Ongc drilling manual

Test Cylinders to ensure that both Rams move simultaneously in the same direction. Fully extend Rams ready for Mast Snubbing. During this operation the Mast will Break over its center of gravity.

Continue retracting Rams, while taking up slack with Hook until pin connections line up. Pin the mast with AFrame on both sides. Attach Ramp to Setback Support. Sequence Three Fig. All pins have been fitted with Safety Clips. All draw works and stub section line guards have been fitted. The A-Frame Line guards should not be fitted at this stage.

Check that the bull line is reeved correctly. Slowly raise draw works with its power, ensure that the Rotary Beam connections line up and pin Rotary Beams to Setback Spreader. Pin all Rotary and Floor Beams to Setback and draw works.

Raise Travel Block and hang equalizer pulley and bull line in the Mast, remove from Hook. Or Lower to Drill Floor, remove and store Equalizer pulley and bull line.

Items a. Hookups dog house support, drill floor panels and other miscellaneous items. Remove bottom box rear extensions and also remove bottom box front extension DS for entry of BOP stack. After alignment, tighten the nuts. The Lowering Sequence is the reverse of the Raising Sequence. The main sequence is as below. Remove any additional items added after Erection, which might interfere with the Lowering procedure. Reverse Section F. Trolley Beams, Hoists and Trolleys.

Replace Line Guards at Stub and draw works Sheaves. Tighten block and check Lines. Unpin and lower draw works Lock Brace.

Unpin Rotary Beam Unit at draw works only. Unpin Rotary Floor Beams at Setback only. Cautiously lower the draw works.

Replace Line Guards. Tighten block and recheck bull lines. To lower Mast remove pins and extend Rams of snubbing unit while lowering the Hook, maintaining very little slack as Mast breaks over its Center of Gravity, continue to lower mast onto Mast horse.

Continue section D to A in reverse order for further de-rigging. Data used for replacement does not give any clue. Because some times line are replaced early due to incidental damage and some times lines are used beyond the time when they should be replaced.

There is no way of judging the remaining strength of a rusty rope, so it should be replaced. Especially areas adjacent to end connections should be examined closely for any corrosion. In coastal areas sling lines left hanging in the mast may become corroded and found unfit for further use. It is possible to establish sling line life expectancy in terms of number of locations on which it was used, as long as a set number of months were not exceeded.

But again this will not preclude the necessity of careful inspection. A line showing with broken wires should be replaced. A line with any material reduction of metal from abrasion should be replaced. A line showing kinking, crushing, or any other damage resulting in distortion of rope structure should be replaced. Replacement of lines based on normal life expectancy will provide some degree of safety, but due to which there should not be any laxity in sling line inspection.

Sling line should be maintained in a well-lubricated condition. The field lubricant should be compatible with the original lubricant. The object of rope lubrication is to reduce internal friction and prevent corrosion.

Preparation of spudding. Rig movement is within the radius of 20 Km. Rig equipment should be transported on above priority so that it is unloaded at appropriate place at new site. For sky top mast one more day is required due to its design. Type 1 crane capacity 75 Ton , Type 2 crane capacity Ton 5. Also 1 Truck is needed for miscellaneous items as per the requirement of rig In-charge. Any attempt to exceed these limits will jeopardize the safety of the crew and the unit.

Jacking and moving procedures must take into account the capabilities and limitations of the unit when sitting on bottom, when afloat, or under tow. All personnel operating the units equipment should read the Information and Operating Instruction Book published by the manufacturer. This book gives specific instruction on the operation and maintenance of the units machinery. Newly classed ABS jack up rigs have emergency power sources. Check the emergency power plant and all emergency systems at least once a week.

Emergency repair supplies should be on board, and be inspected periodically for quantity and condition. Switch fixed pins to OUT on all columns.

Confirmation of the pin situation from each column should be obtained with every pin change before proceeding with the jack-ing. This information should be obtained by telephone from personnel in each jack house. When all fixed pins are confirmed to be OUT, use the master jacking lever to raise the yokes lower the platform in unison one full, six-foot stroke. During the stroke, the aluminum wedges can be removed. NOTE : The automatic leveling device incorporated within the jacking system should keep the three yokes in line to: 1 inch relative to column 1 during the power stroke.

