Construction of a Mechanical Earth Model to Determine a Safe Mud Window In one of the southwestern Oilfields of Iran

Document Type : Research Paper

Authors

1 Department of Mining Engineering, Faculty of Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Department of Chemical and Petroleum Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

10.22078/pr.2024.5548.3462

Abstract

In contemporary oil and gas industry projects, there is a notable prevalence of technical and economic obstacles. As a result, mitigating non-productive time (NPT) is imperative in preventing loss, kicks, and instability. The precision of pore pressure and fracture pressure forecasts is pivotal in ascertaining the normal compaction trend. This research has introduced a mud window model based on the geomechanical attributes of a prominent oilfield located in the southwestern region of Iran. The Earth model was formulated utilizing Geolog v.19 software. The initial phase encompassed the determination of the Normal Compaction Trend, followed by a comparative evaluation and the selection of the optimal function. Pore pressure values were established using the Eaton method, which was correlated with data collected from the oilfield and its vicinity. Establishing the optimal correlation among sonic velocity, density, and resistivity logs is essential to initiate the mud window. The fracture pressure prediction was carried out using the Breckels_van_Eeklen and Hubbert-Willis method, which closely aligned with the drilling report. A comparison of in-situ stress between the oilfield and the well indicated that despite the prevalent slip-strike fault stress map, the stress regime of this well was normal. The in-situ stress was determined by overlaying the stress polygon obtained from the sonic log with the one derived from the Mogi-Coulomb analysis. Analysis of the optimal mud window using various failure criteria indicated that the Mogi-Coulomb criterion takes precedence over other failure criteria. The optimal mud window ranges from 17 to 18.2 at a depth between 4002 and 4309. The Mohr-Coulomb failure criteria resulted in underestimating the optimal mud window compared to other criteria.

Keywords

Main Subjects