C6 sand control chapter

Designed & Presented by Mr ĐỖ QUANG KHÁNH, HCMUT 03/2014 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com Content & Agenda  Introduction  Causes and consequences of sand production  Sand Production Prediction  Sand control methods Ref:  Reservoir Stimulation, 3e – Economides & Nolte  Petroleum Production Systems - Economides et al., 1994  Production Operations: Well Completions, Workover, and Stimulation -Thomas O Allen, Alan P Roberts,1984 Introduction o Why Sand Control?  The production of formation sand with oil and/or gas creates a number of potentially dangerous and costly problems  Losses in production can occur as the result of sand partially filling up inside the wellbore  Creation of void and breakouts behind the casing, shale streaks remain unsupported and creation a formation damage in the near wellbore region  Sand & particles transported with fluids cause severe erosion damages, especially in gas wells  If the flow velocities of the well cannot transport the produced sand to the surface, this accumulation of sand may shut off production entirely  If shutoff occurs, the well must be circulated, or the sand in the casing must be bailed out before production can resume  Once produced sand is at the surface and no longer threatens to erode pipe or reduce productivity, the problem of disposal remains Sand disposal can be extremely costly, particularly on offshore locations Introduction When is Sand Control Required? CAUSES OF SAND PRODUCTION Sand grain slippage, collapse of the perforation tunnel, wellbore or cavity, resulting from:     A significant pressure gradient across the sandface This can result from:    high drawdowns; pressure depletion; wellbore deviation; pressure surges during rod pumping high fluid viscosities (>50 cp,), especially in heavy oil wells where viscosities may exceed 1000 cp; turbulence in the pore throats in gas wells and high-rate or high gas-liquid ratio (GLR) oil wells; formation damage and plugging of perforations and pore throat areas Increasing water saturation and water cuts, which destabilize the sand as a result of:      reduction in the cohesive strength and inter-granular friction mobilization of the fines from around the grain-to-grain contacts chemical reaction with the natural cementing materials, especially if salinity changes occur with water breakthrough operators increasing the gross production rate and draw-down to compensate for decreasing relative permeability to oil and oil production volumes increasing drag forces on the grains due to movement of the wetting phase (i.e., the connate water) Initiation OF SAND PRODUCTION Sand production is initiated when the forces acting to dislodge sand grains from the formation exceed the strength of the rock  Dislodging forces included mechanical stresses in the rock and the drag forces associated with fluid flow  Pore pressure relieves frictional forces  Production of wetting phase reduces capillary pressure forces    Resisting forces include rock strength parameters and capillary pressure forces Intergranular frictional forces and bonding (cementation) help resist grain movement Capillary Pressure adds further grain-to-grain bonding Initiation OF SAND PRODUCTION Sand production is initiated when the forces acting to dislodge sand grains from the formation exceed the strength of the rock  Dislodging forces included mechanical stresses in the rock and the drag forces associated with fluid flow  Pore pressure relieves frictional forces  Production of wetting phase reduces capillary pressure forces  Resisting forces include rock strength parameters and capillary pressure forces  Intergranular frictional forces and bonding (cementation) help resist grain movement  Capillary Pressure adds further grain-to-grain bonding  • • • • Sand Production May Begin Late in the Life of a Well Pressure pulses caused by non-steady production Increasing mechanical stresses caused by pore pressure reduction Increased drawdown leads to increased drag forces Water breakthrough can severely reduce capillary pressure forces Effects OF SAND PRODUCTION  Accumulation in surface equipment – Increased maintenance costs – Costs associated with deferred production  Accumulation downhole – Frequent clean-out trips – Decreased productivity  Erosion of downhole and surface equipment – Frequent workovers  Formation collapse and casing damage – Loss of well Prediction OF SAND PRODUCTION  • • •  Sand Production Prediction Determine which wells have the potential for sand production Determine best time to institute sand control methods Assess economic impact (both positive and negative) of incorporating sand control Probability of Successful Sand Production Prediction • • • • • Typically good prediction in “definitely will” or “definitely will not” fail categories Majority of the wells and reservoirs fall in between these two extremes Marginal formations difficult to accurately predict Multi-phase fluid flow is a complicating factor Effects of changing production character difficult to predict  Sand Prediction and Sand Control • Most authorities recommend that sand control techniques be applied immediately upon indication that a formation will produce sand This practice will allow the highest success rate and the lowest production loss possible after sand control is applied Laboratory studies have shown that once an unconsolidated sand is disturbed, the sand cannot be packed back to its original permeability Sand control should be applied before the reservoir rock is seriously disturbed by sand production • • • The factors tending to prevent sand production The amount, strength, and nature of the rock cementation The shape and arrangement of the sand grains, which will determine the inter- granular friction The degree of compaction, which is generally proportional to the overburden loading (or depth) and inversely proportional to the initial reservoir pressure The behavior of the rock after initial failure in terms of:  plastic deformation of the cavity wall;  natural arching of the unconsolidated or failed sand around the perforation tunnel Rate Exclusion or Production Restriction  Rate Exclusion or Production Restriction Reduction in prod rate will reduce drag forces and drawdown to provide reduced risk of sand production Procedure: – Slowly increase rate until sand production begins to increase (Critical Drawdown) – Sequentially reduce flow rate until the sand production declines to an acceptable level Attempting to establish maximum flow rate in conjunction with stable arch   Horizontal Wells??? Limitations The reduced production rate that excludes formation production sand is not profitable Production rate is