Investigation Of The Impact Of Condensate Blockage On Well Productivity In A Tight Gas Condesate Reservoir-Case Study Of Tawes Field

Advanced Well Completion Strategies to Improve Gas Production Deliverability in Marginal Tight Gas Reservoirs from an Onshore Abu Dhabi Gas Field

10.2118/207481-ms ◽

2021 ◽

Author(s):

Hajar Ali Abdulla Al Shehhi ◽

Bondan Bernadi ◽

Alia Belal Zuwaid Belal Al Shamsi ◽

Shamma Jasem Al Hammadi ◽

Fatima Omar Alawadhi ◽

...

Keyword(s):

Hydraulic Fracturing ◽

Horizontal Wells ◽

Gas Production ◽

Abu Dhabi ◽

Tight Gas ◽

Production Rates ◽

Well Productivity ◽

Gas Saturation ◽

Well Design ◽

The Impact

Abstract Reservoir X is a marginal tight gas condensate reservoir located in Abu Dhabi with permeability of less than 0.05 mD. The field was conventionally developed with a few single horizontal wells, though sharp production decline was observed due to rapid pressure depletion. This study investigates the impact of converting the existing single horizontal wells into single long horizontal, dual laterals, triple laterals, fishbone design and hydraulic fracturing in improving well productivity. The existing wells design modifications were planned using a near reservoir simulator. The study evaluated the impact of length, trajectory, number of laterals and perforation intervals. For Single, dual, and triple lateral wells, additional simulation study with hydraulic fracturing was carried out. To evaluate and obtain effective comparisons, sector models with LGR was built to improve the simulation accuracy in areas near the wellbore. The study conducted a detailed investigation into the impact of various well designs on the well productivity. It was observed that maximizing the reservoir contact and targeting areas with high gas saturation led to significant increase in the well productivity. The simulation results revealed that longer laterals led to higher gas production rates. Dual lateral wells showed improved productivity when compared to single lateral wells. This incremental gain in the production was attributed to increased contact with the reservoir. The triple lateral well design yielded higher productivity compared to single and dual lateral wells. Hydraulic fracturing for single, dual, and triple lateral wells showed significant improvement in the gas production rates and reduced condensate banking near the wellbore. A detailed investigation into the fishbone design was carried out, this involved running sensitivity runs by varying the number of branches. Fishbone design showed considerable increment in production when compared to other well designs This paper demonstrates that increasing the reservoir contact and targeting specific areas of the reservoir with high gas saturation can lead to significant increase in the well productivity. The study also reveals that having longer and multiple laterals in the well leads to higher production rates. Hydraulic fracturing led to higher production gains. Fishbone well design with its multiple branches showed the most production again when compared to other well designs.

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Evaporative Cleanup of Water Blocks in Gas Wells

SPE Journal ◽

10.2118/94215-pa ◽

2007 ◽

Vol 12 (02) ◽

pp. 209-216 ◽

Cited By ~ 15

Author(s):

Jagannathan Mahadevan ◽

Mukul Mani Sharma ◽

Yannis C. Yortsos

Keyword(s):

Capillary Pressure ◽

Damage Zone ◽

Low Permeability ◽

Tight Gas ◽

High Permeability ◽

Water Displacement ◽

Gas Wells ◽

Well Productivity ◽

Gas Expansion ◽

The Impact

Summary The flow of a gas toward the wellbore of a production well will result in the evaporative cleanup of water blocks, if the latter exist. This occurs primarily due to gas expansion. This paper presents for the first time a model to calculate the rate at which such water blocks are removed, for either fractured or unfractured gas wells. The model allows us to compute the impact of evaporative cleaning on well productivity. The removal of water first occurs by gas displacement. Evaporative cleanup is caused by gas expansion. The resulting saturation profile is qualitatively different for low- or high-permeability rocks. As a consequence, the increase in gas relative permeability, or the well productivity, with time can vary depending on the rock permeability and the well drawdown. High-permeability (e.g. fractured) rocks clean up significantly faster. By contrast, low-permeability unfractured wells may require a very long time to clean up. Large pressure drawdowns, as well as the use of more volatile fluids, such as alcohols, also result in faster cleanup. A distinctive feature of the work presented is that the model equations are formulated and solved completely without the assumption of skin factors for the damage zone. Thus, the prediction of cleanup rates can be made more accurately. Introduction Water blocks in low-permeability rocks clean up much more slowly than those of higher permeability because of the smaller pore sizes and the consequent higher capillary entry pressures (Mahadevan et al. 2003). In particular, water blocks in tight gas sands are not easily cleaned up, especially in cases where the reservoir pressures are too low to initiate flow. Past studies (Tannich 1975; Holditch 1979, Parekh and Sharma 2004) have reported the effect of water displacement by gas in the cleanup of water blocks in gas wells. They showed that when the drawdown in the gas well is significantly larger than the capillary pressure, cleanup is faster. However, in cases where the drawdown becomes comparable to the capillary pressure, as is the case in depleted tight gas reservoirs, displacement alone is not sufficient to remove water from the near-wellbore region. Subsequent water removal occurs by evaporation. The flow of a fully saturated compressible gas through a water-saturated porous rock induces evaporation. Roughly, this is because the volume of the gas, and hence its capacity for water content, increases as pressure declines. In past studies, the impact of evaporation caused by the flow of gas has been neglected. The focus of this paper is precisely on this regime in gas wells, in which the drawdown is comparable in magnitude to the capillary entry pressure, and cleanup of water blocks is by evaporation.

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