Drilling rig frame analysis

The object for verification analysis is the supporting metal structures of the drilling rig. Among others, the task was to perform the analysis of bearing structures of the drilling rig in LIRA-FEM software and determine the deformations and forces in the elements, etc.

Brief description and purpose of the facility

Initial data

The object for verification analysis is the supporting metal structures of the drilling rig, hereinafter referred to as the drilling rig.

This report was commissioned by Cleaver LLC to assess the load-bearing capacity of the metal structures of the drilling base and tower to ensure safe operation.

The contractor of the work was the organization ProjectService LLC, INN (tax code) 7451341310

Technical Manager Korzhuk Dmitry
Head engineer Laziuk Vladimir
The software that was used - LIRA-SAPR
Number of finite elements 89630

Objectives of the work

  • Determination of loads acting on the drilling rig in accordance with the regulations API 4F-2008-Specification for Drilling and Well Servicing Structures, SP 20.13330.2016 SNiP 2.01.07-85 Loads and efforts, GOST R ISO 13626-2013;
  • creation of the design model in LIRA-FEM in accordance with the customer's drawings for the main load-bearing metal structures of the drilling base and tower;
  • performing the analysis of bearing structures of the drilling rig in LIRA-FEM and determining deformations and forces in the elements;
  • checking the cross-sections of the main load-bearing structures of the drilling rig in accordance with the regulations SP 16.13330.2011 Steel structures;
  • check of the most loaded and critical joints of the structure (the list is determined by the drawings of the structure) in accordance with the regulations SP 16.13330.2011 Steel structures;
  • assessment of bearing capacity of metal structures of the drilling rig to ensure safe operation;
  • issuing recommendations on strengthening the bearing metal structures of the drilling rig to ensure safe operation of the structures (if necessary).

Information about the analysis process

The set of works performed in the scope of the technical task included:

  • familiarization with technical documentation of the drilling rig;
  • determination of the loads acting on the drilling rig;
  • determination of the areas of the rig that are affected by the loads;
  • compilation of load combinations options;
  • creation of design model in LIRA-SAPR;
  • implementation in the design model of the results obtained in steps 2-4;
  • performing the analysis and checking the sections of the main load-bearing structures of the drilling rig in accordance with the regulations SP 16.13330.2011 Steel structures;
  • processing of the analysis results and preparation a conclusion based on the results of the analysis.

The drilling rig analysis was divided into 2 parts: the first part - the tower with lifting devices, included in a separate design model, and the second part is the base of the lifting device, included in a separate design model. The forces from the lifting devices tower supports were transferred to the base of the lifting device. Wind loads acting on the rig were considered with a pulsation component. Almost all elements of the drilling rig were modeled with bar finite elements (FE). Other elements of the drilling rig were modeled by plate FEs, namely: parts of spars with variable cross-section, main beams of the working platform (central frame), sub-rotor beams and guide beams of the track.

Purpose of the facility

Drilling rig with lifting capacity of 200 tons with electric drive and echelon arrangement of blocks is designed for drilling of oil and gas wells with conventional depth up to 3200 m with the possibility of using top drive.

The drilling rig can be used in macroclimatic regions with moderate climate -U, category 1 according to GOST 15150-69 (-45º +40º) at fields with hydrogen sulfide content less than 6%.


Analysis and selective results

Analysis and selective analysis results for tower and lifting device

3D view of design model of the tower and lifting device

3D view of design model of the tower and lifting device

Load combinations for case 1a

Load combinations for case 1a

Displacements along the X axis

Displacements along the X axis, mm (13...15 comb. according to Fig. 1.22)

 

Displacements along the Y axis

Displacements along the Y axis, mm (13...15 comb. according to Fig. 1.22)

 

 

Assembly stage 2

Beginning of the lifting, the tower has detached itself from the temporary supports.

Load combinations for assembly case 2

Load combinations for assembly case 2

Displacements along the Z axis for assembly case 2

Displacements along the Z axis for assembly case 2

 

Analysis and selective analysis results for the lifting device foundation

 

3D view of the design model of the lifting device foundation

3D view of the design model of the lifting device foundation

 

Combinations of block 1b

Combinations of block 1b (39th...42nd loads in the table - combinations transferred to lifting device base from the tower with lifting device)

 

Spars displacements (Z) from 9th combination (maximum)

Spars displacements (Z) from 9th combination (maximum)

 

Rotor beams analysis

Rotor load on rotor beams (200 tf applied)

Rotor load on rotor beams (200 tf applied)

Cross-section numbers of the elements of the center and two side frames

Cross-section numbers of the elements of the center and two side frames

 


 

Analysis and selective analysis results for the rail track beam

3D-     .png

 

3D view of the track beam without top plates

3D view of the track beam (with and without top plates)

Diagram of load application from helical supports to the beam (for example 140 t and 72 t, combination 3)

Diagram of load application from helical supports to the beam (for example 140 t and 72 t, combination 3)

Soil stiffness is given via Pasternak subgrade moduli C1 and C2. C1 is approximately assumed to be 300 MN/m3 for both hard and semi-hard clay (as C1 increases, soil pressure increases as well). 2=900 MN/m. Under these conditions, we determine the ground pressure from the combinations of loads 1), 2) and 3).

 

See figure below for ground pressures for combinations 1), 2) and 3):

Contour plots of ground pressure (kg/<sup>2</sup>)   F<sub>1</sub>=72 t, F<sub>2</sub>=36 t

Contour plots of ground pressure (kg/2) F1=72 t, F2=36 t

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