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Tentative Technical Agenda
Wednesday, 14 May 2008
1300–1700
Session One: Enhanced Condensate Recovery in Fields with Depletion Drive
Session Managers: Stephen Collinson and V.E. Miskevich
At present, the number of gas condensate fields being discovered and put on production is increasing globally. Moreover, production is from deeper horizons, the formations are damaged more and the condensate content in formation gas is increasing. The optimization of the liquid condensate recovery from gas/condensate reservoirs has become increasingly important.
This session will focus discussion on (1) methods of increasing condensate recovery from gas/condensate reservoirs produced by pressure depletion, including reservoir pressure management, well placement and design, horizontal drilling, hydraulic fracturing and other stimulation technologies, and (2) the prediction of condensate recovery for such methods.
Main topics for the session:
- Main trends of depleted gas condensate field development optimization
- Optimization of production, well placement, formation penetration, multilayered zones accounting, reservoir heterogeneity
- Provision of gas production uniformity
- Horizontal wells: can these provide an enhanced condensate recovery technique?
- The influence of well productivity on condensate recovery: economics or technology
- Hydraulic fracturing and other stimulation techniques
Thursday, 15 May 2008
0900–1200
Session Two: Cycling Process
Session Managers: Frode Lomeland and S.M. Lyutomsky
Condensate recovery factor from pure pressure depletion varies from 70 to 40 %. By maintaining reservoir pressure, or delaying the pressure drop, it is possible to improve the condensate production rate and the ultimate recovery factor. Re-injection of dry hydrocarbon gas (where most of the heavy and intermediate components are removed) is the conventional technique used to improve condensate production rate and recovery (the re-cycling process).
Developing a gas condensate field raises many questions. Does your gas condensate reservoir contain sufficiently rich (or wet) gas for a re-cycling strategy? Should you start re-injection at once and keep the pressure high, or should you postpone investment in re-cycling equipment and keep the pressure just above dew point pressure? When do you stop re-cycling, and start pressure depletion and export sales gas. The competition between income from liquid and income from sales gas, naturally leads to the question whether you should inject nonhydrocarbon gas instead of hydrocarbon gas. The latter can pollute your sales gas, but it can be left in the reservoir at abandonment of the field without loss of income. Associated issues include break-through of injection gas, recycled gas sweep efficiency, well count and well locations. A subsurface team must consider all these issues.
Main topics for the session:
- Is pressure maintenance or sweep efficiency the key to success?
- The influence of well count and well location on sweep efficiency
- Decision criterion to be used:
- Optimal dry gas returning ratio
- Net present value
- What kind of reservoir simulator should be used?
- Black oil or compositional formulation
- Streamline or grid block formulation
- Injection of non-hydrocarbon gases:
- Is pressure maintenance using N2, CO2 or flue gas an option?
- Why don’t we inject flue gas?
- Modifications of the basic re-cycling method to improve the recovery process
1300–1600
Session Three: Flooding as Gas Condensate Recovery Enhancement
Session Managers: S.V. Kolbikov and V.I. Cholovsky
For several decades, waterflooding of gas condensate fields has been considered a perspective technique for reservoir pressure maintenance and, hence, condensate recovery enhancement. The experience of gas condensate field development at natural water drive shows that condensate losses together with gas trapped in flooded zones, as a rule, are compensated by decrease of condensate losses caused by retrograde condensation due to formation pressure depletion. Nevertheless, so far no project on water injection has been implemented because of well-grounded fears that producing wells can be put out of operation due to breakthrough of injected water. For the same reasons, different combined techniques of gas condensate formations treatment were not implemented: water gas treatment by injecting water and dry gas, dry gas rim formation by water injected into formation. Today, opened deep (below 3000 m) gas condensate reservoirs with high CGR and high formation fluid density due to reservoir conditions makes flooding techniques more effective and attractive to enhance condensate recovery.
Main topics for the session:
- Condensate recovery factor at natural water drive
- Artificial water flooding of gas condensate reservoirs: pro and contra
- WAG and other types of combined water and gas injection
- Lift methods in flooded wells
Friday, 16 May 2008
0900–1200
Session Four: Can retrograde condensate be recovered from depleted reservoirs?
Do we understand dispersed hydrocarbon liquids in gas condensate
reservoirs?
Session Managers: Tom O’Gallagher and N.V. Dolgushin
When the reservoir pressure is depleted to below dew point, retrograde condensate is dropped in the formation. The condensate saturation in porous medium becomes significantly lower than the critical saturation, causing the condensate to loose mobility and liquid drop out occurs. Can we re-mobilize this condensate? Can we extract retrograde condensate from reservoirs of partially or fully depleted fields? Is it possible to mobilize condensate by increasing the hydrocarbon liquid saturation in porous medium back up to critical values by injecting working agents into formation? Or is another option the evaporation of intermediate or heavy components of retrograde condensate so it is absorbed into the injected working agent and then transported in a gas phase to producing wells? The solution of all these issues will determine possible techniques of condensate recovery, dropped in formation.
The other important aspect of condensate recovery problem is the presence of dispersed hydrocarbon liquids, formed during accumulation and reformation of gas condensate deposits.
Among main topics for the session the following are included:
- Retrograde condensate mobility and possible techniques to improve its mobility
- Retrograde condensate displacement by injection of liquefied hydrocarbon agents
- Cycling-process efficiency in depleted gas condensate formations
- Is it possible to extract retrograde condensate from depleted gas condensate formations?
- Dispersed hydrocarbon liquids–myth or reality, their influence on condensate recovery factor
1300–1600
Session Five: Gas Condensate Field Development in Difficult Environment
Session Managers: M.A. Komin and Piet Van-der-Hem
A significant part of gas condensate reserves are contained in fields that can be classified as difficult to development. For example, deep gas condensate deposits with high pressure and temperature (HP/HT), deposits with abnormally low reservoir properties or deposits confined to fractured porous reservoirs. Complex behavior of gas condensate systems at HP/HT conditions creates additional problems for field development using a depletion tenchique (as a rule, causing significant condensate drop-out), and high formation pressures impose specific restrictions on re-cycling process performance.
Low reservoir pressure can cause low well productivity and high abandonment pressure, and therefore reduces current and ultimate condensate recovery. High heterogeneity of formations and presence of conjugated fractures negatively impact condensate recovery during depletion and reduce the effectiveness of reservoir-pressure maintenance.
High content of acid components in formation systems is another factor that complicates gas condensate field development and has a direct influence on the development process and selection of the stimulation technique.
Thus the discussions will be focused on:
- Abnormally high pressures, problems and solutions
- Excessive temperatures, problems and solutions
- Fractured reservoirs
- High content of acid components (CO2 and H2S)
