Successful Drilling Longest Horizontal Sour Gas Well
Authors: Aladsani Amna , Aranda Jose , Ahmed Mula , AL Qallabi Salah , Bankole Ibukun , Ahmed Mubashir , Dutta Ashim , Baslaib Mohamed , Aljeelani Omar , Alrumaithi Fahad , Al Hajri Zaher , Anwar Mohamed , Al Hammadi Adel Mohammmed 
Published: November 2018

Objective/Scope; ADNOC onshore has overcome yet another challenge in drilling longest horizontal well 10,000 ft in aggressive environment having ±30% H2S and ±10 CO2 with reservoir temperature around ±300°F. This project is part of the country strategy in meeting energy growth in sour gas wells for the coming future development.

Methods, Procedure, Process; the strategy is to enhance the well productivity by minimizing the footprint and drilling long horizontal well in harsh environment by achieving maximum accessible reservoir contact. A detailed well design was generated for each zone separately that touched different aspects from the planning phase to the execution and production in safe operating manner. It required an integrated approach bringing together many different technical and operation solution to achieve the drilling of long horizontal well. The well design was reviewed at each step was agreed

One the challenges to start drilling Sour Gas exploration well was penetrating multiple high temperature high pressure reservoirs with minimum geosteering to maintain smooth trajectory thru the structure of the reservoir to enhance well accessibility intervention. The objective was achieved by using rig capable to drill long horizontal well and drilling fluid which is compatible with logging tools that contains low salinity and low solids which assists in enhance the efficiency of the tools and achieving the target of drilling 10,000 ft horizontal sour gas well. The torque and drag calculation were reviewed and accordingly the drilling assemblies were selected. The well was completed with specialized material that will withstand the temperature and pressure changes during production and toxic environment having ±30% H2S and ±10 CO2. Moreover, this was also subjected to comprehensive review of HSE rules and regulations including safety and precautions while drilling.

Results, Observations, conclusions; Drilling and developing sour gas well with more than ±30% H2S and ±10 CO2 is an accomplishment. ADNOC onshore has studied the opportunity of drilling long horizontal well achieving maximum reservoir contact with the minimum footprintwhich will assist in reducing the cost of the future wells. Over the past years, ADNOC onshore has developed experience in drilling long horizontal wells in sour wells keeping in mind the safety and environmental aspects. A team of professional expects and support is available to achieve the objective safely & efficiently.

Novel/Additive Information; Developing sour gas wells has always been challenge due to the sour environment and accessing deeper horizon that require advance theology. Sour gas opens new marketing channels for ADNOC by maximizing the investment opportunities for the future investors and stakeholders. This will open new cost, maximizing the productivity without compromising the safety and allow drilling long horizontal wells in challenging atmosphere. The paper will describe the various issues faced while drilling sour gas well.