A log based analysis to estimate mechanical properties and in-situ stresses in a shale gas well in North Perth Basin

نویسندگان

  • S. Archer
  • V. Rasouli
چکیده

In drilling operation the design of a proper mud weight to avoid any instability’s is important. A low mud weight may cause breakouts around the borehole whereas a high mud weight can fracture the formation. Mud weight design is based on two main factors: the mechanical properties of formations being drilled and the state of in-situ stresses in the field. While drilling in soft formations are thought to be more prone to drilling related issues than hard formations, there are several cases where opposite observations have been reported. This is indeed due to a high stress anisotropy which can apply a large shear stress to the rock to fail it. As it is seen, in order to define the stable mud weight windows for drilling it is important to not only have a good understanding about the mechanical properties of formations but also a good estimation of the state of stresses in the field. In this study we used a log based methodology to extract rock elastic and strength properties as well as the magnitude of stresses including vertical and maximum and minimum horizontal stresses. This is based on the fundamental relationship between physical properties of rocks as captured in petrophysical logs (such as sound velocity or density) and mechanical properties, such as uniaxial compressive strength. Due to rapid increase in developing unconventional reservoirs, in particular in Australia, in this study we applied the log based analysis as a case study to a shale gas well drilled in the North Perth Basin. Continuous logs of elastic and strength properties were extracted using available correlations and were calibrated at some depths where the triaxial lab tests results were reported on some core samples. The pore pressure and stress profiles were estimated using poro-elastic relationships. Pore pressure profile was calibrated using MDT data, the minimum stress profile was calibrated against the leak-off test data and maximum stress curve was fixed in a way to Petroleum and Mineral Resources 163 www.witpress.com, ISSN 1743-3533 (on-line) WIT Transactions on Engineering Sciences, Vol 81, © 201 WIT Press 2 doi:10.2495/PMR120151 recover the failures observed by callipers. The estimated logs, also called rock mechanical model (RMM) or mechanical earth model (MEM) was used to determine the stable mud weight windows for drilling. The RMM is the input for many other studies including, hydraulic fracturing initiation pressure and sanding analysis.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Evaluation of Reservoir Properties Using Wireline Logs of Well Sarai-Sidhu-1, Punjab Platform, Central Indus Basin, Pakistan

The well Sarai Sidhu-01 is located on Punjab Platform, Central Indus Basin, Pakistan. Punjab Platform is the eastern part of Central Indus Basin, and tectonically it is the stable portion of Indus Basin, which was least affected during Tertiary Himalayan orogeny. This study attempts to decipher reservoir potential for hydrocarbon exploration. It aims to delineate a subsurface hydrocarbon bearin...

متن کامل

Application of Well Log Analysis to Assess the Petrophysical Parameters of the Early Eocene Sui Main Limestone (SML) in Kharnhak-1 Well, Middle Indus Basin, Pakistan

The petrophysical analysis of the early Eocene Sui Main Limestone (SML) has been conducted in Kharnhak-1 well for the prospect of the hydrocarbon exploration of the Khairpur-Jacobabad High, Middle Indus Basin, Pakistan. The petrophysical analysis of SML is carried out on the basis of well logs including gamma ray, spontaneous potential, resistivity, neutron, and density logs. These analyses lea...

متن کامل

In-situ stress regime in the Asmari reservoir of the Zeloi and Lali oil fields, northwest of the Dezful embayment in Zagros fold-thrust belt, Iran

This paper analyzes in-situ stress field in the Asmari formation with in the complex structures of the Zeloi and Lali oilfields located in the Dezful embayment, SW Iran. The orientation of the maximum horizontal stress, SHmax is determined on the basis of compressive borehole breakouts and drilling-induced tensile fractures observed in eight oil wells, in which we focus on well-log based method...

متن کامل

Development of a mechanical earth model in an Iranian off-shore gas field

Wellbore instability is a quite common event during drilling, and causes many problems such as stuck pipe and lost circulation. It is primarily due to the inadequate understanding of the rock properties, pore pressure, and earth stress environment prior to well construction. This study aims to use the existing relevant logs, drilling, and other data from offset wells to construct a precise mech...

متن کامل

Paleoenvironmental Reconstruction of Miocene Surma Succession in the Well Rashidpur # 04 of Bengal Basin Using Log Facies Interpretation

Detailed log facies studies of Miocene succession in the well Rashidpur-04, Rashidpur structure, Surma Basin were carried out by integrating wireline log and limited core sample data in order to reconstruct the paleoenvironments of deposition. Based on the analysis of the log motifs, grain size, sand/shale ratio and major change in gamma ray log motifs, two major depositional sequences were ide...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2012