During the power stroke and when about 10 inches from the end of the stroke, switch all the fixed pins to the IN position on the console and continue jacking in the same direction. These pins will not move all the way in immediately as they are not centered over the respective pin holes, but the FIXED PIN OUT lights will go off and the pins will be loaded up against the columns ready to go into the column pin holes as soon as they become aligned.

If there is an indication of pressure decrease before a green light activates on any one column, jacking should be stopped until the cause of the problem can be determined such as a stuck fixed pin, a maladjusted limit switch, etc. When all fixed pins are IN and confirmed, switch yoke pins to OUT position on the console, and use the master jacking lever to raise the yokes transfer the platform load to the fixed pins , allowing the yoke pins to disengage themselves from the columns.

Switch yoke pins back to the IN position, again, about six inches before the end of the return stroke, and continue jacking until all yoke pins are IN as before and confirmed. Repeat steps 2, 3, and 4 as required to bring the platform down to the water. Before the platform enters the water, a platform weight summary and platform longitudinal center of gravity LCG calculations are to be made.

This is required for determining the amount of drilling water to be shifted in the platform in order to obtain even keel conditions when the mat is free and the unit floating. The method for adjusting the platform LCG to coincide with the floating longitudinal center of buoyancy LCB will normally be by shifting drilling water only. If feasible for the particular drilling unit and location, the derrick skid unit may also be moved to expedite the adjusting of the LCG. Continue jacking down until platform draft exceeds the calculated floating draft by two feet.

With this amount of excess buoyancy, the mat should free itself from the sea bottom, as can be observed by a decrease in platform draft and head end pressure on all three columns. If difficulty is encountered and the mat will not pull loose with two feet excess draft, provisions have been made for water to be jetted from the underside of the mat. The piping for this system terminates in column 1. Using the same action it took to lower the platform, raise the mat the desired clearance bottom to bottom for the move.

If it is desired to raise the mat up to the uppermost position 26" clearance between the molded platform bottom and mat deck , override the automatic shutdown at columns 2 and 3. This is accomplished by holding the override button down in the lower left corner of the console before the end of the last 46" stroke is reached.

When sufficient clearance between the bottom of the mat and sea bottom exists, pressure up the rod ends of all cylinders lower the yokes with both the fixed pins and the yoke pins engaged and the yoke down to about psi.

This will prevent relative movement between mat and platform due to wave action. If after a period of time the pressure decreases in the rod end of the cylinders, they can be repressured to psi.

All sounding tubes must be capped except, and only, when in actual use. Manhole covers into the inner bottom tanks must be bolted closed at all times unless access to a tank is necessary. Immediately upon completion of each job requiring access to any tank, the manhole cover must again be bolted closed.

While the unit is afloat, all manifold valves and all bilge control valves in the tank piping systems must be closed unless, and only when, they are necessary for system operation. Also, all plugs, caps, etc. All watertight hatches, vents, and companionways must be secured watertight while the unit is afloat except when in actual use. All watertight doors and thru-bulkhead vents are to be closed.

The preload dump valves must be closed at all times, both afloat and elevated, except during the actual discharge dumping of the preload. Rig movement and deck-loading conditions may determine the scope of work that can be carried out during rig move and positioning operations. Perform fluid end inspections on the mud pumps and change liners as specified in the well programme.

Reset relief valves pop offs of the mud pumps depending on the liner burst rating as required for the liner in use, settings are specified in the manufacturers recommendations pressure test to be recorded on a chart.

Perform inspections of all BOP equipment e. BOPs, safety valves etc. If possible pressure test these items with water. Service all standpipes, valves, chick sans, hoses, choke and kill manifold valves, and conduct pressure test of these if required. All mud handling equipment should be serviced including, shale shakers, mud cleaner, desander, desilter and mud mixing equipment.

The shale shakers should be fitted with the correct size of screen for the top-hole section as per requirement.

