lesson 16 risk management and problems

8/12/2019 Lesson 16 Risk Management and Problems

1/89


2/89

Harold Vance Department of Petroleum Engineering

Risk Management and

Downhole Problems

Risk ManagementRisk Identification

Quantitative Risk Analysis

Risk Mitigation Planning


3/89


Downhole Problems andTroubleshooting

Wellbore Instability

Excessive Vibration

Fluid Influxes

Stuck Pipe and Fishing

Corrosion

Risk Management and

Downhole Problems


4/89


Risk Management

A major success factor in UBD ishow effectively the designers andimplementers identify risks and

develop an effective plan to dealwith the risks.

Introduction


5/89


Risk Management

Before implementing the finaldesign, the selected equipmentand operating procedures should

be subjected to an exacting riskanalysis.

Introduction


6/89


Risk IdentificationQuantitative Risk Analysis

Risk Mitigation PlanningRisk Response

Risk Management

Stages


7/89




Risk Management


8/89


Source of Risk.

Probability of Occurrence.Potential Impact.

Action to Mitigate.

Cost to Mitigate.

Probability Mitigation Succeeds.

Risk Identification


9/89


10/89


Probability of Occurrence

Can be on a scale of:1 to 10 or

High, Medium, and Low


11/89


Potential Impact

High, Medium, or Low.

May be referred to asConsequenceCan be defined by dollar amounts or

other criteria, such as severity ofinjuries or death, or any combination

of dollar amount and injury.Probability * Consequence = Risk


12/89


Action to Mitigate

Next, the decision whether to live

with the risk or if risk mitigation isin order.

Mitigation involves reducing the

probability of occurrence or thepotential impact of a given risk.


13/89


Risks can be mitigated by:

Choose substitute equipment types.

Upgrade specifications such as

materials strength, ratings, etc.Modify the basic design.

Transpose steps in the procedure.

Change mud systems, completionoptions, etc.

Include backup equipment.


14/89


Cost to Mitigate

The relative cost to mitigatemust be estimated, based onrough approximations, in order

to evaluate the viability of themitigation actions.


15/89


Probability MitigationSucceeds

Estimate the probabilitywill succeed.


16/89


Risk Mitigation Table

Description of

Risk

Sourceof Risk

Probabilityof

occurrence

PotentialImpact

Action tomitigate

Cost toMitigate

ProbabilityMitigationSucceeds

Hurricane strikeswhile drilling andrequires shut downof operations

E Low Medium

Create plan fortemporary shut-inof well andabandonment ofoffshore platform.

Low High

Drill string failure I Medium Medium

Institute tubulartesting programthat includespressure testing

and magneticscanning of micro-fractures

Medium High


17/89




Risk Management


18/89


Quantitative Risk Analysis

What is Uncertainty?

Risk Analysis and Decision-Making.What is Quantitative Risk Analysis?

When should I use Quantitative

Risk Analysis?Why should I use Quantitative riskAnalysis?


19/89


What is Uncertainty?

Dictionary definition:

the estimated amount orpercentage by which an observed orcalculated value may differ from thetrue value

Benjamin Franklin pointed out:

In this world nothing can be said tobe certain, except death and taxes


20/89


Risk Analysisand Decision-Making

Risk analysis and decision making arefundamentally related.

A key component of Risk Analysis isto provide support for a particulardecision.

In our industry, the decision that

requires risk analysis is usuallysubject to acceptance by a team oftechnical professionals and approvalby management.


21/89


What isQuantitative Risk Analysis?

Any technique for analyzinguncertainty and quantifying theeffects of that uncertainty on

factors that will significantlyeffect decision making.


22/89


A method of quantifying the consequencesof the risks identified by intuition through a

structured approach to decision makingbased on:

what you think you know and dont

know.What you can do.

What you want the outcome to be.

What isQuantitative Risk Analysis?


23/89


When should I useQuantitative Risk Analysis?

Risk analysis can be usedthroughout an UB project toimprove the quality of technical

evaluations and improve riskmitigation techniques.


24/89


25/89


Probabilistic methods providebetter decisions than deterministicmethods because a full range ofpotential outcomes is examined.

Why should I useQuantitative Risk Analysis?


26/89


Quantitative Risk

AnalysisThe Process

Problem Identification.

Deterministic Analysis.

Probabilistic Analysis.

Evaluation andCommunication.

Decision and Action.


27/89


Problem Identification

Identify the problem, the reason

that a solution is required, andproject desires.

Collect and review data.

Verify accuracy of data, and ensureit is pertinent to the issue at hand.


28/89


Deterministic Analysis

Construct a model relating inputs

and possible outcomes.Perform a sensitivity analysis and

present the results in graphs and

tables.Identify key variables and examine

them in more detail.


29/89


Probabilistic Analysis

Assign key variables a range andprobability distribution.

Conduct an assessment using

Monte Carlo simulation.


30/89


Evaluation andCommunication

Check if the results make sense,determine if additional informationis needed, and create graphs andtables to communicate the results of

the analysis.


