First Application Drilling New Wells with HWU in Swamp Environment, Mahakam Delta

Tunu is a mature giant gas and condensate field locate in Swamp Area on Mahakam Delta, East Kalimantan, Indonesia. The field has been in developed for more than 40 years and considered as a mature field. As mature field, finding an economic well has become more challenging nowadays. The deeper zone of Tunu (TMZ) has no longer been considered profitable to be produced and the focus is shifted more on the producing widespread shallow gas pocket located in the much shallower zone of Tunu (TSZ). Facing the challenge of marginal reserves in the mature field, Pertamina Hulu Mahakam (PHM) take two approaches of reducing well cost thus increase well economics, improving drilling efficiency and alternative drilling means. Continues improvement on drilling efficiency by batch drilling, maxi drill, maximizing offline activities and industrialization of one phase well architecture has significantly squeezed the well duration. The last achievement is completing shallow well in 2.125 days from average of 6.5 days in period of 2017-2019. Utilization of Swamp Barge Drilling Rig on swamp area had been started from the beginning of the field development in 1980. Having both lighter and smaller drilling unit as alternative drilling means will give opportunity of reducing daily drilling rate. Hydraulic Workover Unit (HWU) comes as the best alternative drilling means for swamp area. In addition, fewer and smaller footprint equipment requires smaller barges with purpose of less civil works to dredge the river and preparing well location. Drilling with HWU project has been implemented at Tunu area with 5 wells has been completed successfully and safely. HWU drilling concept considered as proven alternative drilling means for the future of shallow wells development.

Research of the problem of optimization and development of a calculation method for two-stage chain drives used in heavy industrial vehicles in conditions of economic efficiency

The article is dedicated to the problem of optimization of chain drives of the drilling unit. At present, increasing the power per machine to the optimal limits, reducing the material and energy consumption per unit capacity of the machine, as well as operating costs are considered topical issues. The machines that are designed and constructed to optimal limits must be very powerful and productive. The machines that are applied to perform drilling works in the oil and gas industry must be easy to operate, reliable and have ability to operate for a long time. When constructing such machines, their being lightweight, economical, as well as their preparation in a short time and at low cost should be taken into account in advance. In order to ensure the reliable operation of drilling rigs, it is more expedient to apply chain drive in their mechanical transmission. First of all, the application of chain drive in drilling units and hoisting mechanisms is considered. Then a calculation method was developed for the chain drives of the drilling unit used in deep exploration wells and the exploitation of wells, and, accordingly, the calculation of the chain drive was carried out. The chain drive consists of drive and driven sprockets and a chain that encompasses the sprockets and engages in their teeth. Chain drives with several driven sprockets are also used. In addition to the basic listed elements, chain drives include tensioners, lubricating device and guards. The chain consists of hinged links that provide mobility or “flexibility” of the chain. Chain drives can be performed in a wide range of parameters. The calculation took into account the quality of the material, the service life and durability of the chain drive construction

Dynamic Response of Drill Floor Considering Propagation of Blast Pressure Subsequent to Blowout

Explosions and fire have very critical safety hazard impacts on offshore oil and gas facilities since they are mostly located in remote areas and could induce serious environmental issues. Explosion risk assessment and structure blast analysis are essential for these production facilities, and research studies have been carried out. Explosion due to blowout during drilling operation is also a critical risk for drilling units, and this has not been researched much until the accident of the drilling unit in the Gulf of Mexico in 2010. This paper provides the risk and evaluation of explosion and structure under blast pressure during the drilling operation, whereas previous research studies have mainly been interested in process plants. This study suggests weight saving in drilling units through the consideration of the actual behavior of gas explosion. Weight saving is the priority of offshore unit design due to payload. This research also gives guidelines to select the material-grade-appropriate anti-explosion system through the comparison of several materials by design and result.

Stability Assessment of Drill Ship Using Probabilistic Damage Stability Analysis

Drill ship is a ship-shaped structure with a drilling unit at its center and with oil compartments, which is moored and kept in position using anchors. These ships should be capable of working in deep sea for a long time, hence affected by harsh ocean environment. Drill units are said to have greater heave motion, and the height of the derrick influences the vessel’s stability. MARPOL Oil Outflow Analysis is performed for damaged crude oil carriers or tankers and Mobile offshore drilling units (MODU) in damaged condition. In the present study, probabilistic analysis is performed on drill ship to understand its stability behavior under damaged condition. Stability assessments are carried out by considering single and multiple damage locations. Oil outflow analysis is carried out for different damage cases of oil tank. Probabilistic damage assessment is done for load cases up to 50% flooding, to obtain stability charts. These charts will be useful to understand variations in stability parameters under damaged conditions.

Experimental and Numerical Study of Horizontal Wave Impact Loads for a Semi-Submersible Drilling Unit

A semi-submersible drilling unit model was tested to estimate horizontal wave impact loads on vertical side of deckbox following the procedure recommended by DNVGL OTG-14. The present model test data show that there is clear difference in the relationships between upwell and horizontal wave impact pressure between near column/pontoon and around centerline. Near column and pontoon, not only is the maximum pressure much lower but the pressure increases more smoothly to its maximum value, compared to those of centerline. CFD simulations with focusing breaking waves have been made to examine the effect of wave-body interaction on horizontal wave impact on deck-box. The present CFD simulation results clearly show that the flows in front of column are strongly accelerated in vertical direction by blocking effect of column and pontoon, eventually producing strong run-up jets. The run-up jets in the present study are so strong that the direct impact of the incoming breaker on the wall does not occur, which leads to much smaller peak pressures, compared to those of centerline.