Zahmuwl, Alhadi (Schlumberger) | Guedes, Carlos Eduardo (Schlumberger) | Bradford, Colin (Schlumberger) | Singh, Kamaljeet (Schlumberger) | Baumann, Carlos (Schlumberger) | Mostoufi Pour, Hooman (Schlumberger) | Sarian, Serko (Schlumberger) | Aboelnaga, Sharif (Schlumberger) | Smart, Moises (Schlumberger) | Sinclair, Garry (TAQA) | Adoga, Charles (TAQA)
We present a new perforating technology based on new wireline conveyance equipment and advanced downhole modeling to maximize operational efficiency in long pay-zones under all pressure conditions. Results of perforating jobs of long pay-zones carried out on wireline in very short times compete with traditional Tubing Conveyed Perforation (TCP) operations which take much more time. Also, perforating jobs with large gun sizes that until recently were not possible in a single run with traditional wireline conveyance, are now efficiently executed in a single run.
The new technology that allows conveying long lengths of perforating guns on wireline in a single run is based on four main elements: wireline systems with safe working loads up to 30,000 lbf, cutting-edge shock resistant mechanical weak points and disconnect systems, conveyance modeling, and an advanced transient dynamic modeling for perforating shock prediction. The perforating job design modeling is based on the reservoir zones and completion information, both a conveyance and a wellbore dynamics and shock simulation are carried out to determine the highest payload that can be more safely deployed per wireline run, and with the number of runs required, costs and risks are compared between wireline and TCP shoot and pull operations.
For a well with a 750 ft thick pay zone, a North Sea operator requested a comparison between this new wireline perforating technology and conventional electric wireline deployment in terms of reservoir productivity, risks, and operational performance. For this well TCP was not considered due to reservoir and operational risks and challenges. Compared to the conventional electric wireline conveyance this new perforating technology offers better efficiency with only two wireline runs using a cable with 18,000 lbf of safe working load and a 10 Kpsi surface pressure control equipment compared to 6 to 8 conventional runs. The longest run consisted of 388 ft of 3 3/8″ guns, which was a new world record on wireline, with energetic liner charges and dynamic underbalance to ensure maximum perforation tunnel cleanup and well productivity. The total operational time for the perforating job was significantly less than conventional electric wireline, which translated into significant rig time savings.
This paper demonstrates how the application of innovative technologies have minimized the risks of wireline conveyance with long and heavy perforating gun strings. We utilized well and reservoir information to design a more safe and reliable job execution, including prediction of perforating shock, tension profiles and wellbore dynamics. The new perforating technologies described in this paper have extended considerably the range of perforating jobs where wireline conveyance can be more efficient than traditional coiled tubing and tubing conveyed perforating.
The Bergermeer Rotliegend sandstone reservoir has been depleted by production. This has substantially reduced reservoir pore pressure and well deliverability. Pressure depletion has been accompanied by a decrease in minimum in-situ stress, resulting in a substantially sub-hydrostatic drilling fluid density required to enable drilling. As a result, Managed Pressure Drilling (MPD) using two-phase fluid has been chosen as the
enabling technology for drilling and completing initial wells for the Bergermeer Gas Storage Project. MPD for the Bergermeer wells is defined as the use of two-phase flow drilling fluid including nitrogen injection via a tieback casing to maintain bottom hole pressure below the anticipated reservoir minimum in-situ stress at or near hole depth. Using MPD technology in the Bergermeer Gas Storage Project will enable drilling the planned boreholes without exceeding minimum in-situ stress, minimizing the risk of differential sticking and drilling fluid losses if natural fractures are present. Reservoir pressure in the Rotliegendes reservoir was originally 238 bar (3451 psi) at 2100 m (6890 ft) subsea. By mid-2009, gas reinjection was started to bring the reservoir up to an operating pressure of 120 to 180 bar for gas storage operations. By May 2013, when the first of the new gas storage wells in the Bergermeer reservoir was drilled, the formation pressure had been brought up to 81 bar. Due to permitting restrictions, it was not possible to drill a test/pilot well before drillingthe first gas injection/production wells to physically determine formation rock strength. Therefore, a decision was made to drill into the 81-bar reservoir with a target BHP of 117 to 127 bar; this equated to an ECD of 0.57 to 0.63 SG. Dynamic formation integrity tests were performed to determine formation rock strength in a controlled manner using two-phase MPD techniques at predetermined depths in the reservoir. TAQA drilled two wells during May and June 2013, one S shaped vertical well and one horizontal well into the two depleted formations. This was achieved maintaining a constant BHP within the predetermined window using MPD with gasified fluid; in fact it was possible to drill the wells with a very stable BHP with a 0.6SG ECD. For the TAQA Bergermeer Gas Storage project, significant planning into the overall system design, equipment selection, techniques, procedures, and training lead to an operation where precise control of the annular pressure profile was achieved and maintained throughout the operation.
This paper presents a recent initiative by European operators for improving production enhancement via well interventions. It is based on the output of a benchmarking exercise into the performance of the various intervention activities. Data is historic and the aggregated and anonymised results of the benchmarking exercise are shared only amongst participating operators. Operators meet annually to discuss technical successes and failures and to identify potential areas for technical collaboration. Collaboration projects are only kicked off once win-win situations can be defined. Results to date indicate a broad range of performance impying ample opportunities for raising both operator and industry performance. The aim of this paper is to attract more participation in this European initiative and to raise interest for replicating it in other regions.