Check the calibration and function of all drilling instrumentation e. The first of which is to skid the cantilever and drilling package out to the desired operating position. Service hoses, electrical loops and cable trays will also be monitored to prevent damage to them. Once skidding of cantilever and drilling package is complete check that rotary table is positioned directly over the proposed well centre.

Secure the cantilever and drilling package to prevent any movement during the well. Install any drill floor access stairs, walkways and v-door ramp if removed for skidding. It also verifies that all equipment and materials required for the surface hole section are on board, certified and in good working order. A Rig Specific Procedure for handling the Master Bushings during drilling, running surface casing, BOP and diverter operations be in place and followed.

When rigging up to run 30" and 20" casing, the bushings not be removed until the shoe joint is ready to be run through the rotary table. A hole cover be in place when ongoing activities, associated with the removal and replacement of rotary table components, are suspended for any period of time. A pre-spud meeting be held with all personnel involved in the operation. Ensure that all the relevant fishing equipments are available. Consult with the Client and service personnel to verify the wellhead systems and stack up dimensions.

Specified quantities of mud chemicals, including barite and bentonite, should be on location. Sufficient spud mud, with the correct properties as specified in the drilling programme, should be mixed ready for use. Specified quantities of cement and additives should be on location. Drilling consumables for the first hole sections should be on location including but not limited to wellheads, casing and its handling tools, drill bits and nozzles of various sizes stabilizers, hole openers and reamers.

All drilling tools supplied by the Client should be checked for compatibility with the Contractors equipment e. This should include both drilling and fishing tools. Prepare the BHA, pick up, drift and rack enough drill pipe to complete the surface hole sections.

Making up and racking stands during drilling operations is not permitted. Measure the conductor pipe measurements to be checked by clients representative to determine the correct footage of hole to be drilled. Check all conductor handling equipment for certification and compatibility with the size of casing to be run. If casing is to be run using lifting eyes then check the slings shackles are available and are certified to the appropriate load rating. Check that there is sufficient oxygen and acetylene equipment ready to cut the lifting eyes.

Sizes of casing vary depending on the Clients requirements and well plan. The casing size referred to in this section is 30" as it is the most common; however specific requirements will be issued in the well programmed.

Initially it will allow a circulation system to be set up taking returns back to rig. It allows the diverter system to be hooked up. It also prevents surface sediments from sloughing and protects against rig foundation failure washout. Check the derrick, top drive, block, and crown prior to and after the hammering operations for any loose objects.

Paint the shoe joint white to assist with ROV observation. Run the 30" casing to one joint above the seabed then rig up the hammer and chaser joint. If available the ROV will observe seabed for obstructions prior to the 30" penetration.

All lifting gear on the hammer assembly will be checked for rating and certification. All shackles will be secured with split pins and checked periodically during the operation. To ensure the 30" is vertical, tag the seabed and commence driving at slack tide.

Record the rotary to seabed measurement and weight of 30" from rotary to seabed in the IADC drilling report. Once maximum bottom penetration is achieved from the weight of the 30" alone, allow the hammer and chaser joint to rest in the top of the 30".

Do not allow the hammer support slings to take load while driving, continue to watch them and slack off on the blocks simultaneously. Ensure that hammer operator is also monitoring the support slings, is situated next to the controls and is able to stop the hammer blows should the need arise.

Do not set slips on the 30" once driving has commenced. Rig down and layout the hammer then run in with a 26" bit and BHA. This may require the use of 30" elevators, pad eyes or a load ring on the 30". While drilling limit the ROP to prevent overloading of the annulus and do not drill further than the shoe. The 30" will not be driven if shallow gas is a potential problem unless the formations have been drilled and proven to be gas free.

In off-shore, drilling is much economical with jack-up rigs but their limited water depth capability generally ft. On the other hand, floaters, if equipped with dynamic positioning system are independent of water depth and seabed conditions.

Also in the water depth range of jack-ups floaters also provide a solution to some problems like punch through locations. However, the initial investment and the operating cost of floaters are much higher than that of a jack-up rig.

Drill ships are suitable for drilling in deeper waters beyond the limit of Jack-ups. They are suited in logistically difficult areas as normally they have high load carrying capacities. However, anchor moored type ships are not suitable for harsh environments as their response to hydrodynamic forces is not as good as compared to Semis. Therefore in harsh weathers, downtime tends to be much more on a drill ship than a Semi.

