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University of SalfordManchesterMSc Petroleum & Gas Engineering

Geology, Exploration, Drilling and Production

Formation Damage PresentationLecture: Dr. G. C. EnyiMarch, 2015

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Describing its impact, Amaefule et al (1988) described it as an expensive headache to the oil and gas industry.Emphasizing the uncertainties involved; Bennion (1999) describes formation damage as the impairment of the invisible, by the inevitable and uncontrollable, resulting in an indeterminate reduction of the unquantifiable.According to Faruk, Formation damage is an undesirable operational and economic problem. This is an impact in the reduction of oil and gas production.Formation Damage can cause significant decreases in well productivity and worldwide yearly lost production due to Formation Damage is equivalent to billions of dollars in lost revenue.

FORMATION DAMAGEWhat is Formation Damage?

Solids pluggingClay particle swelling or dispersionSaturation changesWettability reversalEmulsion blockageAqueous-filtrate blockageMutual precipitation of soluble saltsFines migrationDeposition of paraffins or asphaltenesCondensate bankingBacterial plugging

MECHANISMS OF FORMATION DAMAGE

In petroleum reservoirs, some of the common mechanisms by which formation damage occurs are categorised as follows:Mechanically Induced, which are also drilling induced. These will include physical migration of In-situ fines, solids entrainment phenomena, etc.Chemically Induced, reactivity clay induced damage. An example is the common problem of high concentrations of asphaltenes when they are destabilized.Biologically Induced, where bacteria as a leading cause can be introduced into the formation during any of oil recovery operationsThermally Induced; mineral transformations, wettability alterations, mineral and formation dissolutionCATEGORISATION OF MECHANISMS

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Jaimes et al (2014) also described the mechanisms of formation damage as:Block in the face of the formation, produced by the tendency to form emulsions between the oil of the well and the completion brine Production of inorganic scale in the porous medium during the contact of the formation water with the completion brineblockage by suspended solids present in the completion brinesIncreased bacterial activity in the wellbore vicinityrock-fluid incompatibility due to sensitivity of the formation minerals to the completion brine, caused by high ion exchange, causing swelling of clays and reduction of the permeabilityincrease of the water relative permeabilityMECHANISMS

According to Yeager et al. (1997), downhole diagnostic tests that can be conducted in the field include:

Well-test analysis.Downhole video. Physical sampling in the form of downhole liquids and solids. In the open hole completions, rotary sidewall core samples.Evaluation of Formation Damage in the Field

Hitwell E-Cam

Perforations (Hitwell)Oil entry through perforations (Hitwell)Downhole Video

(Yeager et al., 1997) states that for open hole completed wells damage can be diagnosis primarily be obtaining a core samples from the well bore wall in the zone of interest and evaluating those samples to determine the formation damage

Rotary sidewall coring tool (after Yeager et al., 1997 SPE)Core Sample

A kind of temporary, partial completion of the well that provides data on several feet or several hundred feet of producing formation

The purpose of this test is to know:

1. Type of producing fluid (oil, gas)2. Initial reservoir pressure (pi)3. Effective permeability ( K)4. Skin Factor (s)5. Ability of the well to produce oil (Q)

Well Testing (DST)

CONCEPT OF SKINSkin is a factor that is used to measure the extent of damage or the decrease in formation permeability compared to the original permeability.It has no physical dimension.Skin can be zero (No effect), positive or negative.

SKIN ANALYSIS

For an undamaged formation: ..equation 1

SKIN FACTOR

For a damage formation:

..equation 2

PRESSURE PROFILE FOR AN IDEAL WELL IN NEAR WELL BORE REGION

Pressure drop across skin ..equation 3Combining equations 1 and 2: equation 4Skin .equation 5

Components of skin effects: .equation 6

PRESSURE PROFILE FOR A WELLBORE

Formation Damage Laboratory Studies

A study of Formation Damage at different drilling Environments

By Teow Ket Seang, Issham Ismail & Abdul Razak Ismail

Faculty of chemical 7 Natural Resources EngineeringUniversity Technology Malaysia

Aim: To study formation damage at different drilling environment

Data and Graph

Discussion of ResultResult shows that Drilling, Completion, Work over, Production and Simulation are potential source of Formation Damage.Others are long time contact time with drilling fluid; mud type; differential pressure (increases fluid loss damage the formation); annular velocity (120ft/min 150ft/min particles invade formation); drill pipe rotating speed and rock permeability. Temperature at 70oC = 158oF damage increases.

ConclusionsHorizontal drilling environment causes more severe formation damage than the deviated angle drilling.

Understanding the physical attributes that causes formation damage will help minimize it.

RecommendationsPolymer(a foaming agent that is used in the mixing of mud to achieve a desired purpose) should be used minimally to avoid thermal degradation.Temperature should be regulated not to exceed 158OF (70OC) to avoid drastic increase in damage.A higher annular velocity should be avoided.The differential pressure should be lowered not to reduce the rate of permeability.

Formation damage reduces the rate of flow of hydrocarbons into the wellbore, and thus into the production pipeline. By reducing formation damage, wells can flow at a higher rate, increasing the profitability of the well by moving up the peak production years which means faster pay-outs.

