Near real-time geomechanical modelling update and completion optimisation in the fold belt area of PNG: a case study with Oil Search Ltd

2010 ◽  
Vol 50 (2) ◽  
pp. 725 ◽  
Author(s):  
Katharine Burgdorff ◽  
David Castillo ◽  
Adrian White ◽  
Jon Rowse ◽  
Gavin Douglas ◽  
...  
Keyword(s):  
Real Time ◽  
Pore Pressure ◽  
Image Data ◽  
Wellbore Stability ◽  
Fold Belt ◽  
Geomechanical Model ◽  
High Resolution Image ◽  
Geomechanical Analysis ◽  
Stress Orientations

Collecting high-resolution image data in the majority of currently-drilled wells in the Papuan Fold Belt area has substantially improved our knowledge of the subsurface. A major contribution comes from the observation that the contemporary stress field and the pore pressure environment in the fold belt area are non-uniform. Comprehensive analysis of high-quality LWD images through the overburden has combated uncertainties brought about by the heterogeneity in the stresses and pore pressure. These data have been especially important when updating or constraining a geomechanical model in near real-time for the purpose of providing wellbore stability and completion recommendations. The geomechanical model unique to a particular part of the structure has been combined with finite-element modelling to help identify the optimal completion strategy for the reservoir sands in a number of wells. Recently, the near real-time geomechanical analysis has been used to quickly identify the optimal perforation direction in the reservoir in order to minimise the risk of solids production during completion.Essential data sources for the modelling include LWD images from the reservoir to confirm stress orientations and LWD density data and petrophysical analysis to accurately determine sand strength (UCS). A quick-look analysis uses the calculated UCS profile and the geomechanical model to identify, and therefore avoid perforating, any weak sections of the reservoir. Doing so hopefully mitigates the risk of solids production. This paper outlines the workflow and displays some results from the Papuan Fold Belt area.

scholarly journals Geomechanical Analysis for Deep Shale Gas Exploration Wells in the NDNR Blocks, Sichuan Basin, Southwest China

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1117 ◽  
Author(s):  
Majia Zheng ◽  
Hongming Tang ◽  
Hu Li ◽  
Jian Zheng ◽  
Cui Jing
Keyword(s):  
Pore Pressure ◽  
Shale Gas ◽  
Sichuan Basin ◽  
In Situ Stress ◽  
Wellbore Stability ◽  
Geomechanical Model ◽  
Stress Regime ◽  
Xujiahe Formation ◽  
Geomechanical Analysis

The abundant reserve of shale gas in Sichuan Basin has become a significant natural gas component in China. To achieve efficient development of shale gas, it is necessary to analyze the stress state, pore pressure, and reservoir mechanical properties such that an accurate geomechanical model can be established. In this paper, Six wells of Neijiang-Dazu and North Rongchang (NDNR) Block were thoroughly investigated to establish the geomechanical model for the study area. The well log analysis was performed to derive the in-situ stresses and pore pressure while the stress polygon was applied to constrain the value of the maximum horizontal principal stress. Image and caliper data, mini-frac test and laboratory rock mechanics test results were used to calibrate the geomechanical model. The model was further validated by comparing the model prediction against the actual wellbore failure observed in the field. It was found that it is associated with the strike-slip (SS) stress regime; the orientation of SHmax was inferred to be 106–130° N. The pore pressure appears to be approximately hydrostatic from the surface to 1000 m true vertical depth (TVD), but then becomes over-pressured from the Xujiahe formation. The geomechanical model can provide guidance for the subsequent drilling and completion in this area and be used to effectively avoid complex drilling events such as collapse, kick, and lost circulation (mud losses) along the entire well. Also, the in-situ stress and pore pressure database can be used to analyze wellbore stability issues as well as help design hydraulic fracturing operations.

Impact of High Resolution 3D Geomechanics on Well Optimization in the Southern Gulf of Suez, Egypt

2021 ◽  
Author(s):  
Mohamed Elkhawaga ◽  
Wael A. Elghaney ◽  
Rajarajan Naidu ◽  
Assef Hussen ◽  
Ramy Rafaat ◽  
...  
Keyword(s):  
High Resolution ◽  
Pore Pressure ◽  
Cost Optimization ◽  
Oil Field ◽  
Wellbore Stability ◽  
Gulf Of Suez ◽  
Geomechanical Model ◽  
3D Geomechanical Model ◽  
The Cost ◽  
The Impact

