Geomechanical study of gas reservoir rock using vertical seismic profile and petrophysical data (continental shelf in southern Iran)

ABSTRACT

Geomechanics is a science dealing with the study of the behaviour of rocks affected by stress. It has various applications in utilisation from oil and gas reservoirs including of the wellbore stability analysis and determination of safe mud window. The main aim of this paper is geomechanical study of Kangan–Dalan reservoir in South Pars gas field in Persian Gulf in south Iran. Seismic waves are affected by physical properties of rocks when passing underground formations; thus, the velocity of these waves is a desired parameter for estimation of geomechanical properties. The velocity of compressional and shear waves has been determined with processing seismic data resulting from vertical seismic profile. In this paper, after calculation of elastic modules of reservoir rock, the imposed stress field was determined and these concepts were used for engineering calculations such as safe mud window, wellbore stability analysis and sand production potential. For well drilling in Kangan-Dalan reservoir, the minimum and maximum mud weights were proposed in average as 1.093 and 2.011 gr/cc and average critical mud weight as 2.48 gr/cc such that if the weight of mud increases, the tensile fractures will be created on the formation and complete loss of mud will happen.

KEYWORDS:

• Geomechanics
• gas reservoir
• petrophysics
• VSP
• elastic modules
• wellbore stability

Acknowledgment

Authors thank National Iranian Oil Company (NIOC) for their help and financial support.

Disclosure statement

No potential conflict of interest was reported by the authors.