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Centeno, Manuel (Schlumberger) | Krikor, Ara (Schlumberger) | Herrera, Delimar Cristobal (Schlumberger) | Sanderson, Martin (Schlumberger) | Carasco, Anant (Schlumberger) | Dundin, Alexander (Schlumberger) | Salaheldin, Ahmed (Schlumberger) | Jokhi, Ayomarz (Schlumberger) | Ibrahim, Sameh (Schlumberger) | Wehaidah, Talal (Kuwait Oil Company)
The complexity of drilling highly deviated wells in Kuwait drives the need for step changing in the well construction mindset, where severe to complete loss of circulation in Shuaiba formation significantly deteriorate the shale layers in Wara and Burgan formations leading to uncontrolled wellbore stability events. Casing while drilling (CWD) and two-stage cementing with a light density cement slurry were introduced as a technology system to drill the highly deviated complex wells through unstable and highly fractured formations. Fit for purpose engineering processes, advanced software solutions, a tailored bit and a bottom hole assembly dynamically simulated for drilling stability and directional tendency behavior were designed. A special light density cement slurry with high compressive strength was also designed to tackle the lost circulation issues when cementing the casing string. The paper will describe how the technologies can work as one system to solve complicated wellbore problems and address the problematic challenges of drilling unstable shales and fractured formations in the same section of the wellbore. This strategy enabled a significant time saving compared to drilling the section conventionally, removing Non-Productive Time (NPT) resulting from additional trips, cement plugs, stuck pipe, and subsequent sidetracks.
Al-Enezi, Dakhil (Kuwait Oil Company) | Al-Mekhyal, Abdullah (Kuwait Oil Company) | Al-Wehaidah, Talal (Kuwait Oil Company) | Goswami, Bijan (Kuwait Oil Company) | Takate, Yogesh (Kuwait Oil Company) | Alam, Harry (Kuwait Oil Company) | Nair, Sajan (Kuwait Oil Company) | Al-Enizi, Talal (Kuwait Oil Company) | Dundin, Alexander (Schlumberger) | Wenang, Martine (Schlumberger) | Al-Hamad, Nasser (Schlumberger) | Juyal, Mukul (Schlumberger) | Hosein, Feraz (Schlumberger) | Centeno Acuna, Manuel (Schlumberger) | Saha, Santanu (Schlumberger) | Salaheldin Ibrahim, Ahmed (Schlumberger) | Albinali, Ebrahim (Schlumberger) | Alhazeem, Ali (Schlumberger) | Saleh, Rashad (Schlumberger) | Al Kubaish, Yasser (Schlumberger) | Mostafa, Shady (Schlumberger) | Mobasher, Mohammed (Schlumberger)
Almost all worldwide oilfields which have been producing for a long time have reached brown level of maturity. Given the foreseeable increase in global oil demand and consumption in the near future, operators need to be innovative in finding new resources and developing plans to meet the production demand. Oilfield service companies have parallely kept the pace by continuously improving their technologies and evolving their product offering to support activities from exploration to production phases.
Sabriyah Lower Burgan reservoir in North Kuwait has been producing for a long time after its discovery. Since oil production is mostly from massive and coal sand members for long time, exploitation of new reservoir is needed to sustain the field productivity. The non-traditional siderite layer (SID3) had been identified by Kuwait Oil Company (KOC) as a potential source of incremental oil production. The reservoir has a lower productivity index and cannot flow significantly in vertical wells. SID3 has a relatively thin layer (5-20 ft TVD) with high lateral variations and presence of regional coal, making it highly challenging for drilling operations.
There were many cases of wellbore instability while drilling wells in Lower Burgan in the past. Geological uncertainty generated by pinch out sand bodies in the reservoir section, led to scratching unstable shales and coal layers prone to collapse, thus resulting in stuck pipe events due to hole pack-off. Large volume and size of cavings, restricted circulation, high over pull, tight spots while tripping, and severe time-dependent wellbore instability due to shale sloughing contributed to the event and resulted in costly sidetracks.
The geomechanics study is a key technology in the oilfield industry to prevent wellbore instability, via optimization of well trajectory and proper mud weight selection. Application of the study outputs helps minimize drilling risk, diminish non-productive time and ensure well completion within the expected deadline. Horizontal well design is deemed as the most effective way to exploit the SID3 layer, and the application of High Definition Distance-To-Boundary (DTB HD) technology can help the operator mitigate geological uncertainties, maximize reservoir contact and hence boost production rate.
Integration of proactive Distance-To-Boundary technology, geomechanics study and meticulous pre-drill preparation have led to the successful completion of several horizontal wells in the SID3 layer. As a result, the operator gained a significant increase in oil production compared to the vertical wells. The well production also benefited from advanced completions technology with inflow control devices, handling other production related matters like presence of shale/silty layers for optimum hydrocarbon recovery. This proves that high-end technologies, coupled with multi discipline domain expertise and high-performance teamwork, is key to sustain the industry's ability to respond to the increase in global energy demand.
