by simplifying and derivation， eventually get out of the remaining oil saturation equation， the next step in the remaining oil has important guiding significance.

Information needed to calculate the remaining oil in the production process for the oil field data with production data and the original test， the results of field development in the late adjustment programs provide the basis for the technology in the Guardian 95 results on the application of the actual situation is more agreement， according to the curve tracer production time and concentration of chart analysis， the concentration of tracer production vary greatly， indicating heterogeneity between wells still does not reflect the dynamic characteristics of heterogeneous characteristics， there may be cracks and other special hypertonic channel .

In the long run， the tracer technology has broad prospects， should be widely applied.

References

[1] Doris study method for determining inter-well tracer diffusion coefficient [M]. Hydrocarbon recovery techniques .1997，4 （2）： 59-64

[2] Wang Zuoying. Isotope tracers in oilfield steam flooding inter-well tracer test application [M]. Isotope .2000，13 （1）： 18-21

[3] Doris. Measured tracer diffusion constants and data interpretation methods [M]. Petroleum Exploration and Development 1999 （6）： 87-92

[4] Huang Zhen Qin. Tracer techniques in oilfield development application [M]. Hydrocarbon recovery techniques .1996，3 （4）： 39-43

[5] Jiangrui Zhong between various tracers well analysis technique [J]. Petroleum Journal .1996，17 （3）： 85-91

[6] Cattle lotus Inter-well tracer test residual oil saturation distribution technology in the Guardian 95 applications [M] .7 （4） ：57-64

[7] Li Shuxia. Numerical simulation of inter-well tracer tests [J]. Petroleum University .1997，21 （3）： 34-39

[8] Yang Daoyong. Miscible flooding tracer gas monitoring technology [J]. Petroleum election University （Natural Science Edition） 1999，23 （3）： 37-40

[9] Mr Lau. Conditions under simulated reservoir gas tracer retention measured [J]. Foreign oilfield engineering .1999，10 （3）： 1-6