Presentation on theme: "Packer Testing Program Design and Management"— Presentation transcript:
1Packer Testing Program Design and Management Eric E. Swanson, P.G., AquaLithos Consulting Brian C. Titone, P.G., Orogen HydroGeo LLC.Thanks for the introduction. Brian and I are going to tag team this talk.
2First of all I would like to thank everybody for being here, on the last talk of the day. The purpose of this talk is essentially a introduction to packer testing – Brian and I are both independent packer testers and we would like to share some of our thoughts on the various options to consider when launching into this type of an investigation.We’ll also share some thoughts on how to manage these type of activities and it should be relevant to both mining managers and consultants. We’re intentionally not going to get very technical, as our goal is to introduce this methodology to those of you that haven’t dealt with it before.What is Packer Testing?
3Packer Testing Overview What is a Packer? What is Packer Testing?An inflatable device that isolates a segment of borehole“Packer Testing” refers to hydraulic tests facilitated by the use of a packer to determine hydraulic conductivityWireline hydraulic packers are optimized for deep testing in conjunction with diamond core drillingSo, what is a packer and what is packer testing? A packer is simply a downhole device that is used to block off a section of a borehole and a packer test is simply a hydraulic test that is performed in this blocked off interval for the purpose of determining hydraulic conductivity.There are many different types of packers that are used for many different types of purposes, but this talk is focused on what we call “Wireline Hydraulic Packers”, which are very relevant to mining applications.
4Hydraulic Wireline Packers Designed for core rigsWater inflated, no high pressure gasRapidly deployed just like a core inner tubeRetrieved via rig wirelineNo cumbersome inflation linesOptimized for deep testing (100m-1000m)No need to trip out drill rods (saves time)What is a Wireline Hydraulic Packer? It’s a packer system that is designed specifically for use with diamond core drilling operations. There are new types of packers out that are applicable for use with RC and other types of drilling, but we are going focus on the Wireline Hydraulic Packer system here as it currently heavily used.These packers differ from other packers as they are inflated with water, using the core rigs pump system, are rapidly retrieved using the rigs wireline system. You don’t have to trip rods in or out and there are no inflation lines or support cables. This means that the system is quick to use and minimizes rig standby time. The system we are talking about has a optimal depth range of about 100 to 1000m, which is the sweet spot for many mining groundwater studies.
5Why Packer Testing?So you’re probably wondering why this is important to mining activities. Why packer test? Well, packer testing is really the best way to determine “discrete zone” permeabilities with depth. Why is that important? Here’s an example of a large open pit operation with some design and planning issues – notice the two failure zones on this pit wall. The failures here are the result of ignoring hydraulic pore pressures in the pit shell wall material and the rate at which these pressures would die off after mining starts. The pit shell design was done using traditional methods that did not include a hydrogeological component and it is costing the pit owner a considerable amount of consternation.
6Why Packer Testing?Hydraulic Wireline Packer Testing is the most economical way to collect “discrete” rock hydraulic conductivity data at depths relevant to most mining operations.In most fractured hard rock mining environments,hydraulic conductivity can be a function of depth and fracture frequency, not always rock typeDecreasing Hydraulic ConductivityThis hydraulic conductivity / depth curve is critical for the development of accurate ground water models and geotechnical designHere’s some data from another project in the planning stages where hydraulic conductivity was determined using the packer. What packer testing did for this project was to generate a series of conductivity decay curves with depth, which in turn provided data both the pit shell geotechnical modeling and an overall groundwater model. It also assisted with dewatering planning.This graph, which might not be too readable for those of you in the back shows a series of packer test results that define the changes in hydraulic conductivity with depth. Obviously permeability decreases with depth, but what is important is the way it changes with depth and as a function of other data such as fracture frequency. Surprisingly, at many sites in hard rock settings common to mining, the hydraulic conductivity is not a function of rock type, but a function of fracture frequency, which is in turn a function of depth.Hopefully I’m showing you why packer testing is important and how it is currently being used in the industry.This type of data is critical for a reliable pit shell design, critical for an accurate groundwater model, and critical for dewatering planning. If you’re building a groundwater model without an idea of how permeability changes with depth, your not necessarily building a reliable one.
