气井产量递减分析

【作者】 梁彬；

【导师】 李闽；

【作者基本信息】 西南石油学院 ， 油气田开发工程， 2005， 硕士

【摘要】 Arps把油气井的产量递减归为指数、双曲和调和递减三种类型,并提出了确定递减参数和预测未来动态的图版拟合方法,但这种方法不能反求地层参数。Fetkovich和Fraim等人在Arps提出的产量递减规律的基础上,结合物质平衡方程和拟稳态油气井产能方程,建立了一套油气井产量递减的图版拟合方法,该方法可以反求地层参数。Fraim同时指出,对于定井底流压生产的气井,产量与标准化时间成指数递减关系,根据这一特点,李闽用回归分析建立了气井产量递减的自动拟合方法。 在前人研究的基础上,本文研究了正常压力气藏气井和异常高压气藏气井产量递减的自动拟合方法,并同数值模拟的结果进行了对比。研究内容包括:(1)研究正常压力气藏气井自动拟合方法的适用条件,即论证模型对不同储层物性和边界形状的适用条件;(2)研究运用自动拟合方法确定的地层参数和地质储量是否正确的检验标准;(3)研究用拟稳态生产数据及全部生产数据进行自动拟合对计算结果的影响;(4)建立考虑岩石和水压缩性的异常高压气藏气井的产量递减自动拟合的数学模型及计算结果是否正确的检验标准。 根据李闽产量递减模型和本文提出的产量递减模型编制了《气井携液及产量递减分析软件》中的“产量递减”模块,运用该模块可以计算气井产量递减参数、地层参数和地质储量。本文共进行了21井次的单井数值模拟、37井次的自动拟合计算以及1井次的现场实例分析,对比数值模拟计算结果和自动拟合计算结果,得出了以下认识与结论: (1)对于特低渗的正常压力气藏,运用李闽产量递减模型计算的递减参数和地质储量的偏差很大。边界形状对计算结果影响很小,总体而言,边界形状规则的气藏中心一口气井的计算结果优于其它情况。 (2)标准化压力与标准化时间半对数图为直线以及预测产量能拟合实际产量是检验计算的地层参数和地质储量正确与否的标准。若预测产量能拟合实际产量,而半对数直线后端向上弯曲,则说明计算的地质储量偏大。 (3)去掉不稳定生产数据的计算结果比用全部生产数据的计算结果更接近实际情况。 (4)可以用本文提出的考虑岩石和水压缩性的异常高压气藏气井产量递减自动拟合模型分析异常高压气藏气井的产量递减。标准化压力与标准化时间半对数图为直线以及预测产量能拟合实际产量仍是检验计算结果是否正确的标准,而且去掉不稳定生产数据的计算结果比用全部生产数据的计算结果更准确。 通过本文的研究,给出了李闽自动拟合方法的适用条件及计算结果正确于否的检验标准,同时提出了异常高压气藏气井的产量递减自动拟合模型。更多还原

【Abstract】 Arps categorized the rate decline of oil and gas well as exponential、 hyperbolic and harmonic, and brought forward a technique of type-curve matching, which can determine the decline parameters and predict the further performances but cannot obtain the formation parameters. Basing on Arps rate decline law and combining the material balance equation with the pseudo steady-state deliverability equation, Fetkovich and Fraim et al established a suit of type-curve matching of gas-well (oil-well)rate decline, which can determine the formation parameters. At the same time, Fraim pointed out that, the rate is exponentially related to the normalized time for a gas well producing against constant bottom hole flowing pressure. On the foundation of this characteristic, limin set up a set of technique for automatically matching the gas-well rate decline with regression analysis.Founded on the research fruits of previous researchers, this dissertation is mainly concerned with the technique for automatically matching the gas-well rate decline of both normally pressured and abnormally pressured gas reservoir, and compares the calculated results with those of numerical simulation. The research content is following:(1)investigate the application confinement of the technique for automatically matching the rate decline of the normally pressured gas reservoir, that is, demonstrate the application confinement of this technique for various reservoir properties and different boundary shapes;(2)study the touchstone that justifies the formation parameters and the OGIP calculated through the technique of automatic matching;(3) research the effect of both pseudo-steady and whole production data on the calculated values; (4)establish the mathematical model for automatically matching the rate decline of abnormally pressured gas reservoir, for which the compressibility of both water and rock is beyond neglect; and that, determine the touchstone that confirms the calculated values.Grounding on limin’s decline model and the new decline model presented in this paper, the module "rate decline" in the software "Analysis of gas-well load up and rate decline" is programmed.Through this module, the rate decline parameters、 formation parameters and OGIP can be determined. This thesis has performed altogether 21 single-well numerical simulations 、 37 automatic matching calculations and 1 field case analysis ; Comparing the results of numerical simulation with those of automatic matching presented in this paper, we acquire following conclusions:(1)For normally pressured gas reservoirs with extra low permeability, the decline parameters and OGIP calculated through limin’s rate decline model greatly deviate their actual values.The boundary shape has little effect on the calculated results, to sum up, the calculated results forregular boundary shape with the well in center are better than other cases.(2)The normalized pressure is linearly related to the normalized time on the semi log curve, and also, the predicted gas rate can well match the actual gas rate, which is the touchstone for justifying the calculated formation parameters and OGIP. If the predicted gas rate can match the actual gas rate, whereas the back end of the semi log beeline bends upwards, this shows that the calculated OGIP is slightly larger.(3)The calculated results without consideration of unsteady production data are closer to actual case than those with consideration of all the production data.(4)For abnormally pressured gas reservoir, the model for automatically matching the rate decline, which takes the compressibility of both rock and water into account, can be used to analyze its rate decline. In addition, linear relationship between the normalized pressure and normalized time on the semi log curve, together with the good matching of actual gas rate with the predicted gas rate, is also the touchstone for justifying the calculated results, and the calculated results without consideration of unsteady production data are closer to actual case than those with consideration of all the production data.Through above investigation in this paper, the application confinement for limin’s automatic matching technique and the touchstone for justifying the calculated results are presented; moreover, the thesis also advances a model for automatically matching the rate decline of the abnormally pressured gas reservoir.更多还原