Abstract Optimizing the number of casing strings has a direct impact on cost of drilling a well. The objective of the case study presented in this paper is the demonstration of reducing cost through integration of data. This paper shows the impact of high-resolution 3D geomechanical modeling on well cost optimization for the GS327 Oil field. The field is located in the Sothern Gulf of Suez basin and has been developed by 20 wells The conventional casing design in the field included three sections. In this mature field, especially with the challenge of reducing production cost, it is imperative to look for opportunites to optimize cost in drilling new wells to sustain ptoduction. 3D geomechanics is crucial for such cases in order to optimize the cost per barrel at the same time help to drill new wells safely. An old wellbore stability study did not support the decision-maker to merge any hole sections. However, there was not geomechanics-related problems recorded during the drilling the drilling of different mud weights. In this study, a 3D geomechanical model was developed and the new mud weight calculations positively affected the casing design for two new wells. The cost optimization will be useful for any future wells to be drilled in this area. This study documents how a 3D geomechanical model helped in the successful delivery of objectives (guided by an understanding of pore pressure and rock properties) through revision of mud weight window calculations that helped in optimizing the casing design and eliminate the need for an intermediate casing. This study reveals that the new calculated pore pressure in the GS327 field is predominantly hydrostatic with a minor decline in the reservoir pressure. In addition, rock strength of the shale is moderately high and nearly homogeneous, which helped in achieving a new casing design for the last two drilled wells in the field.

A Geomechanical Model and Workflow for Calibrating Elastic Moduli and Min/Max Horizontal Stress from Well Logs in the Nahr Umr Shale

2021 ◽  
Author(s):  
Michael Alexander Shaver ◽  
Gilles Pierre Michel Segret ◽  
Denya Pratama Yudhia ◽  
Suhail Mohammed Al Ameri ◽  
Erwan Couziqou ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Drilling Fluid ◽  
Well Logging ◽  
Wellbore Stability ◽  
Rock Properties ◽  
Lateral Strain ◽  
Fluid Density ◽  
Geomechanical Model ◽  
Stability Problems ◽  
Stress Models

Abstract Thin layering and micro-fracturing of the thin laminated layers are some possible reasons for the wellbore stability problems of the Nahr Umr shale. If the drilling fluid density is too low, collapsing of the borehole is possible, and if the drilling fluid density is too high, invasion of the shale can occur, weakening the shale, making boreholes prone to instability. These effects can be semi-quantified and assessed through the development of a geomechanical model. The application of a geomechanical model of a reservoir and overlaying formations can be very useful for addressing ways to select a sweet spot and optimize the completion and development of a reservoir. The geomechanical model also provides a sound basis for addressing unforeseen drilling and borehole stability problems that are encountered during the life cycle of a reservoir. Key components of any geomechanical model are the principal stresses at depth: overburden, minimum horizontal principle stress, and maximum horizontal principle stress. These determine the existing tectonic fault regime: normal, strike-slip, and reverse. Additional components of a geomechanical model are pore pressure, unconfined compressive strength (UCS) rock strength, tilted anisotropy, and fracture and faults from image logs and seismic. Unfortunately, models used to make continuous well logging depth-based stress predictions involve some parameters that are derived from laboratory tests, fracture injection tests, and the actual fracturing of a well—all contributing to the uncertainty of the model predictions. This paper addresses ways to obtain these key parameter components of the geomechanical model from well logging data calibrated to ancillary data. It is shown how stress, UCS, and pore pressure prediction and interpretation can be improved by developing and applying models using wellbore acoustic, triple combo, and borehole image data calibrated to laboratory and field measurements. The nahr umr shale and other organic mudstone formations exhibit vertical transverse isotropic (VTI) anisotropy in the sense that rock properties are different in the vertical and horizontal directions (assuming non-tilted flatbed layering), the horizontal acoustic velocity is different from that of vertical velocity. This necessitates the building of anisotropic moduli and stress models. The anisotropic stress models require lateral strain, which as shown in the paper, can be obtained from micro-frac tests and/or borehole breakout data.

Updating the Geomechanical Model and Calibrating Pore Pressure From 3D Seismic Using Data from the Gnu-1 Well, Dampier Sub-basin, Australia

2009 ◽  
Vol 12 (03) ◽  
pp. 408-418 ◽  
Author(s):  
Adrian White ◽  
Brett McIntyre ◽  
David Castillo ◽  
Julie Trotta ◽  
Marian Magee ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Seismic Velocity ◽  
Image Data ◽  
Natural Fracture ◽  
Post Mortem ◽  
3D Seismic ◽  
Geomechanical Model ◽  
Gas Field ◽  
The North ◽  
Prime Concern