Otherwise, drill ships are more stable in terms of survival and station-keeping in adverse weather conditions as their CG is lower. The variable loads like casings, risers, tubulars, mud chemicals etc.

This keeps the CG at much lower level and imparts more stability to drillships. Drillships are normally cheaper than semi-submersibles for moderate environment areas. They can carry out exploratory drilling, development drilling on subsea templates and subsea completion of single wells.

Around half the length of columns is also submerged in water. Semis can be triangular, rectangular or pentagonal type. The most popular is rectangular design in which there are two bottom hulls each supporting 3 to 4 columns on which working deck is placed.

They are suitable for water depths from 30m - m. They are more suitable in areas with rough sea conditions and harsh environ-ments including icy seas. They are designed to minimise the impact of hydrodynamic forces on the vessel thus greatly reducing the heave as well as roll and pitch. This way, its response to hydrodynamic forces is excellent. But they are more prone to capsizing as the centre of gravity keeps on moving up with the addition of load on top deck during drilling operations which is inevitable.

This results in a drastically reduced deck load capacity as compared to a drillship. Semis are costly in operations but are a better choice for areas where harsh weather prevails for a longer period during the year. Suitable for water depth upto m. New ships are being designed which will be capable of anchor mooring in approx.

Turret moored rig are capable of reorienting themselves as per weather conditions using its turret and thrusters. They are self propelled and are suitable for areas with water depths greater than m, or lower water depths with harsher environments or locations which may require quick movement like frequent storms, or places with subsea pipelines, communication lines etc.

They are very costly to operate as fuel consumption is very high for DP system. Every casing string lowered in the well is terminated at the seabed except liner casing.

BOP stack generally 18 bore is lowered and installed at the seabed after 20" casing and once installed all the subsequent operations right up to abandoning of the well are carried through the stack. It has more functions and requires special handling system.

A string of risers about 20" bore is used which needs a special tensioning system to maintain constant tension for heave compensation. BOP control system is much more complex for remote operation and redundancy. Every casing string lowered in the well is brought up to the surface except liner casing. Dimensionally this stack is much smaller in size and has less no. The vessel moves to the new location. The vessel moves into position and the heading is adjusted depending on the prevailing sea condition.

The running of anchors begin with the help of anchor handling vessel. The anchors are laid as per a predetermined pattern, pre-tensioned and then slacked-off to the operating tension values. Final adjustment of heading and position is now made with the help of instrumentation. The vessel is now ready to spud the well. A temporary guide base is lowered to the seabed during the low tide with the help of guidelines.

The 36" hole is drilled 80 to ft. During these operations there are no returns of circulating fluid to the rig. This casing is strictly for the structural support and will not sustain any pressures. A permanent guide frame is secured with 30" casing head while running casing to guide the BOP stack on the well head.

Risers with a pin connector without BOP stack might be run with the diverter on top if shallow gas sands are likely to be encountered..

The diverter is required because the well can not be shut in on the 30" casing. In this case a pilot hole is drilled and then enlarged to 26" 20" casing is run with 18 well head on top with a running tool and drill pipes. The casing is cemented in place The 18 BOP stack is now run and latched on to the 18 well head. The riser and the BOP stack are retrieved. The process of pulling of anchors begins for an anchor-moored vessel while a D.

Penetration Test It is carried out to check the seabed formation to ascertain the depth of conductor casing so that it can safely withstand the weight of wellhead, subsequent casing and BOP. The sequence of operations in carrying out penetration test is as under: 1.

Bit and bit sub should be painted white for observation by ROV. Space out should be adjusted so as maintain jetting assembly and bit in the hole while making first connection. Open drill string motion compensator to full stroke and set pressure to compensate at Kgs.

Lower drill string until the bit is lost from view. This depth is known as murk line. Continue to lower the drill string until the bit takes Kgs of weight and does not settle any more. This depth is known as competent mud line. Initial WOB and flow rate should be low and be gradually raised one at a time when there is no progress. Penetration test should be continued without rotation up to the point of refusal. The point of refusal is the point where the formation can withstand 10 T of slack off.

