The ROGTEC Interview: Mikhail Vilkov, Deputy General Director – Chief Engineer of RBU Russia, ERIELL Group

A year ago, ERIELL Group broke a number of records in drilling the first 1km horizontal well at the the Urengoyskoye oil and gas condensate field in the Yamalo-Nenets Autonomous District. The well was drilled in the Achim deposits. During drilling, we broke our own records for both drilling time and performance. The Company’s next success was the completion of two wells at the end of June. They were scheduled for completion within 76 days and 70 days, but were 24 days and 30 days ahead of time, respectively. And for the first time, completion assemblies for multistage hydraulic fracturing were used, and 3-stage hydraulic fracturing was performed in the Achim deposits.

M. Vilkov, Deputy General Director – Chief Engineer of RBU Russia, ERIELL Group.

Mikhail, drilling a well in 76 days became the ambitious time goal for the company for well delivery. What services were provided in these 76 days, and how much time did it take to drill the well?

ERIELL Group actively uses the early drilling program system, which allows us to reduce the time we take to drill wells, and therefore reduces the costs for our clients. The essence of this program is that the first part of the well is drilled with a light-duty drill rig such as the ZJ20, and the heavy-duty drilling rig is mobilized afterwards.

In 2013, the 340mm section of the surface casing for this well was drilled using our “early drilling method”. The well was then suspended. After resumption of the work, the net drilling time for three other sections (245mm service casing, 178mm production casing, and 114mm liner) was 334.5 hours, which makes it 10.6% of their total construction time.

Services such as directional surveying, gamma-ray logging, continuous mud resistivity, bearing and neutron density logging, caliper logging, and acoustic logging, were also provided during drilling. During well construction, bottom hole pressure and equivalent circulating densities were monitored remotely and online.

What methods and techniques did you utilize to reduce drilling time?

As usual, we used rotary steerable systems (RSS) to maximize drilling rates and to ensure a steady and stable well bore. RSS also allows us to more precisely target the pay zone. Use of bearing and neutron density logging allows us to determine the permeability and porosity of the rocks while drilling.

The application of a caliper logging tool is necessary to determine the intervals for setting the packers and packer pads for multistage hydraulic fracturing; the acoustic and neutron density logging tools enable us to the calculate and forecast the stability of the wellbore in the real-time, based on the calculations and strength of the formations.

Did you plan to drill the well 25% earlier than anticipated?

Initially, there was no fixed plan for a 25% reduction in drilling time, but we of course always try to do our best and achieve the most efficient drilling times for our clients. Effective, high-quality, and fast drilling, that eventually enables the operator to increase the efficiency and profitability of any project, is one of the ERIELL’s priorities. On this basis, we have has always been interested in keeping the construction ahead of the schedule.

This well became an important step towards our next milestone – at the end of July, we completed the next well at the ARKTIKGAZ project with a 1,049m horizontal section and total drilling time of 46 days instead of the planned 90 for a 5,058m section. This is almost twice as fast as the schedule.

What techniques did you utilize to ensure that you exceeded your time targets?

» Oil-based mud – OBM.

» Rotary steerable systems – RSS.

» Avoiding performance of geophysical studies upon completion of the drilling sections

» Incorporating all of the necessary geophysical techniques in the bottomhole assembly while drilling – by doing this we achieved effective data acquisition from our telemetry tools.

What problems did you encounter during your drilling ops and how were they overcome?

While drilling 222.3mm section (for 178mm production casing), there was a drop in the drift angle due to natural geological reasons. We resolved this problem by reducing inter well pumping and increasing the directional drilling rate. While drilling a 152.4mm section (for 114mm liner), we faced uneven bit rotation in hard interlayers in drilling sections between pay zones Ach3 and Ach4. This problem was resolved by changing the drilling parameters – top drive speed, load, and periodic liftoffs from the bottom.

What new knowledge did you acquire on this project that could be useful in the future?

Data acquired from the acoustic logging tool can be used to further correct the field development plan.

What was the extent of your involvement in multistage hydraulic fracturing process?

Preliminary operations for multistage hydraulic fracturing include assembly run-in and the activation of all elements. We successfully performed all of these operations.

What technical difficulties arose while drilling the horizontal section?

» Uneven of rotation (120%) while drilling hard interlayers and webs between the pay zones Ach3 and Ach4.

» Increased gas production while drilling and consequently a necessity to limit the inter-well pumping and to perform additional washovers prior to upbuilding.

Were you remunerated for early completion of the project?

Remuneration of the drilling crew and engineers involved in the project was based upon the results of their work under the bonus regulations of ERIELL Group’s RBU Russia.

How was HSE monitored during accelerated drilling process?

Our HSE Engineer was always present at the drilling site. Unscheduled checks of the functionality of the BOP and of the readiness to act of the drilling team members in the case of an emergency were also held. Gas shows and casing pressure were always closely monitored during the drilling of section 152.4 mm with intermediate washovers and a limitation of inter-well pumping when required.

Did you have problems with drill bit performance during this project?

Selection of a bit with the required specifications – MDi513LUBPX – was based on the field experience in the subhorizontal liners already drilled in the Achim deposits. The principal problem was the need to reduce the uneven rotation during drilling – and as explained above this was resolved.

How did rotary steerable systems perform during drilling?

The RSSs operated steadily during the drilling of this well. Use of RSS with a downhole motor (Vortex) is recommended to reduce the unevenness of rotation and acceleration in drilling of 152.4 mm and 222.3 mm sections.