31/89


Decision and Action

Recommend the best alternativeconsistent with the analysis andproject desires.


32/89


How to do a HAZOP

HAZOP


33/89


Essential Elements

Procedure/System Layout.

HAZOP Form.

Small Group.

Recorder.Co-ordinator.


34/89


Conventional MudLift with SAC and DSV (SS Pump on Inlet Pressure)

Shut In-Drlg

1. Raise kelly/top drive until the drivebushing clears the rotary.

2. Stop pumps and check for flow.3. Open choke line fail safe valve (with

choke closed).

4. Close upper annular. (Someoperators may prefer to shut-in on

rams instead)

5. Check for leaks, notify supervisor,record SIDPP, SICP, Pit Gain, Time,

Date.6. Close upper pipe rams. (Depending

upon the stack, could be middle rams)7. Reduce closing pressure on upperannular, and lower drillstring untiltool joint rests on closed upper pipe

ram.8. Open upper annular and restore

closing pressure to normal.9. Prepare for kill.

1. Raise kelly/top drive until the drive bushing clears the rotary.2. Isolate SAC from wellbore.3. Stop rig pumps (DP pressure falls to DSV opening pressure); SS pump maintains

seawater hydro. If SS pump keeps running, well flow is verified.4. Stop subsea pump. Record SS inlet pressure (excess above sea hydro is SICP.)

Pump slowly on DP until pressure flattens (DSV opens). SIDP is increase above

pre-recorded DSV opening pressure.

5. Close upper annular. (Some operators may prefer to shut-in on rams instead)6. Check for leaks, notify supervisor, record SIDPP, SICP, Pit Gain, Time, Date.7. Close upper pipe rams. (Depending upon the stack, could be middle rams)8. Reduce closing pressure on upper annular, and lower drillstring until tool joint

rests on closed upper pipe ram.

9.

Open upper annular and restore closing pressure to normal.10.Prepare for kill.Discussion:

The use of the DSV will allow faster shut in and flow measurements. Closure of the DSV after mud circulation is stopped will make measurement of SIDPP

more complicated.

There must be a means of isolating the SAC from the wellbore pressures upon shut-in. Isolation of SAC will slightly complicate the shut-in procedure relative to

conventional riser drilling.

Procedure


35/89


36/89


System Layout


37/89


Date: ______________

HAZOP(RISK ASSESSMENT)

WC-1_

MUDLIFT MODE: WC-1 Drilling with SAC and DSV with Shut-In (Base Case) Page: ofACTIVITY: Kick Detection, Stop Flow/Shut-In, Measurement, Drillers Method

REASON: Probably preferred MODE and procedures for most participants

ASSUMPTIONS: Hangoff @ SI; SS Pump on Inlet Pressure = Sea Hydro Before Kick; DSV set for Positive Opening Pressure

Probability (H,M,L) RISKHazard Consequence (H,M,L) Existing Safeguards

Avg C x P

Shut-In, Pit Gain,

SIDP, KCP, DP Sch.

Description

1.2.3.4.5.6.7.8.9.10.11.12.Put Participants names in shaded boxes for individual assessment of Probability. Put weighted Average in Avgcolumn.

HAZOP Form


38/89


Small Group

Large groups unwieldy.

4 to 8 about right.

All should take active part.


39/89


Recorder

Act as Wordsmith.

Good with a Laptop.

LCD Projector handy.


40/89


Co-ordinator

Familiar with HAZOP process.

Monitors discussion.

Keeps focus.

Dampens noise level.Helps Recorder.


41/89


What-If for Hazards

Unobserved Event.

Equipment Failure.

Unworkable Procedure.

Unrealized Expectation.


42/89


With a Hazard Named:

Figure Out Consequences.

Decide Probability.

Calculate Risk.

Stick to Agreed Definitions.


43/89


Consequence Effect

HIGH

Fatality

Or

Damage $ 1-10 MM

MEDIUM

LTI-Disability

Or

Damage $ 25K-1 MM

LOW

Non-LTI Injury

Or

Damage < $ 25K

NOTE: These are possible consequences of hazards that can develop even with existing Safeguards inPlace prior to modifications resulting from the HAZOP.

Qualify Consequence


44/89


45/89


RISK MATRIX

PROBABILITY

LOW MEDIUM HIGH

CONSEQUENCE

HIGH H*L = M H*M = M H*H = H

MEDIUM M*L = L M*M = M M*H = M

LOW L*L = L L*M = L L*H = L

For Well Control, Risk must be at Low Level.

Risk = Consequence*Probability

Risk


46/89


With Risks Assessed

Fill Out the Form.Final Entries inRiskColumn.

OnlyLowRisks Acceptable.


47/89


Now What?

Here

Wrap it up!!Real World

Three more steps.


48/89


Final Steps

MitigationRevised Risk

Proposed Action


49/89


Slow process.

Both constructive & destructive.

Side issues can mess it up.

Probably not right the first time.Consequence vs. Catastrophe.

