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20.10.2016

Enquiry: drilling and completion technique of horizontal wells

Volumes of horizontal wells drilling in Russia increase. Representatives of leading oil service companies told OGJRussia about the main technologies used in well construction.

Emil Kuliyev, Technology Manager for controlled directional drilling of "Targin" company, answers:

Which drilling and completion techniques of horizontal wells, including large step out, are the most relevant nowadays?
Important today:
  • reducing the cost of the well construction;
  • bringing production parameters to maximum rates;
  • more complex wells drilling.
  • a range of technologies is used to address these challenges.
1) Drilling of horizontal wells using the rotary-driven systems. Due to the complexity of horizontal wells profiles the probability to face a problem of failure to transfer weight to the bit increases during drilling using the downhole drilling motors.
For horizontal wells with a large step out non-uniform rotation of the BHA becomes a problem. The optimal solution is to use RSS. This technology allows drilling with constant rotation, moreover, improves the condition of the wellbore and drill cuttings.

2) Another key problem of horizontal wells drilling is a low thickness of productive formations (in some cases 0.5 to 1 m). The solution of this problem is the inclusion of logging tools (LWD) in the BHA while drilling in conjunction with geological support service (geosteering) in the real time.

3) To improve the quality of drilled wells the telemetry equipment with hydraulic communication link is used allowing the real-time data transfer at a rate of up to 3 bps. Also, the application of multiple sonde devices for conductivity MWD allows for precise wells placement and navigation in complex reservoirs by direction and distance determination to formation boundaries in the real time.
This complex of solutions allows staying within the productive zone, adjust the trajectory in the real time, assess porosity & permeability and geomechanical properties.

About requirements for drilling rigs, rock cutting tools and drilling fluids used in the construction of horizontal wells

Despite ample competition in the industry, high maintainability and intelligence of drilling process using modern drilling rigs is a general trend.
Their main criteria:
  • portable drill units of high lifting capacity, equipped with top power drives, special pipe elevators, circulation system, which provides the necessary cleaning, withstanding high loads and pressures;
  • provision of high maintainability of drill unit, i.e. the availability of its assemblies for maintenance and repair; the ability to control the technical condition and replacement of wearing parts and assemblies;
  • use of less metal-intensive drill units in total to reduce the time required for mobilization;
  • use of powerful mud pumps with improved capacity.
Drills reinforced with polycrystalline diamond composites (PDC) are characterized by a unique cutting surface, which allows effective drilling at limited torques and low hydraulic power.
Disadvantages: A large number of drill units in Russia posses limited capacities in drilling due to the technical condition of drilling equipment that is not always allows utilizing the full potential of the conventional PDC bits.

Oil&Gas Journal Russia, No.10, 2016

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