Achieving Clean Environment by Attaining Zero Disposal in Surface Pits in PNZ Wafra Fields by Disposing Produced Water through Injection/ Salt Water Disposal Mega Wells Completions

Shahid, Mohammad A. (Kuwait Oil Company) | Remila, Gamal Okby Abdel (Saudi Arabian Texaco Inc.) | Weston, John (Kuwait Oil Company)


Abstract The PNZ (Partitioned Neutral Zone) has four onshore producing fields bordering Kuwait and Saudi Arabia and is being operated by Joint Operations of Kuwait Oil Company and Saudi Arabian Texaco. The four fields are Wafra, South Umm Gudair (SUG), South Fuwaris and Humma. The majority of production in the PNZ comes from the Ratawi Oolite in the Wafra and South Umm Gudair fields. Production from these fields began in the early 1950s and as maturing of these fields with the passage of time the associated water production has significantly increased which has resulted an environmental hazard in handling and disposal of this vast produced water. This challenge has been met in the past utilizing first surface evaporation pits and then augmented with peripheral water injection into the Ratawi producing reservoir. Today JO is meeting this challenge with the innovative method of horizontal Mega disposal wells completed in the karsted Shuaiba formation. These horizontal Mega wells are capable of taking up to +/- 80,000 BWPD on gravity feed. So currently, +/- 750,000 BWPD of produced water in JO is handled by injection of +/- 220,000BWPD into the peripheral of the Ratawi Oolite in the main Wafra field for the Pressure Maintenance Project (PMP) and through disposal of +/- 530,000 BWPD into the karsted Shuaiba formation. This paper highlights the integrated approach of studying the 3D Seismic interpretation, geologic, and engineering data resulted in the identification of Shuaiba karst Structure as the target disposal zone. The construction and completion of Horizontal Mega wells with 9 5/8″ tubing completion in the Shuaiba karst has resulted in achieving the company target of Zero water disposal in surface pits. It is a remarkable achievement and this technique is uniquely introduced for the first time in Kuwait and could have a potential to be used in the other areas in the Middle East Region. Introduction Until January, 1996 for SUG and January, 2000 for main Wafra about +/- 350,000 BWPD produced water in PNZ was disposed in evaporation pits. The surface pits are environmental hazardous and is undesired practice, therefore JO Management decided to stop this practice and move toward down hole water disposal schemes to achieve Zero Disposal of produced water in surface pits. Shuaiba and Zubair are Lower Cretaceous formations (Fig No.1) that have been penetrated by every Ratawi producer in Wafra Field. Drilling through the Shuaiba has been a concern of severe loss circulation and numerous bottom hole assemblies have been lost due to stuck and hence resulted most of these wells in side tracking the hole. After having study of the characteristics of the Shuaiba formation which represents as wide spread with thick sandstone beds of the Zubair below and Wara / Burgan above. It is Dolomitic limestone, medium to coarse crystalline in texture. It is vuggy to cavernous at time and its thickness changes from 102–180 ft and is spread through out PNZ Field in Wafra. These characteristics appealed to use this formation in benefit of disposing of vast quantities of water produced from different formations rather than disposing in surface pits.

  Geologic Time: Phanerozoic > Mesozoic > Cretaceous (0.55)
  Oilfield Places:

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