Advances in Earth Science ›› 2018, Vol. 33 ›› Issue (4): 416-424.

### Optimization of the Rock Physical Model in Tight Sandstone Reservoir

Lingyun Jia 1( ), Lin Li 1, Qianyao Wang 2, Jinfeng Ma 1, Daxing Wang 3

1. 1.National & Local Joint Engineering Research Center of Carbon Capture and Storage Technology, Department of Geology of Northwest University, Xi’an 710069, China;
2.China Coal Technology Engineering Group Xi’an Research Institute, Xi’an 710077, China;
3.Research Institute of Exploration and Development, Changqing Oil Field Company, PetroChina, Xi’an 710018,China;
• Received:2017-09-08 Revised:2018-01-25 Online:2018-04-20 Published:2018-05-24
• About author:

First author:Jia Lingyun(1983-),female,Datong City,Shanxi Province,Ph. D student. Research areas include seismic data interpretation, inversion and others.E-mail:1027314266@qq.com

• Supported by:
Project supported by the National High Technology Research and Development Program of China “Key technique for CO 2 sequestration” (No.2012AA050103).

Lingyun Jia, Lin Li, Qianyao Wang, Jinfeng Ma, Daxing Wang. Optimization of the Rock Physical Model in Tight Sandstone Reservoir[J]. Advances in Earth Science, 2018, 33(4): 416-424.

Krief model, Nur model and Pride-Lee model are usually used to calculate dry rock modulus of sandstone reservoirs, but they are not effective for tight sandstone reservoirs. Based on Krief model and Nur model, and minimizing the difference between predicted P-wave or S-wave velocities and measured velocities, we acquireed lithologic index m in Krief model and critical porosity ?c in Nur model by Gassmann relationship. The empirical parameters used in the models are expressed as the values changing with depth, so the accuracy of Krief and Nur models to estimate the P-wave and S-wave velocities was improved, and these two models are called as the variable parameter Krief model and the variable parameter Nur model. In addition, comparing with prediction accuracy of P-wave and S-wave velocities under different constraints, we can see that the shear modulus formulas in the three models are more accurate and more suitable in the tight sandstone reservoir. Han’s relationship about Kdry and udry is not affected by porosity, lithology and other factors, and the paper established dry rock model by Han’s relationship and any one of the above three models. The new dry rock model was applied in the Gassmann relationship to predict S-wave velocity of H8 tight sandstone reservoir in Sulige Gas Filed, Ordos Basin, which improved the accuracy of predicting S-wave velocity. At the same time, lithology index m in Krief model, critical porosity ?c in Nur model and consolidation parameters c in Pride-Lee model which are corresponding to each sample can be obtained. The values of these parameters can reflect lithology difference, pore structure, compaction degree and other characteristics, which indicate the geological characteristics of the reservoir.

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