Fan-deltaic environment offers a particular challenge for geostatistical modelling. Over the past decades, geostatistical methods are widely accepted and applied to simulate sedimentary microfacies. In this study we have selected Sequential Indicator Simulation (SIS) to generate our model and perform sensitivity analysis. Luanping fan-deltaic outcrop has been selected as a case study. The outcrop is located in Hebei province, China. The main outcrop cut by road is an excellently exposed study area, whose length and height are 1300 meters and 230 meters respectively. The orientation is nearly east-west. It was deposited from upper Jurassic to lower Cretaceous. Based on outcrop studies, 16 types of microfacies have been classified and for simplicity, they have been finally combined into 6 types of microfacies in stochastic simulation.

The 2-D grid of 470 ×290 (ΔX=2.5m, ΔY=0.8m) has been designed to establish a single deterministic (prototype) model of Luanping fan-deltaic outcrop. The model honors all existing data and represents a realistic geological interpretation as closely as possibly. The input data of SIS are extracted from prototype model at different well spaces of 100,200,300,400 and 500 meters. As a result, microfacies simulations are constructed under different well spaces. Comparing these simulations with prototype model, prediction accuracy and uncertainty analysis are presented in this study.

The study shows geostatistical tools can well reproduce prototype model of Luanping fan-deltaic outcrop. The prediction accuracy is largely relied on variogram model and proportion of each microfacies. Moreover, SIS can also reflect the microfacies distribution law of fan-delta, especially fan-deltaic plain can be reproduced under less information. Finally the results are applied to NY oilfield, China successfully.

You can access this article if you purchase or spend a download.