Perils & Pitfalls


50/89


Problem withQuantitative Risk Analysis

Determining the probabilities.

Mis-understanding of the innerworkings of the model.

Lack of reality checks.

Ignoring relationships betweenvariables.

Use of subjective judgments.


51/89




Risk Management


52/89



Risk Mitigation Plan

Risk Response


53/89



Should be incorporated into theindividual well program for each well.

Should include a brief description ofthe operations risks identified andanalyzed in the previous phases and

suggested mitigation measures thatwere derived.

Keep is simple.


54/89


The plan should include:

Emergency phone numbers.

Engineering drawings andsketches.

Risk mitigation procedures.



55/89


Risk Response

Field personnel must be ready toimplement emergency responses.

Inspections, audits and field visitswill assist in ascertaining theability of operations personnel torespond to a particular risk.


56/89




Excessive VibrationFluid Influxes

Stuck Pipe and FishingCorrosion


57/89



Causes of Instability

Symptoms

Prevention

Solutions and Treatments


58/89



Mechanical - Most are related to mudweight, more specifically, to mud

weight reduction while attempting toget underbalanced.

Abnormal pressure, tectonic stress,

and unconsolidated formations areall causes of mechanical wellboreinstability.


59/89


Chemical - related to reactivityof shale and/or clay that may bepresent in other formations.

Most causes by exposure to freshwater.



60/89


Symptoms

Most symptoms are due to rock failureand excessive amounts of formation in

the wellbore. Include:

increased torque/drag.

increase fill on bottom duringconnections/trips.

increased annular pressure.

excessive cuttings at the surface.


61/89


Prevention

Determine the cause.Adequate mud density.

Proper chemical make-up of

the drilling fluid.


62/89


Solutions and Treatments

Increase circulation rate.

Keep pipe moving at all times.

Use inhibitive fluids.

h l bl d


63/89






Corrosion


64/89


Excessive Vibration

Causes of Excess Vibration.

Symptoms of Vibration.

Prevention and Solution to

Excessive Vibration.

C f E


65/89


Causes of ExcessVibration

Drilling rough, highly fractured orabrasive rocks.

Hard rocks.

Improper handling of percussiontools.

Gas drilling does not dampenvibrations as much as liquids.


66/89


Symptoms of Vibration

Drillstring damage noticed throughinspection.

High incidence of downhole toolfailure.


67/89


Prevention and Solution to

Excessive VibrationKeep the drillpipe in tension.

All compressive forces should becontained in the BHA.

Calculate the neutral point so thatwhen the maximum WOB isapplied, the neutral point is in theBHA.

D h l P bl d


68/89







69/89


Fluid Influxes

Causes

Symptoms of Unwanted Influxes

Prevention of Influxes

Solutions to Unwanted Influxes


70/89


Causes

Major cause is UBD.

Three requirements for influx.some measurable porosity.

Permeability.

wellbore pressure < formationpressure.

Symptoms of


71/89


Symptoms ofUnwanted Influxes

Fluids being returned to the surface thatare not pumped into the wellbore.

Damp cuttings when drilling with drygas.

Reduction in the number of cuttings at

the surface. Increased injection pressure.

Loss of returns.


72/89


Prevention of Influxes

Only real prevention is to drill

overbalanced.

But this is not possible if ourgoal is to purposefully drillunderbalanced.

Solutions to


73/89


Solutions toUnwanted Influxes

Control influx rate.

When drilling with gas or air,

attempt to unload the liquids fromthe hole. May require a switch tomist drilling.

Increase EMW in stages.

Carefully weighting up the system.

Do hole P oble d


74/89





Corrosion



75/89



Causes

Symptoms

Prevention

Solutions


76/89


Causes

All causes of stuck pipe can

occur during UBD exceptdifferential sticking.

Keyseating.

Excessive cuttings due towellbore instability.

Mud rings.


77/89


Symptoms

Cannot pick up the drillstring.


78/89


Prevention

Proper design of thedrillstring.

Adequate hole cleaning.


79/89


Solutions

Fishing.

Downhole Problems and


80/89







81/89


Corrosion

Requirements for Corrosion.

Causes and Factors EffectingCorrosion.Symptoms.Prevention.Solution.

Requirements for


82/89


Requirements forCorrosion

Requires the presence of four

components:an anode (component that corrodes).

a cathode.

an electrolyte.an external connection.


83/89


Simple Corrosion Cell

Causes and Factors


84/89


Causes and FactorsEffecting Corrosion

Fluid utilized is the single largestsource of corrosion. The fluidbecomes the electrolyte.


85/89


Corrosion Rate Factors

Oil content.

Conductivity of electrolyte.

pH of the fluid. Temperature and Pressure.

Fluid velocity.

Bacteria.

Internal and External stressconcentrations.

Presence of dissimilar metals.


86/89


Symptoms

Generalized corrosion.Pitting.


87/89


Prevention

Corrosion cannot be stopped,but it can be slowed.


88/89


Solution

Avoidance

Inhibition


89/89

END

lesson 16 risk management and problems

Documents