Summary A post-mortem analysis of the Gnu-1 well was conducted to help us to understand drilling experiences in the context of the pore-pressure and stress profiles. The post-mortem involved a review of the drilling experiences and an analysis of CAST image data, wireline-log data, and the logging-while-drilling (LWD) logs. This information was used to refine and verify a geomechanical model (in-situ stress, pore pressure, and rock-mechanical properties) in the vicinity of the Gnu-1 well. Of prime concern was the verification of the predrill pore-pressure prediction previously undertaken using 3D-seismic-velocity data and offset-well data. Wellbore-failure and natural-fracture analyses were integral parts of the post-mortem. Wellbore breakouts seen in the image data allowed the pore pressure in the 8.5-in. hole section of Well Gnu-1 to be constrained. Modeling using image data collected in the Athol formation indicates that the pore pressure does not increase as rapidly as was estimated in the predrill study. Pore pressures in the North Rankin formation and below were consistent with the predrill study. The geomechanical model was able to explain the losses seen in the Athol formation in Well Gnu-1 when using the mud weights experienced by the open hole at the time of drilling. Introduction The Gnu prospect is situated in the northern portion of Block WA-209-P in the Dampier subbasin, Australian northwest shelf (Fig. 1). The prospect is located within the Reindeer gas field. A number of offset wells exist in the region, the closest wells being Well Reindeer-1 (approximately 1.5 km to the northeast) and Well Caribou-1 (2 km to the southeast). Well Gnu-1 was designed as an exploration well. The anticipated overburden stratigraphy at the location of Well Gnu-1 consists of Tertiary and Upper Cretaceous carbonates, marls and siltstones that overlie Cretaceous claystones, siltstones and minor sandstones, and greensands. The primary aim was to drill vertically to intersect the Muderongia australis glauconitic sandstone and then to build angle and continue drilling a deviated hole through the main Reindeer field gas appraisal within the Legendre formation and into the North Rankin, Brigadier, and Mungaroo formations.

Integrated pre-drill and real-time geomechanical modelling brings significant benefits to deepwater wildcat exploration drilling campaign – a case study

2017 ◽  
Vol 57 (2) ◽  
pp. 698
Author(s):  
M. Sadegh Asadi ◽  
Amitava Ghosh ◽  
Sanjeev Bordoloi ◽  
Michael Reese
Keyword(s):  
Real Time ◽  
Wellbore Stability ◽  
Model Parameters ◽  
Seismic Velocities ◽  
Real Time Monitoring ◽  
Case Scenario ◽  
Worst Case ◽  
Primary Input ◽  
Exploratory Wells

This case study demonstrates the significance of integrated pre-drill geomechanical modelling and real-time monitoring for drilling wildcat exploratory wells in the deepwater settings of an offshore field in South-East Asia. The key challenges in the area include deeper water depths (1.6 km), lack of relevant offset well information and a complex geological setting. In this project, the primary input data for the pre-drill geomechanical model were low resolution 2D seismic velocities derived from an un-calibrated velocity model and petrophysical data from an offset well located in shallow waters, 100 km away from the deepwater prospect. During pre-drill planning, a contingency casing plan was put in place to consider the uncertainties in the model and cover the worst-case scenario of high pore pressure (PP). To reduce the uncertainty during drilling, the well was monitored in real-time and the pre-drill predictions improved whenever new information or data became available. The objective was to have good data coverage to assist in real-time geomechanical modelling for operational decision making. Real-time wellbore stability monitoring was carried out by utilising all available drilling and logging data as well as logging while drilling (LWD), pressure measurements and seismic while drilling (SWD) velocities. Wellsite interpretation on cuttings, cavings and formation gases were also integrated into the model predictions. Based on real-time monitoring, pre-drill predictions and model parameters were continuously updated for the next planned section at the end of each section target depth (TD). Interactive real-time monitoring with continuous pre-drill model updates before drilling the subsequent sections helped to not only deepen the intermediate hole sections, but also to drill efficiently with proper mud weight management and without any significant wellbore instability issues. This integrated workflow helped to successfully drill two exploratory wells, with the major benefit of eliminating the contingency 6ʹʹ slim-hole section.

Effective Real-Time Pore Pressure Monitoring Using Well Events: Case Study of Deepwater West Africa - Nigeria

2017 ◽  
Author(s):  
J. A. Onyeji ◽  
A. A. Adebayo ◽  
T. W. Stafford ◽  
O. A. Ekun ◽  
H. Onu ◽  
...  
Keyword(s):  
West Africa ◽  
Real Time ◽  
Pore Pressure ◽  
Pressure Monitoring

Analysis of Wellbore Instability in an Offshore Field: A Case Study

2018 ◽  
Author(s):  
Nubia Aurora González Molano ◽  
José Alvarellos Iglesias ◽  
Pablo Enrique Vargas Mendoza ◽  
M. R. Lakshmikantha
Keyword(s):  
Field Effect ◽  
Point Of View ◽  
Wellbore Stability ◽  
Geomechanical Model ◽  
Wellbore Instability ◽  
3D Geomechanical Model ◽  
Shale Formation ◽  
Major Factors ◽  
Offshore Field

Several wellbore instability problems have been encountered during drilling a shale formation in an offshore field, leading to the collapse of the main borehole and resulting in several sidetracks. In this study, an integrated 1D & 3D Geomechanical model was built for the field in order to investigate the major factors that control the instability problems from a Geomechanical point of view and to design an optimum mud window for planned wells in the field. Effect of bedding on wellbore stability was the most important factor to explain the observed drilling events. Optimized well paths for planned wells were proposed based on results of a sensitivity analysis of the effect of bedding orientation on wellbore stability. It has been observed that bedding exposed depends not only on well inclination but also on dip of the formation, attack angle, and azimuth.

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