Abstract

Porosity is a key parameter for reservoir evaluation. Inferring the porosity from seismic data is often challenging and prone to uncertainties due to number of factors. The main aim of this paper is to show the applicability of seismic inversion on old vintage seismic data to map spatial porosity at reservoir level. 3D-seismic and wireline log data are used to map the reservoir properties of the Lower Goru productive sands in the Gambat Latif block, Central Indus Basin, Pakistan. The Lower Goru formation was interpreted with the help of seismic and well data. Interpreted horizons are thus further used in model-based seismic inversion techniques to map the spatial distribution of porosity. Well-log data are used in the construction of low acoustic impedance models. Calibration of reservoir porosity with inverted acoustic impedance is achieved through well-log data. The results from model-based inversion reasonably estimate the porosity distribution within the C-sand interval of the Lower Goru Member. After post-stack inversion, the porosity values at wells Tajjal-01, Tajjal-02 and Tajjal-03 are 10%, 8% and 12%, respectively. Porosity values calculated from post-stack inversion at the corresponding well locations are in good agreement with the borehole-derived porosity.

Research highlights

1. 1.

   Cross-plots of acoustic impedance and effective porosity can differentiate between tight porous and mixed sand facies.

2. 2.

   Model-based seismic inversion can delineate tight sands.

3. 3.

   The spatial distribution of porosity can be reasonably estimated with the help of inverse linear relationships between impedance and porosity.

中文翻译：

---

基于模型的叠后反演在含孔隙，致密和混合相储层砂岩表征中的应用：以巴基斯坦中部印度河流域为例

摘要

孔隙度是评价储层的关键参数。从地震数据推断孔隙度通常具有挑战性，并且由于多种因素而容易产生不确定性。本文的主要目的是说明地震反演在旧的老式地震数据上的适用性，以绘制储层水平的空间孔隙度。3D地震和电缆测井数据用于绘制巴基斯坦中部印度河流域Gambat Latif区块下Goru产砂的储层特性。下Goru地层在地震和井数据的帮助下进行了解释。因此，在基于模型的地震反演技术中还可以使用已解释的层位，以绘制孔隙度的空间分布图。测井数据用于构建低声阻抗模型。通过测井数据可以实现具有反声阻抗的储层孔隙度标定。基于模型的反演结果合理地估计了下Goru成员C砂岩区间内的孔隙度分布。叠后反演后，Tajjal-01井，Tajjal-02井和Tajjal-03井的孔隙率分别为10％，8％和12％。根据相应井位置的叠后反演计算出的孔隙度值与源自钻孔的孔隙度非常吻合。

研究重点

1. 1。

   声阻抗和有效孔隙度的交叉图可以区分致密的孔隙相和混合的砂相。

2. 2。

   基于模型的地震反演可以勾勒出致密的砂岩。

3. 3。

   孔隙度的空间分布可以借助阻抗和孔隙度之间的反线性关系来合理估计。