7Packer Testing Strategies Decisions, Decisions….Packer Testing Planning MatrixDevelopment StagePreliminary DrillingPre Feas. / FeasibilityExpansion / InfillProgram ScaleMultiple drill rigsSingle drill rigMultiple PackersTest TypeInjection TestAirlift TestFalling HeadShut-in TestsTest PurposePit Design (Geotech)Dewatering PlanGroundwater ModelTesting FrequencyEntire boreholeSelected IntervalsOpportunisticWhen to TestConcurrent with drillingCompletion of boreholeSo now that I’ve sold you on the concept of why you should packer test, let me talk about what to consider, and the various decisions that need to be addressed while planning and performing a packer testing campaign. Here we have a rough, and not necessarily inclusive matrix of all the decisions and options associated with designing a packer testing program. The topics to the left are more strategic in focus and need to be decided up front, while the topics over to the right are more tactical in focus and can be decided in the field as conditions occur.The first decision topic is “At What Development Stage is Packer Testing Applicable?” The answer depends on your project – when do you need an accurate pit shell design, when do you need to develop an accurate groundwater model and when do you need to start thinking about dewatering. The other answer is operational: As packer testing goes hand in hand with core drilling, any time you have core rigs on site is when you should be thinking about packer testing.The second topic is “What is the purpose of this testing?” Is it related to a geotechnical pit shell or underground design? Is it associated with an advanced dewatering plan? Is it a source of data for a permitting related groundwater model?Who is going to do this type of work? Can you hire a big box consulting firm to do it? Can you train internal department staff to do it? Can you rely on specially trained drillers to collect this data?Now lets talk about some of the operational issues in planning a packer testing program. As I’ve said, packer testing goes hand in hand with core drilling. How many drill rigs will you be packer testing with?.Should you be testing the entire borehole or is it o.k. to just test on selected intervals or intervals of interest (like across a fault zone)?Wireline hydraulic packers can be operated in two configurations – single packers and double packers. Which one is right for the job at hand?Test types - The most common type of test is a step injection test, but this type of testing is not accurate at higher permeabilities. You might want to have the capabilities to perform an airlift test if you anticipate higher permeability.Should testing be performed concurrent with drilling or at borehole completion?Finally, will testing be performed on discrete zones or consist of what is called a cumulative test, which Brian will talk about later.Staffing PlanConsultantsInternal StaffDrillersTest ConfigurationSingle PackerDouble PackerAnalysis TypeDiscrete zone testCumulative Analysis
8Types of Packer TestsI’m going to hand this off to Brian now – he’s going to talk about the specifics of some of these approaches and has developed some snazzy animations that describe them in detail. Brian……
9Packer Test Basics Drill Rod Landing Ring (seal) Core Barrel Water FilledFracturesDrill BitPackerTest IntervalBottom of OpenBorehole
10Single Packer TestSingle element packer test interval are bound by the base of the packer and the bottom of the boreholePressurized Water from rig pumpWater enters hole through packer into formationWater filledfracturesBase of Drilled Interval
11Double (Straddle) Packer A straddle packer allows zones to be tested discretelyTypically done during Cumulative TestingTest zones can be 1m or larger.Upper PackerTest ZoneLower Packer
12Injection (Lugeon) Testing Injection testing involves injecting water at specified pressures and recording flowStepPressureFlow Rate120 psi4.2 L/min240 psi7.5 L/min360 psi12.1 L/min47.3 L/min54.1 L/minExample data
13Airlift TestingAirlift testing involves removal of water using compressed air. Constant flow is measured, then air is turned off and water is allowed to recover. Hydraulic conductivity is determined using rising head analysis.Air lifted water and airWater enters from the formationPressureTime
14Falling Head TestFalling water columnFalling head tests can be conducted by rapidly filling the rods with water and allowing it to drain into the formation. The resultant curve can be analyzed for hydraulic conductivity. This is typically done after an injection test for quality assurance.Water enters the formationHeight of WaterPressure transducer measures water levelTime