Al-Enezi, Dakhil (Kuwait Oil Company) | Al-Wehaidah, Talal (Kuwait Oil Company) | Goswami, Bijan (Kuwait Oil Company) | Takate, Yogesh (Kuwait Oil Company) | Muqaddes, Zahraa (Kuwait Oil Company) | Dundin, Alexander (Schlumberger) | Hariry, Haitham El (Schlumberger) | Hosein, Feraz (Schlumberger) | Torres, Maria Andrea (Schlumberger)
In close collaboration with the operator, third party suppliers and the integrated drilling service contractor the first Integrated Drilling Project in Kuwait started in March 2016. The project is being treated as a pilot to assess the value integration can bring to the operator by providing the expertise, new technology and processes for managing drilling risks and improving performance. The project scope includes the provision of all services, engineering and supervision for the well construction process under a lump sum model. The project had an original target start date of June 2016, a year after the contract award. However, in the current challenging oil and gas industry environment, coupled with the operator's ambitious plans to increase oil production, the requirement for drilling more wells to provide the necessary increase in oil output meant that an early start would help in accelerating oil production from the Sabriyah and Raudhatain fields. From the onset, the target was set for exceeding client expectations. It required a very detailed planning approach to avoid potential short-sighted risks that could lead to costly delays. This paper describes the success case of advanced planning of a fully integrated approach.
Three primary challenges were identified for the early startup, i.e. drilling rigs readiness, personnel and processes. For the drilling rigs readiness, the main issue was the utilisation of an interim rig requiring major equipment overhaul, including engines, top drive, mud pumps and drawwork, followed by an audit and certification. A specialised and dedicated team was mobilized to manage this operation successfully, and better support the rig contractor, including a rig contractor manager, rig managers, electricians and mechanics. Key project team members were brought in ahead of time, through careful selection to ensure the right competencies, according to the technical complexities and contract requirements. The team in place focused on implementing processes to accommodate operational and engineering optimizations as well as new technologies which could be applied from the first well, in order to improve well contruction cycle and deliver more wells in shorter time to the operator. This required collaboration from both teams including the integrated drilling service contractor and the operator. For ensuring the project readiness, a thorough process assessment was followed for each of the established milestones in the schedule. These assessments covered different functional areas including HSE, engineering, drilling services, third party providers, resources allocation and technology review including cost versus benefit analysis.
In result, close collaboration and hard work of integrated team including operator, third party suppliers and integrated drilling service contractor, enabled successful project start-up. The drilling operations commenced three months ahead of plan, exceeding expectations of all project stakeholders.
Al-Enezi, Dhakil (Kuwait Oil Company) | Goswami, Bijan (Kuwait Oil Company) | Takate, Yogesh (Kuwait Oil Company) | Al-Wehaidah, Talal (Kuwait Oil Company) | Jokhi, Ayomarz (Schlumberger) | Ghoneim, Osama (Schlumberger) | Karuppiah, Venki (Schlumberger) | Nair, Prakash (Schlumberger) | Hassan, Said (Schlumberger) | Helal, Karim (Schlumberger) | Dundin, Alexander (Schlumberger) | Djohor, Mohamed (Schlumberger) | Ibrahim, Sameh (Schlumberger) | El Hariry, Haitham (Schlumberger) | Saleh, Rashad Mohiey (Schlumberger)
A polycrystalline diamond compact (PDC) bit was used to drill a northern Kuwait well. The typical casing design for this field calls for the 16-in. section to be the longest section in the well, which extended from 1,230 ft to 6,000 ft for a total of 4,770 ft in this particular well. The formations drilled in this section were mainly comprised of carbonates interbedded with shale. The first 2,000 ft of the section was highly interbedded with hard and soft layers of carbonates with the unconfined compressive strength ranging from 6,000 psi to 30,000 psi. Additionally, the remainder of the section had hard stringers with unconfined compressive strength up to 30,000 psi. Such highly varying and highly interbedded formations tend to damage the PDC cutters because they are more susceptible to impact damage. For this reason, roller cone bits with tungsten carbide inserts (TCI) are preferred and are typically run in this section. However, the rate of penetration (ROP) significantly decreases when the TCI bits drill through the hard formations. For this reason, the operator and service provider established an objective to design a PDC cutting structure that would efficiently drill through the hard interbedded formations and complete the section in one run, achieving higher ROP than was achieved with the TCI bits in the offset wells.
Based on the formation strength information available, the decision was made to initially use a 6-bladed 16-mm cutter. The service provider then recommended using conical diamond elements (CDEs) and placing them behind the primary PDC cutting structure. The conical shape of the CDEs penetrate the high-compressive-strength rock, effectively weakening the formation with a plowing mechanism. Furthermore, the CDEs also protect the PDC cutting element from impact damage. A high-performance motor was also recommended to reduce stick-slip. A finite element analysis (FEA)-based modeling system was used to comprehend the dynamic behavior of the bit and bottomhole assembly (BHA) design. The most efficient bit design was selected, and changes in the BHA were recommended to deliver the most stable and optimized drilling system. A detailed drilling parameters sensitivity analysis was performed, and a driller's parameter plan was prepared to provide enhanced drilling parameters for mitigating downhole vibrations.
As a result, the CDE bit drilled the entire section, achieving an increase in on-bottom ROP by 24%. In the hard formation—where the ROP of TCI bits would typically decrease—the CDE bit drilled at twice the normal ROP.
The CDE bit technology proved to be efficient in what was previously thought to be a roller cone application. By reducing the drilling hours needed to complete the entire 16-in. section, the CDE bit saved the operator 3.5 days of equivalent drilling time.