The Influence of Tectonic Forces on the Coupling Ratio of Sand Z-600, Keutapang Formation, North Sumatra Basin
Imam Setiaji Ronoatmojo1*, Muhamad Burhannudinnur1, Grace Stephani Titaley2
1Faculty of Earth Technology and Energy, Trisakti University
Jl. Kyai Tapa No.1, Jakarta, Indonesia
2PT. Pertamina EP, Menara Standard Chartered No 164, Lt 16, Jl. Prof. DR. Satrio, Jakarta 12950, Indonesia
email address: aji.rono[at]trisakti.ac.id
Abstract
The tectonic mechanism is a mechanism that involves tectonic conditions in the area which affects the dynamics of poroelasticity. Elastic modulus in the porous medium will go through change along with fluid dynamics. The loading factor role in the tectonic mechanism is followed by the tectonic forces. The aim of this study is to learn the impact of a tectonic mechanism on the coupling ratio during production and water injection. The objective zone of this study is a part of the thrust fault regime, which is changed to be the strike-slip fault regime. The sand reservoir of Z-600 is in the transition condition so that the dominance of S_V and S_hmin has a strong influence on a coupling ratio change. The fluid dynamics occurring during this period are water injection and oil production. Observations were made on mechanical properties and pore pressure changes. The coupling ratio estimation starting from 1994 until 2017 refers to a historical production matching to demonstrate rock strength responses in the variation of existing tectonic regime positions. Mohr diagram analysis was done, based on the Coulomb failure criterion. It demonstrates that pore pressure change is not always equal to the change of stress difference or deviatoric stress change, due to the nature of irreversible porosity change during fluid dynamics. The horizontal stress might cause shear tensile failure, it initiates a sanding problem potential.
Keywords: tectonic mechanism, coupling ratio, rock strength, shear-tensile failure, sanding problem
Topic: Petroleum and Geothermal Engineering