15Concurrent or Completion Testing? Concurrent testing occurs during drillingCompletion testing is performed after drilling is finishedConcurrent TestingCompletion TestingAdvantages:Higher quality dataNo hydraulic conductivity maskingHole stability less of an issueDisadvantages:Takes longerRequires crew and packer during drilling (higher cost)Advantages:Rapid testing (more tests in shorter time)Less rig standby timeTesting crew required only at hole completionDisadvantages:Hydraulic conductivity “Masking”May require straddle packer to resolve any hydraulic conductivity maskingLower quality dataConcurrent testing is preferred, Completion testing used for special situations
16Discrete Test Measured Values Cumulative TestingThe entire hole is drilled then packer testing is performed in intervals on the way out. Measured values in upper zones may be masked by high hydraulic conductivity in lower zones.K=2.6e-4m/dayK=2.3e-4m/dayDiscrete Test Measured ValuesIntervalK (m/d)50-100m8.0e-5m1.0e-5m2.3e-4m5.0e-6K=2.3e-4m/dayK=5e-6m/day
17Packer Testing Program Design Test Program ObjectivesScoping and ScalingLogistics and EquipmentBudgeting and Cost ControlsScheduling and CoordinationStaffing OptionsThanks Brian.O.K. Now that you’ve seen some of the ways the packer can be used, lets talk about some program design considerations
18Defining Test Program Objectives Clearly defined end uses of packer testing data leads to an efficient field program that is neither to large or too small in scopePlacing a little more effort on clearly defining and communicating data objectives is money and time well spentIt is critical that the end users of packer testing data be involved in the field planning, i.e. groundwater modelers and geotech engineersTesting program objectives need to be designed around the end uses of the data (geotechnical, permitting, hydrogeological, dewatering, etc). You don’t want to design a program that is too big or not big enough to meet your data needsClearly defining and communicating your test program objectives is time well spent. Unfortunately many of us fail to do this.You should always involve the end users of the data in the field planning activities. This data is for them, and they need to drive the decision related to how much, where, and what type of data is needed.
19Scoping and ScalingMultiple Drill Rigs, Multiple Packer Systems, Multiple Test CrewsMultiple drill rig advantagesMaximizes efficiency of testing crew and equipmentMultiple packer system advantagesConcurrent testing on multiple rigsReduces risk due to equipment loss or damageReduces transportation time between rigsAdditional testing personnel advantagesAllows for sustainable day/night operationsContinuity during shift rotationsCollaborative problem solvingEliminates excessive standby when using multiple rigsOnce you have a good idea of your project objectives, you can start thinking about the scale and scope of your packer testing program. Your project goals and budget should drive the number of involved rigs, packer kits and field crew size. Finding the best combination of these elements requires experience.Redundancy is a good thing. Having multiple packer systems available reduces operational headaches, especially in difficult access environments. It also prevents disaster in the case of equipment loss or damage as one packer system can be cannibalized to support the other. Large or intensely scoped projects might require multiple packer systems for tests on multiple rigs.The bottom line here is that redundancy reduces program risk, but increases costs. The other bottom line is that there is an efficiency of scale at play here. Sometimes short duration, high intensity programs are more cost effective than low intensity, long duration ones.Bottom line: Redundancy reduces risk but increases costs
20Logistics and Equipment "Amateurs talk about tactics, but professionals study logistics.“ - Gen. Robert H. Barrow, USMCComplete equipment listTiming of personnelCustoms delaysAccess of materials in remote sitesAvailability of materials locallyPacker testing is an equipment intensive activity, and a overlooked piece of the testing gear can bring the whole program to a halt. It is important to focus on your equipment lists prior to mobilization, and think through each step of the plan and each step of the back-up plan to ensure that you have what you need to get the job done. I’ve seen a lot of costly delays happen due to a simple oversight in equipment loadouts.Having worked in remote areas and third world countries, I would stress the importance of realistic estimates for the logistical delays associated with customs clearance. Paying a consultant standby time for a week while waiting for their packer gear to clear customs can really impact a budget. In third world settings it is important not to mobilize your packer testing staff to site until the equipment is procured and is physically at the mine.