This can be achieved if you know how to avoid these fluid-related causes of formation damage:Foreign particle invasion and pluggingFormation clay dispersion and migrationChemically incompatible fluidsOil wetting of reservoir rockEmulsion and water blockingFluid invasion

Minimizing formation damage

Years of ProductionBarrels of Oil per Year

Reducing formation damage can help reservoirs to produce at higher rates, resulting in faster payouts for the operator

Causes of formation damage related to drill-in and completion fluids include (CLICK):Fine drilled solids and foreign particle invasion and plugging; Formation clay swelling, dispersion, migration, and blocking of the flow channels; Chemically incompatible fluids with natural reservoir fluids; Fluid invasion, and Emulsion and water blockingFormation damage reduces the rate of flow of hydrocarbons into the wellbore, and thus into the production pipeline. (CLICK) By reducing formation damage wells can flow at a higher rate, increasing the profitability of the well by moving up the peak production years.23

N-FLOW Delayed Action Filter Cake Breaker can effectively remove filter cake with an in-situ reaction, leading to reduced formation damage and increased production.Formation damageDecreased production and injection ratesIncreased costsIncreased rig timeChemical costs

Incomplete filter cake removal may result in:

BEFORE N-FLOWTMAFTER N-FLOWTMMinimizing formation damage

Video of Halliburtons Solution on completely removal of filter cakes

Situation: Reservoir section was drilled using Oil-based mud. Reported skin damage was up to 25-30.

Possible causes of reduced permeability: Pore size distribution test were not performed Strong emulsifiers were used in the oil based mud Poor well cleaning; Inefficient filter cake removalReservoir section was directly perforated with completion fluid without using additives to prevent structure blockingThe issues of YPERGAS Project

Design of drilling and completion fluids reduces formation damage in reservoir of gas wells; Venezuela basin, Yucal Placer Field Case Study

Situation: Halliburton designed a customized solution to maximize reservoir potential

The solution:Pore size distribution analysis to determine optimal size of bridging materials to enable reservoir protection while drillingDetermine the optimum design of the bridging package for effective sealing of the formationUse the Baroid System,100% oil based mud to avoid blockage due to emulsion within the fine porous structure of the reservoirControl of HP/HT filtrate to minimize invasion of fluid to the formationPerform effective cleaning of the wellbore using chemical train of pills using Completion Fluid Graphic software Perform fluid loss control to prevent the entry of water-based fluid during the perforating

Halliburtons SolutionThe customized fluid plan solution resulted in 30 % higher gas production per day from the well and a skin factor of 8. Economic Value created

Horizontal drilling environment causes more severe formation damage than the deviated angle drilling.Understanding the physical attributes that causes formation damage will help minimize it.Create maximum production and injection potential by effectively removing filter cakes with N-FLOWTM breakers.Recommendations & Conclusions

Jaimes, M., Castillo , R. D., Villar, A., Escobar, M., Dorado, R. & Acevedo, N., 2014. Integrated Analysis To Identify and Prevent Formation Damage Caused by Completion Brines: A Colombian Field Application. Venezuela, Society of Petroleum EngineersRenpu, W. 2011. Advanced Well Completion Engineering. Petroleum Industry PressCivan, F., 2007. Reservoir Formation Damage (Fundamentals, Modeling, Assessment and Mitigation) 2nd Edition.D.B. Bennion, F.B. Thomas, D.W. Bennion and R.F. Bietz Hycal, 1995. Mechanisms of Formation Damage and Permeability Impairment Associated With the Drilling, Completion and Production of Low API Gravity Oil Reservoirs. Energy Research Laboratories LtdFormation damage.(2015).Petrowiki. Retrieved 13th April 2015, from http://petrowiki.org/formation_damage

James A. C.(2014). Skin effects. Retrieved 13th April 2015 from http://www.slideshare.net/akincraig/2-skin-effectsHalliburton. (2012). Design of drilling and completion fluids reduces formation damage. Retrieved March 27, 2015, from http://www.halliburton.com/: http://www.halliburton.com/public/bar/contents/Case_Histories/web/H09319.pdfJaimes, M., Castillo , R. D., Villar, A., Escobar, M., Dorado, R. & Acevedo, N., 2014. Integrated Analysis To Identify and Prevent Formation Damage Caused by Completion Brines: A Colombian Field Application. Venezuela, Society of Petroleum EngineersRenpu, W. 2011. Advanced Well Completion Engineering. Petroleum Industry PressCivan, F., 2007. Reservoir Formation Damage (Fundamentals, Modeling, Assessment and Mitigation) 2nd Edition.D.B. Bennion, F.B. Thomas, D.W. Bennion and R.F. Bietz Hycal, 1995. Mechanisms of Formation Damage and Permeability Impairment Associated With the Drilling, Completion and Production of Low API Gravity Oil Reservoirs. Energy Research Laboratories Ltd

REFERENCES

REFERENCESTeow Ket Seang, Issham Ismail and Abdul Razak. 2012. A Study of Formation Damage at Different Drilling Environment. Paper SPE 10029, 1982.Krueger, R. F. 2010. Overview of Formation Damage and Well Productivity in Oil Field Operations. Paper SPE 10029, 1982.Jiao, Di and Sharma, M.M. 2002. Formation Damage due to Static and Dynamic Filtration of Water Mud. Paper SPE 23823 presented at the SPE International Symposium on Formation Damage Control, Lafayette, Louisiana.