This paper discusses the results of an innovative methodology using Dionisos 4D forward stratigraphic modelling of Middle Eastern carbonate reservoirs on a field scale. Traditional stochastic techniques do not sufficiently capture carbonate reservoir heterogeneities, reducing the accuracy of static and dynamic models. The methodology applied to three Lower Cretaceous UAE reservoirs, uses a deterministic approach that aims to define carbonate heterogeneity and provides a structure to develop a more accurate and usable static and dynamic model for field development. Dionisos uses a predefined sequence stratigraphic scheme as a framework. A reference case model is manually calibrated to environmental parameters, followed by automated multi-realisations that generate several other plausible calibrated models. A sensitivity analysis provides an indication of the influencing environmental parameters controlling facies and texture distribution.The calibrated forward stratigraphic models resulted in the generation of 14 carbonate textures for the three reservoirs using a 200x200 m grid size and a 50 kyrs time step. Carbonate lithology production (mud, fine, coarse, bioconstructions) varies between 0 and 350 m/Ma, wave direction is SW (200 -260°); wave action depth 7-18 m while wave energies vary between 0 and 140 kW/m. Sediment diffusion coefficients by wave transport range from 0.1 (mud) to 0.0008 km 2 /kyr (bioconstructions) while gravity driven transports from 0.1 to 0.001 km 2 /kyr. The lower part of Reservoir A is characterised by low angle TST sequences dominated by algal boundstones-floatstones. Deposition continued with the development of a low relief margin with aggradational to progradational architectures comprising rudist shoals. This defined a topographic split into platform, slope and basin with lateral texture heterogeneities showing a northward deepening trend. The successive clinoform top sets (Seq4a, b) are rich in rudist boundstones-floatstones with lower slope dominated by packstones-wackestones.Reservoir B and C are isopach with strong lateral variability in carbonate texture as evidenced by well data. The overall architecture of the sedimentary systems consists of low relief interconnected algal boundstone-floatstone mounds separated by gentle depressions dominated by fine grained sedimentation. The numerical simulation of these systems was driven by a carbonate production law as a function of the substratum energy and bathymetry under dynamic subsidence/uplift conditions. The innovative workflow applied at field scale allowed the modelling of complex carbonate geometries and associated textures honouring lateral and vertical heterogeneities observed at wells. The application of this workflow as alternative/complement to stochastic methodologies brings further insights on the proposed sequence stratigraphic framework allowing the confidence and predictability of static and dynamic facies models to be increased.

Uncertainty analysis using experimental design and response surface techniques has been extensively used in the field of reservoir simulation. This study outlines an innovative workflow to generate multiple realizations of forward stratigraphic modelling of three Lower Cretaceous reservoirs from onshore Abu Dhabi. Forward stratigraphic modelling is a deterministic technique that simulates basin infill providing a better understanding of vertical and lateral facies distribution and connectivity in sedimentary basins. During the course of forward modelling a variety of environmental and stratigraphic parameters are used. Due to the uncertainties of these parameters it is critical to assess their impact on the development of the basin fill. The experimental design and response surface techniques have been innovatively applied at reservoir scale to enhance the understanding of major controlling parameters on carbonate production and to produce alternative facies distribution scenarios in the study reservoirs. The methodology used in this study was based on running multiple simulations, through varying key input parameters. The best stratigraphic models were then selected based on calibration quality and geological consistency. Calibration quality was assessed by two user defined quantitative functions called Thickness Calibration Indicator and Rock Texture Calibration Indicator. The initial step in the workflow identified uncertain environmental parameters (e.g. eustasy, carbonate production versus depth, carbonate production versus time, wave parameters, gravity and wave transport and erosion rates) from a manually calibrated reference case and ranges of values for each parameter defined based on the knowledge of geology over the area. Latin Hypercube experimental design was then used to define a set of simulations to allow an efficient and uniform sampling of the entire uncertain domain. Sensitivity analysis was then performed on simulation responses (texture and thickness calibration indicators) using the technique of nonparametric Response Surface Modelling (RSM). The influence (quantitative and qualitative) of the impacting parameters on responses was studied to identify the most influential parameters as well as the ranges yielding good calibration indicator values. A further set of simulations was then launched that considered the most influential parameters and their precise ranges. Non critical parameters were assigned with the constant values from the reference case model. These simulations generated a series of well calibrated models. A filtering of simulations with high calibration indicator values and good geological consistency was then performed to choose acceptable multi-realizations. Finally, thickness and texture confidence properties were mapped based on the selected multi-realizations and the reference case. Sensitivity study on three Lower Cretaceous reservoirs from onshore Abu Dhabi successfully addressed the uncertainty associated with forward stratigraphic model input parameters. Sensitivity analysis was performed using Experimental Design and RSM. This was applied to enhance the understanding of the major controlling environmental parameters on carbonate production for individual sequence with each of the study reservoirs.