Rate of penetration will be dependent on pump strokes mainly. Initial jetting starts with 20 SPM. Keeping parameters same gives a fairly god idea as to when formation begins to change. Plot a graph Depth vs. Based on depth up to the point of refusal conductor casing tally is made. Exploration Test Exploration test to confirm shallow gas presence when the drill string is positioned for jetting test off location is also conducted there. It is carried out 50 m down stream and down wind side so that if gas is encountered ship can be pulled upstream by anchors or using propulsion to move away from gas zone.

Gas plume in shallow gas occurrences has been observed to form a low angle of 10 at the wellhead. Based on this and wind direction location of this exploration test is decided. The exploration test must be carried out upto the sectional target depth of 26" phase.

Normally shallow gas pockets are observed from to m below seabed. Prediction of shallow gas by means of geo technical tools is not very reliable therefore, it is a standard practice to drill small size preferably 8 pilot hole. The requirement and procedure for drilling pilot hole for exploration test is as under:. Requirement A float valve should be installed in bit sub. As usual a Kelly cock should also be used to arrest gas flow in the pipe.

A minimum of twice the pilot hole capacity of kill mud 10 ppg should be kept ready. Cementing unit should be kept in readiness. Captain and marine crew be kept ready for moving rig off location if situation arises.

ROV should be stationed near the seabed. Procedure Normal drilling over this section will be relatively fast hence drilling should be done at a moderate rate so that minor gas flows if any can be identified with ROV. Always observe the well carefully for gas flow prior to making connection.

If minor gas shows are seen the bit is to be pulled off bottom and observe the well. If the gas stream continues at a constant rate or diminishes during the flow check then a further 3m can be drilled, circulate bottom up and observe the well.

This procedure to becontinued till such time that the gas streams is minimal. Once safe conditions have been established continue drilling to T. If however the gas flow increases and develops into major flow then the following procedures need to be followed. Once a major flow has been noted by the ROV maintain circulation through out the gas flow kill operation. Displace hole volume with 10 ppg kill mud.

If the gas stream does not diminish then pump 50 bbl barite plug at bottom. If the well is dead or subdued then proceed as with a minor gas flow, reaching to bottom TD in 3m interval prior to that ensure adequate kill mud is made available or once the well is under control then pump a cement plug above the barite pill and pull back to sea bed to review options.

If failed to subdue the gas flow with barite plug then prepare to pull rig off location. Moving Rig off Location The gas plume in shallow gas occurrences has been observed to form a low angle degree to the vertical. In m of water depth the gas plume will be approximately m wide. In such condition immediate action is to be taken to move the ship off the location by atleast m to be out of danger.

The ship will be moved upstream but not downward in order to move away from Shallow gas. In case enough room is not available we may have to go for emergency winching off with anchors. Jetting of 30" conductor Based on penetration test results tally is made such that top of PGB remain 1. Hold PGB with guidelines in place. Conductor pipes are run in the conventional manner through PGB with box down and pin up preferably with squnch joints for faster operation.

Lower all the conductor pipes. Jetting assembly length should be so adjusted that bit remains about 1 to 2 ft inside the casing shoe. Make up 30" running tool to the housing. Adjust space out to avoid first connection above seabed. Break circulation with seawater and ensure conductor is vertical using bulls eye of PGB. Jet in conductor following the parameters used for penetration test.

Jet down and position PGB about 1. Inclination of the conductor should not exceed one degree at any position. In between flush the hole using high viscous gel. Once required depth is reached remove all cuttings using high viscous pill.

Ensure inclination is within 1. Release casing running tool under surveillance by ROV. Record the distance between rotary table and the top of PGB at corrected tide for further reference. Mark guidelines at moon pool for reference. Eye pad may be welded to rest on rotary. Establish guidelines. Space out jetting assembly so that it will remain inside conductor casing. Make up TGB running tool to the jetting assembly. Lower the same and J on to the TGB.

Gently touch bottom and jet down to the point of refusal. Check the inclinometer reading. It should be within 1. Put paint mark on guidelines at moon pool level. Regulate guideline tensioners to lbs. Center the string among guidelines using chain pieces and nylon rope. Alternatively use guidance equipment.