not always the only factor contributing to sand production The degree of consolidation of the formation, the type and amount of cementitious material present, and the amount of water being produced are also significant contributing factors to sand production These other factors may allow a well to produce sand even after the production rate has been severely restricted Selective Completion Practices Selective Completion Practices  Perforate or complete only high strength layers  Perforate at high shot density  Need good hydraulic communication  Poor sweep efficiency  Risk to leave reserves unrecovered Plastic Consolidation  Plastic Consolidation Goal is to inject plastic resins into the formation to provide increased compressive strength while maintaining acceptable permeability Treatment objective are: – Cover entire perforated interval – Coat all sand grains with resin – Concentrate resin at contact points – Leave pore spaces open Three types of resins systems available: – Epoxies – Furans (and furan/phenolic blends) – Phenolics Plastic Consolidation  Plastic Consolidation Placement Technique Verify rock wettability Pump a preflush treatment to restore water wettability Pump the treatment inside the formation Wait for rock grains coating Flush back the excess treatment fluids  Pros and Cons of Plastic Consolidation Treatments Plastic Consolidation  Resin Coated Gravel Resin coated gravel or gravel mixed in a resin carrier fluid is pumped to fill voids behind casing and perforation tunnels Resin is allowed to consolidate Casing is drilled out to leave wellbore unobstructed  Resin Coated Gravel Limitations Must have complete coverage of perforated interval to be successful Good compressive strength of resin coated gravel requires high temperature (>300ºF) May reduce near-wellbore permeability Long term reliability  Resin Coated Gravel Screenless Frac-Pack Similar to resin coated gravel treatment, but gravel placed above fracture pressure Gravel is underflushed at end of fracture job and allowed to cure Casing is drilled out to leave wellbore unobstructed StandAlone Screens and Slotted Liners  StandAlone Screens and Slotted Liners Slotted liner or screen used as a down hole filter Widely applied in open hole horizontal wells with mixed success Reduced productivity, plugging or erosion caused by resorting of formation material can occur in poorly sorted formations Best used for well-sorted clean sands with large grain size Doomed to failure in cased hole environment  Main Applications for Standalone Screens Open hole completions High permeability, uniform formations (d40/d90 < 3) Screen opening sized to retain largest d10 fraction of formation sand Screen diameter as large as possible StandAlone Screens and Slotted Liners  Screen and Slotted Liner Screen or slotted liner openings are referred in gauge, inches, or microns Gauge is the opening in inches X 1000 (i.e., 010” is 10 gauge); Inches = 25.4 Millimeters; Design point: openings = d10  Annular Flow Why is annular flow a problem? – Annular velocity causes sand face erosion and screen erosion – Annular velocity causes dynamic sorting of fines in the annulus => plugging, hot spots, and erosion – Annular flow is the dominant failure mechanism in standalone screen completions StandAlone Screens and Slotted Liners  Schematic of Screen Plugging  “Hot-spot” vs Uniform Formation Collapse StandAlone Screens and Slotted Liners      Performance of Screens is Based on: Sand retention Resistance to plugging from formation material Resistance to plugging from mud flow through screen These must be determined through laboratory testing – no standard theory exists – current criteria based on empirical studies Screen Type Comparison StandAlone Screens and Slotted Liners      Slotted Liner Geometries Single slot staggered rows are preferred for higher strength Minimum slot width is 012”, but practical minimum width is 0.020” Small slot widths reduce inflow area and increase cost Only advantage of slotted liner over screen is low cost!      Wire Wrapped Screen Prepack Screen Premium Screens Screens with Inflow Control Devices (ICD) Expandable Screen Gravel Packing  Gravel Packing Uses high permeability gravel in conjunction with slotted liner or screen Formation material bridges on larger, specially sized gravel, which in turn bridges on a screen or slotted liner Tightly packed gravel is stable, preventing shifting and resorting of formation sand Most reliable and most widely applied sand control technique  Gravel Pack Schematic Gravel pack sand must be properly sized to control formation sand Screen openings must be properly sized to control gravel pack sand Gravel Packing  Gravel Pack Sand Selection Procedure Obtain formation sand sample Determine formation grain size and distribution Determine required gravel size Determine required screen openings Determine type of gravel  Saucier’s Experiment Establish initial flow rate (qi) and stabilized pressure drop, calculate initial permeability (ki) Increase flow rate and establish new stabilized pressure drop Reduce flow rate to initial rate (qi) and establish stabilized pressure drop, calculate final permeability (kf) Optimum sand control occurs when kf= k Gravel Packing  Saucier’s Results  Application of Saucier’s Results Gravel pack sand permeability is a function of grain size (as D50increases, permeability increases) D50 of the gravel pack sand is a function of d50 of the formation sand to achieve sand control as per Saucier D50 must be optimized to achieve maximum gravel pack sand permeability, yet still maintain sand control Gravel Packing  Optimization of Gravel Pack Sand Size  Commonly Available Gravel Sizes  Gravel Pack Sand Design Procedure Construct a representative sieve analysis curve for the formation sand Determine d50 of the formation sand Multiply the d50 value by to achieve D50 of the gravel pack sand Select gravel pack sand with D50 < (6 x d50) Different layers in the formation sand may indicate different required gravel sizes Generally, the smallest indicated gravel size is selected Techniques for Handling Produced Sand ... widely applied sand control technique  Gravel Pack Schematic Gravel pack sand must be properly sized to control formation sand Screen openings must be properly sized to control gravel pack sand... changing production character difficult to predict  Sand Prediction and Sand Control • Most authorities recommend that sand control techniques be applied immediately upon indication that a formation... possible after sand control is applied Laboratory studies have shown that once an unconsolidated sand is disturbed, the sand cannot be packed back to its original permeability Sand control should