In the quest of increasing production capacity to meet future demands E&P companies have embarked in the journey of re-developing their matured assets. This is enabled using several field development programmes that include in-fill drilling, horizontal drilling, underbalanced drilling and drilling unconventional reservoirs. These programmes require high quality offset well data along with real time data for better planning and execution to successfully manage drilling risk, reduce non-productive time and cost to achieve the field development objective.Historically a huge volume of operational data has been acquired from the large number of wells drilled. Data include well trajectories, casing points, casing analysis, drilling risks, drilling events, BHA performance, operational window, cost, time etc. Maintaining the historical offset drilling data systematically in a well organized manner is vital to unlock its business value and enable better drilling data analysis along with real time data. Technology aided programs such as collaborative well planning, geo steering, real time operations center, require offset well data integrated into real time data for integrated and optimized workflows during planning and execution. This includes building better engineering models and earth models. This paper discuss present data challenges and the approach towards building an Drilling Integrated Workflow Environment (DIWE) comprising of high quality drilling knowledge base, real time data enabled by data standards and the framework to support next generation well planning and drilling workflows.DIWE enables improved planning and execution by supporting integrated workflows that aim to mitigate drilling hazards, improve operational awareness, optimize well design, cost effective construction, and better well placement moving towards achieving drilling excellence

Borehole geology has a long history of interpreting natural fractures from image logs. During image log interpretation it is common that drilling induced fractures of a variety of shapes are observed which can lead to confusion and misinterpretation. This presentation discusses conditions at which induced fractures can develop and emphasises the need for an integrated approach for interpreting image logs to distinguish natural and induced fractures. Well based geomechanical simulations and verification of induced fracture development are also covered. The key to understanding a borehole image log is the ability to distinguish between natural reservoir and drilling induced fractures. The addition of optimal drilling conditions (hole stability, mud parameters etc.) will allow good quality data capture and enhance accuracy of interpretation. An induced fracture (drilling induced tensile fracture, Figure 1) is the result of the redistribution of hoop stresses around the borehole during the drilling process. The shape and orientation of an induced fracture is dependent upon a number of factors, including: hoop stress distribution around the borehole, bore hole deviation/azimuth, w.r.t present day stress orientation, pressure overbalance, borehole cooling effect and drilling parameters (e.g. weight on bit, torque). To add to the complexity of borehole image interpretation, development of drilling induced fractures can be influenced by pre-existing natural fractures leading to the development of complex features in the image log.

E&P Operators are facing challenges with the on-going development of brown fields and the increasing need for accurate wellbore placement and geosteering during infill drilling. This is driven by business plans that involve large in fill well drilling program. The planning and execution of these in fill wells will involve the drilling of highly deviated, horizontal and extended reach wells. Good use has been made historically of the geosteering services provided by contractors in order to support drilling programs. This paper investigate the process of establishing an Integrated Geosteering Environment (IGE) that would enable efficient collaboration between reservoir geologist, petrophysicist, operational geologists, reservoir engineers and drillers engaged in field development. This environment makes use of a real time data to enable the drilling team to reduce risk and reservoir uncertainty while maximizing wellbore contact with the zone of interest. This will translate into reduced drilling time, better well placement and an increase in capital efficiency. The paper primarily focuses on the establishment of the IGE that will enable the development of workflows to optimize the placement of horizontal wellbore to achieve the business objective. The workflows cover predrill planning, drilling execution including 24/7 real time monitoring to steer the well, post well evaluation and update the reservoir model. This is enabled by real time data acquired while drilling along with modelling visualization tools. Transforming from the current working environment into an Integrated Geosteering Environment combined with a real time Drilling Environment enables effective decision making and increased business agility towards achieving Operator business objectives, increasing oil recovery and sustaining the production capacity of brownfields. There are several papers in the past addressing collaborative work environment or shared earth model. This paper discusses real time integrated workflow between sub-surface and drilling domains from a geosteering perspective.