ANALYSIS METHOD30 INCH DRILLING CONDUCTOR

ANALYSIS

INTRODUCTIONConventional fixed platform facilities, even those in the deepest of waters, still rely upon relatively conventional marine conductors with above surface (deck level) wellheads through which to produce the reservoir gases and/or fluids. The conductor and well system is laterally supported by the surrounding structure at the plan bracing levels of the structureThe casing tubular will be predominantly loaded by a combination of self weight, weight of supported tubular and the wellhead loads.Lateral loads, which generate bending stresses in both the conductor and casing strings, are induced by environmental forces, which, for flexible systems, may be amplified by the effects of dynamic response. Due to its vital role, it is mandatory to check the integrity of conductor due to several load case which may occur during its service time.

SCOPE OF WORKAccordingly, the following analysis is a must in designing the conductor:

Conductor Strength And Stability Analysis Vortex Induce Vibration Analysis

REFERENCE API BULLETIN 5C3 SIXTH EDITION API RP 2 WSD API RP 2RD API RP 16Q DNV RP C203 AISC WSD 9TH EDITION

DRILLING SEQUENCE

DRILLING SEQUENCE

1. Run 30” Conductor2. Cut 30” Conductor Tubular3. Drill 26” hole 4. Run 20” casing5. Cut 30” Conductor and 26” Casing6. Drill 12-1/4” Hole and 17-1/2” Hole 7. Run 13-3/8” Casing8. Drill 12-1/4” Hole9. Run 9-5/8 Casing

WELL DESIGN MONTAGE

WELL DESIGN MONTAGE

CONDUCTOR CONFIGURATION

CONDUCTOR CONFIGURATIONConductor 30”Casing 26”Casing 13-3/8”Casing 9-5/8”

Dimension and Properties of Casing/Conductor Provided By SAKA:• OD 30” x 1” WT Conductor : XL-56 API 5L, SAW Pipe• 20” Casing : 133 ppf, K-55, L-80, Seamless Pipe• 13-3/8” Casing : 68 ppf, L-80, Seamless Pipe• 9-5/8” Casing : 47 ppf, L-80, Seamless Pipe

ENVIRONMENTAL LOAD1. Metocean data is obtained from available metocean data of the nearest location from the conductor. 2. Soil data is determined from the soil investigation on the location adjacent to the conductor.

The distance between the conductor location and the location of available soil investigation data is approximately 12 km.

STRUCTURAL MODELLING

Non-linear finite element models are developed considering a 30 inch conductor

The model extends from an effective fixity point below the seabed. Soil properties are modelled as p-y and t-zcurves based on soil data on the nearest location from conductor.

Allowances for marine growth and corrosion over the field life are also taken intoconsideration and should be appropriately modelled.

BOUNDARY CONDITION

The 30" conductor is grouted to the seabed. However, For conservative reason, we neglect the grout effect.

The top of conductor is assumed to be laterally restraint.

30” Conductor

Water Depth

Soil

Deformed conductor

CONDUCTOR STRENGTH AND STABILITY CHECKSStability is checked as the conductor will be under compression. The assessment involves: Combined axial loads due to the surface equipment and internal casingsBending loads induced primarily by the wave and current, misalignments, and also the eccentricity of the internal casings.The strength assessed on allowable stresses and principles from API RP 2A to determine acceptance.The most heavily loaded step in the drilling sequence is identified and used to determine the acceptability of the conductor system for the drilling phase and production phases

CONDUCTOR STRENGTH AND STABILITY CHECKS

Soil

Water Depth

Wave Force

Axial ForceTexas Deck

AXIAL LOAD ON 30” CONDUCTOR DURING DRILLING MODE1. 26” Casing2. Blow out Prevention (BOP)3. 13-3/8” Casing4. 9-5/8” Casing5. Diverter6. Bell Nipple7. Wellhead