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Addis & Yassir Ltd. (U.K.) is a Geomechanical Engineering and Production Technology Advisory Company, Combining Subsurface Experience and Technology Implementation to Assess CCS Storage Integrity, Increase Oil & Gas Production while Reducing Costs and HSE Risks
CO2 Carbon Subsurface Sequestration and Containment
Disposal and long-term storage of CO2 in subsurface traps and old reservoirs relies on the CO2 remaining trapped and not leaking to the surface or to other layers over time. The integrity of the subsurface 'container' is key to successful sequestration projects.
The stresses acting on the trap and across any faults and fractures in the containment zone are a key to the long term viability of the CO2 injection and storage.
It is important to know not only the current day stresses, but the mechanisms controlling the present-day and future stress evolution, over the duration of the storage, and to monitor any changes.
Pore Pressure and Fracture Gradient Analysis
Pore Pressure and Fracture Gradients are the basis for hydrocarbon seal integrity evaluation, well design and casing setting depths. Addis & Yassir use both industry standard analysis and customised (overpressure) techniques including novel hydrodynamic analysis to determine the pore pressure distribution.
Fracture Gradient analysis uses the full suite of industry techniques as well as proprietary methods for compressive and tectonics regions.
Mechanical Earth Models
These models are static geological sub-surface models which provide the basic input for most geomechanical analyses, including stress and strength and mechanical property profiles.
The starting point for most Geomechanical analyses include 1D (well-based) MEMs, with 3D MEM used for sector- or Field-wide analyses
These analyses are provided with uncertainty assessments to support improved analyses and decision making.
(IPCC, 2005)
Wellbore Instability, Stuck Pipe and Drilling Problems
Borehole Instability is a common cause of stuck pipe and significant NPT during drilling, whether due to shale instability, overgauge hole, or mud losses during in-fill drilling in 'matrix dominated' or naturally fractured formations.
These problems are more acute in tectonically stress regions, but also have significant cost implications in normal passive basins. Detailed drilling analysis and wellbore stability modelling leads to reduced drilling costs and improved HSE.
Completion Selection & Design (Sand Production and Sand Quantification)
The tendency of sandstone (and carbonate formations) to produce sand and solids during production affects the well productivity as well as the integrity and safety of the production system.
Determining the onset of sand production, as well as the sand volumes and sand rates during the life of the well, allows a sand management strategy to be adopted.
Sand Management optimizes the well lower completion (screens) selection, the production system design and well productivity by lowering CAPEX and OPEX, avoiding sand-related erosion and production shut-downs.
Tight Oil & Gas Production (Unconventionals & Shale)
Geomechanics is a fundamental part of tight oil and gas production, from the stress orientations and magnitudes for fracturing, to the formation strength, stiffness and brittleness from completion interval selection.
Accurate geomechanical characterization is key to a successful tight oil and gas appraisal and development.
Bakken Shale Map From National Geographic
Enhanced/Improved Recovery (EOR/IOR)
The Injection of fluid, from PWRI, waterflooding to gas injection, is limited by the fracture gradients and the thermal effects on the reservoir stresses.
Detailed stress analysis at the start of a development allows optimum well placement to avoid water recycling and low sweep efficiency, improving the economics of EOR/IOR schemes.
Reservoir Compaction and Surface Subsidence
A combination of field depletion in high and moderate porosity formations results in reservoir compaction and transfer of the deformation to the surface. This is commonly accompanied by shear of the casing strings and well integrity failures both in the overburden and in the reservoir.
HP/HT Developments and In-fill Drilling
The high pressures and temperatures in HP/HT fields result in narrow initial drilling windows, making well planning difficult. As the fields deplete in-fill drilling can become more challenging, leading to excessive mud losses and/or kicks. These in-fill drilling challenges are also observed during depletion of normally or moderately overpressure formations.
Geological complexity exacerbates these problems, as in the vicinity of salts diapirs, or in tectonically folded and faulted regions.
Research & Technology Development
Technological innovations drive improved reservoir characterisation, production, recovery and safety.
Addis & Yassir have a track record of technology development and field applications to improve hydrocarbon reserves identification and production, from within operating companies and R&D organisations.
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