21Budgeting and Cost Control Packer testing can be expensive, but there’s no reason to take a bathCareful planning and an experienced project team is the key to cost controlAdding packer testing to an existing drilling program saves moneyThe highest cost component is consulting fees. Training junior staff on the packer equipment can reduce costs.So we are in a mining down turn – everybody is thinking about how to cut costs and do more with less. I’m sure all of you have felt the pain.I want to share some ideas here on how to shave costs on a packer testing program. The first thing to recognize, and point I’ve been trying to hit home is that real cost savings start with careful planning – involve an experience person on the planning side of the equation. Consulting firms that haven’t attempted Wireline Hydraulic Packer testing should look for a sub-consultant to do this work, or a trainer to bring their staff up to speed.Packer testing is most cost effective when combined with another drilling objective, or as an “overlay” on existing drilling plans. If you are planning to core drill, don’t overlook adding packer testing to it.The highest costs associate with packer testing are associated with labor. Training low cost junior staff on the packer can off-set the costs associated with high dollar specialist consultants.The biggest wastes of time and money I’ve seen on packer testing projects involve simple equipment errors and logistical delays. Again, planning and double checking is the key to avoiding this embarrassment.A significant and avoidable cost on many projects is standby time due to logistical delays, scheduling, and equipment issues
22Scheduling and Coordination Drilling rate and subsurface conditions make packer testing scheduling highly uncertainDuring single rig packer testing, much of the testing crew is on standby, waiting for the borehole to advanceDue to the 24/7 nature of drilling, testing may take place during day or night shift and is highly irregularScheduling and coordination of a packer testing campaign can be a real headache. This is primarily due to the uncertainties of drilling operations associated with unknown subsurface conditions, unanticipated access issues, and drill rate uncertainties. Rigid schedules are rarely adhered to.The best way to handle scheduling issues is to give the field team autonomy to test when appropriate and when available. Field team autonomy has certain drawbacks, especially if the field team is not up to speed on the overall project objectives – critical zones get missed, irrelevant data gets collected, etc.In my experience, it’s best if the project manager is also the field team leader, or is forward staged in the field with the packer testing crew. Although it adds some expense to have a high dollar person on the ground, that expense is recouped by maximizing efficiency and shortening the chain of command.As we have seen there are many ways to perform a packer test, many ways to get at the required data, and many ways to screw it all up. Take my advice and don’t attempt to manage a packer testing program from the office.Flexibility in testing methods and test interval selection can mitigate irregularities and promote efficiency
23Staffing OptionsSuccessful Packer Testing Requires a Trained and Motivated StaffThe staffing mix is a balance between cost control and testing effectivenessStaffing Options Include:Specialized Consulting FirmsMining Project Internal StaffSelf Performing DrillersIndependent Experts / TrainersFinally, I want to talk about staffing issues. Who is going to perform the testing?The key to a successful packer testing project is having experienced staff. This can be a large consulting firm, internal mining project staff, drillers or an independent expert. And the decision is always a trade off between cost control and testing effectiveness.For short duration projects, its usually better to hire experienced consultants that have done this before and can hit the ground running with minimal delays. This is expensive, but cost effective on short term projects. On longer term projects, it may be more cost-effective to train internal mining project staff to do the work with an experienced advisor present to trouble shoot and double check results.Staffing Considerations:Day and Night Shift OperationsScale and Scope of Testing ActivitiesProgram Duration and Mobilization Costs
24ConclusionsReliability in mine design requires the right types of dataFor deeper mine designs, this means discrete zone hydraulic conductivity dataHydraulic wireline packer testing is the best way to acquire this dataMany different options can be used to obtain your data objectives and control costsThe key is careful program planning, using experienced consultants, and keeping the big picture in in mindMy concluding remarks are simple:Reliable mine design, dewatering planning, and groundwater modeling requires the right type of dataFor modern deep mine designs, this means discrete depth zone hydraulic conductivity dataHydraulic wireline packers are optimized to collect this type of dataThere are many different options and strategies that can be used to increase data quality and decrease costsAnd that the key to a successful packer testing campaign is careful up-front planning, using experienced testing personel or trainers, and keeping the big picture in mind
25Thank you for attending Thanks to Inflatable Packers International (IPI, Perth, Australia)Brent Johnson (Interralogic, Golden, CO)Thanks everybody for staying for our talk. Thanks to Brent Johnson at InterraLogic and IPI packers for all of their assistance. See you all at the banquet tonight.