RIH to bottom and drill down to T. Make wiper trip. Lower 30" casing through PGB and center with nylon rope and chain on guidelines. Fill casing, in case ball is used. Install 30" housing with its running tool. Break out Running Tool and run drill pipe as stingers using c plate. Lower and attach the housing to the PGB. Run the guidelines into guideposts and close the guidepost tops.

Install slope indicator on PGB and drill pipe. Tension guidelines to lbs. Lower the string until the PGB is one or two meters under water. When the casing is full replace bull plugs. Carry out circulation and cementation. Monitor returns during cementation. Check returns after WOC. Circulate thoroughly near housing before POOH. POOH completely without rotary and recover slope indicator. There are cases where even BOP gets lost in the seabed because of this.

In such cases cement should be pumped in large quantity in the annulus to avoid complications. Use compensator to avoid damage to PGB.

Also use ROV for monitoring. RIH to casing shoe. Drill down to 20" casing depth with seawater. In between remove cuttings using high viscous gel. Perform wiper trip after drilling to sectional T. Also drilling rate should not be very high as due to excessive cuttings in the annulus it caninduce fracture. Further ROV should be deployed at seabed for monitoring any gas coming from the well and around 30" casing.

Lowering 20" casing and cementation Casing is run in conventional manner. Set guideline tension to lbs. Fill the casing at regular intervals. Make up 18 well head and set in the rotary Make up and lower required length of stringer using 5" drill pipes using Sub Sea cementing manifold.

Make up running tool with wellhead. Monitor the approach of 18 well head towards 30" housing using ROV. Make up cementing head to last 5" drill pipe and connect cementing hose. Adjust the heave compensator to the weight of the landing string.

Land the 18 well head on the housing. Perform pick up test using compensator. Circulate thoroughly and carry out cementation.

After displacement with seawater, check water tightness at shoe. If NRV is used then plug can be bumped to ensure displacement. Check for back flow. Since formation at shallow depth is quite weak cement slurry should not be very heavy as it may induce fracture and due consideration should be given for low seabed temperature while designing cement slurry.

The BOP stack must be in perfect working order when lowered. Install guide lines in guide posts. Connect the riser, hanging from the hook to the BOP. Mount the riser angle beacon above the flex joint. Check all functions are in block position. Switch hydraulic power unit to block position.

Disconnect junction boxes on hose reels. Increase guideline tension to lbs. Check that tensioners bottle press is at calculated value. Stand by bottles to be at max press. Hoist BOP stack assembly with the traveling block. ONGC operates some drilling and 74 work over rigs. It is among the few companies in the world to have drilled deepwater wells in diverse and challenging areas, establishing itself as one of the leading oil drilling companies in India.

In order to have a more focused approach towards onshore, offshore shallow waters and offshore deep waters operations a new concept 'Company within Company' has been rolled out to bring about operational efficiency in offshore drilling operations. An in-house innovative PLC controlled Safety System for Travelling block movement has been successfully installed on an on-shore drilling rig.

Radial drilling, a productivity improving drilling technology, has been carried out in four wells for the first time to enhance reach in the reservoir and increasing flow path. Hydro fracturing technology has been playing crucial role in enhancing productivity of the wells all around the world. Procedure SOP for restoration of abandoned drill sites keeping in view the constraints being faced for restoration Table of Contents.

September ix. Million Metric Tonne. Mobile Offshore Drilling Units. Melting Point. Ministry of Petroleum and Natural Gas. Material recovery facilities. May 18, From: M. Haragopal, Chief Basin by llllls Oil and Natural Gas Corporation One set of environmental manual shall be made available at the drilling site! North East - Agartala Campaign. Presenting Author's e- mail Dec 6, Gold sponsors.

Institute, Washington. The period from to has been covered in the report. ONGC has in-house capability in entire facets of upstream Oil. Seismic data Acquisition, Processing. Reservoir Management. During the period of audit As per these new company. Atwood Oceanics. Diamond Offshore.

Global SantaFe. Japan Drilling Company.