Objectif THE AIM OF THIS PROJECT IS TO DEVELOP A SERIES OF GUIDELINES WHICH CAN BE USED IN DESIGNING PRODUCTION PROCEDURES FOR USE IN SPECIFIC RESERVOIRS IN ORDER TO MINIMIZE FORMATION DAMAGE DUE TO CLAY REACTIONS WITH THE FLUIDS USED IN TERTIARY OIL PRODUCTION.Chemical reactions between large range of naturally occurring reservoir clays and an equally wide range of actual (or potential) components of fluids used in drilling and production operations were evaluated and the type of formation damage most likely to occur as a result of specific chemical reactions was documented in order to develop a series of guidelines which can be used in the design of drilling and production procedures for use in specific reservoirs.Kaolinite proved to be very soluble in alkali runs. Congruent dissolution was observed; substantial solution concentrations of silicon hydroxide ions and aluminium hydroxide ions were indicated. Flow experiments confirmed that kaolinite is particularly reactive in alkaline solutions and moreso than other clays. Hence, high alkalinity water based drilling muds (WBM) and alkaline slugs used in some enhanced oil recovery (EOR) procedures will both selectively dissolve kaolinite and add silicon and aluminium solutes to pore fluids.Partial dissolution of kaolinite will tend to dislodge pore lining material and exacerbate fines migration and dilution or modification of fluids within the reservoir might lead to precipitation of gels or authigenic crystalline precipitates thus exacerbating reservoir scaling problems.Batch experiments demonstrated the extreme reactivity of chlorites: greatly so in acids but also in alkaline solutions. Data demonstrated more than 40% dissolution after only 2 days at 80 C. In acid solutions aluminium is preferentially dissolved (nonstoichiometric dissolution) which means that a potentially reactive silica rich residue must remain. Flow experiments confirm great reactivity.All acid treatments are potentially damaging where chlorites are concerned.Smectite (dioctahedral) was rather more acid sensitive than either illite or illite smectite (IS) clays although both illites and IS clays were rather more sensitive to acids than to alkalis. Dissolution was more or less stoichiome tric in acid solutions but alkalis peferentially leach silicon. Overall, illites were the least reactive of the clays. The findings indicated that illitic reservoirs in general are less susceptible to chemical damage than most others. The nature of illitic reservoirs is such (major permeability problems) that any damage is serious.THE REACTIONS OF ACTUAL OR POTENTIAL COMPONENTS OF FLUIDS USED IN DRILLING AND PRODUCTION OPERATIONS WITH CLAY MINERALS WHICH OCCUR AS GRAIN COATINGS IN OIL RESERVOIRS GIVE RISE TO IMPORTANT ROCK PERMEABILITY MODIFICATIONS WITH CONSEQUENCES IN OIL RECOVERY EFFICIENCY. A MANY STEP STUDY IS PROPOSED TO SHED LIGHT IN THE INVOLVED PHENOMENA. 15 TO 20 POSSIBLY MONOMONERALLIC CLAYS FROM THE KAOLINITE, SMECTITE, ILLITE AND CHLORITE GROUPS AS WELL AS FROM " INTERSTRATIFIED " CHLORITE/VERMICULITE, CHLORITE/SMECTITE AND ILLITE/SMECTITE FAMILIES WILL BE COLLECTED, MAINLY BY SUITABLE TREATMENT OF CORES AVAILABLE FROM VARIOUS SOURCES SO AS TO BE TRULY REPRESENTATIVE. SFTER CHARACTERIZATION BY XRD AND SEM THEY WILL BE SUBMITTED TO TREATMENT WITH AQUEOUS SOLUTIONS OF EACH OF THE ENVISAGED FLUID COMPONENTS (NAOH, HCL, KCL, CITRIC ACID, EDTA). TWO KINDS OF EXPERIMENTS ARE DEVISED SO AS TO ALLOW CLAY STRUCTURAL CHANGES (E G MODIFIED SWELLING BEHAVIOUR) AS WELL AS SOLUTION VARIATIONS TO BE STUDIED ONE AT THE TIME. ON SELECTED MINERAL/SOLUTE PAIRS KINETIC MEASUREMENTS WILL BE CONDUCTED UNDER VARIOUS TEMPERATURES, MINERAL SURFACE AREA, REACTANT CONCENTRATION AND SOLUTION/SOLID VOLUME RATIO IN ORDER TO PERMIT THE PREDICTION OF THE TIME SCALE AND SPATIAL EXTENT OF DAMAGE IN ACTUAL WELL TREATMENTS. GEL FORMATION INTO THE ROCK PORES, DUE TO PRECIPITATION OF PREVIOUSLY DISSOLVED FE, AL AND SI, WILL ALSO BE EXAMINED BOTH OUTSIDE THE POROUS MEDIUM AND WITHIN IT. FLOW EXPERIMENTS WILL BE CONDUCTED IN A POURPOSEDLY DESIGNED CELL ON VARIOUS ORIGINAL SANDSTONE CORE SAMPLES TO GAIN INFORMATION AS TO EXTENT OF PERMEABILITY MODIFICATIONS ARISING FROM CLAY REACTION AS WELL AS TO ITS CONSEQUENCIES. NEW DRILLING AND PRODUCTION PROCEDURE DESIGN WILL THEN FOLLOW, WHICH WILL MINIMIZE CLAY-DEPENDENT DAMAGE. MUCH EFFORT WILL BE DEVOTED TO THE PREDICTION OF DIFFERENT TYPES OF GRAIN-COATING CLAYS IN RESERVOIR SANDSTONES, THUS POTENTIAL PRODUCTION PROBLEMS MIGHT BE ANTICIPATED. BOTH CAREFUL LITERATURE SURVEY AND THERMOCHEMICAL CALCULATION PROCEDURES WILL BE UNDERTAKEN TO THIS PURPOSE. Champ scientifique agricultural sciencesagriculture, forestry, and fisheriesagriculturegrains and oilseedsnatural scienceschemical sciencesinorganic chemistrypost-transition metalsengineering and technologymaterials engineeringcoating and filmsnatural scienceschemical sciencesinorganic chemistrymetalloids Programme(s) FP1-ENNONUC 3C - Research and development programme (EEC) in the field of Non-Nuclear Energy, 1985-1988 Thème(s) Data not available Appel à propositions Data not available Régime de financement CSC - Cost-sharing contracts Coordinateur UNIVERSITY OF SHEFFIELD Contribution de l’UE Aucune donnée Adresse WESTERN BANK S10 2TN SHEFFIELD Royaume-Uni Voir sur la carte Coût total Aucune donnée
