Hall of Fame

home *** CD-ROM | disk | FTP | other *** search

/ Hall of Fame / HallofFameCDROM.cdr / oilfield / condor.lzh / BUILDUP.DOC < prev next >

Wrap

Text File | 1991-01-12 | 24KB | 530 lines

OIL/GAS WELL BUILDUP ANALYSIS PROGRAM DOCUMENTATION --------------------------------------------------- PROGRAM DESCRIPTION ------------------- PURPOSE: TO ANALYZE PRESSURE BUILDUP TESTS FOR HYDRAULICALLY FRACTURED WELLS, ACIDIZED WELLS OR NATURAL COMPLETIONS. THE PROGRAM DETERMINES PERMEABILITY, SKIN FACTOR, FRACTURE HALF LENGTH, FRACTURE CAPACITY, INITIAL (OR AVG) RESERVOIR PRESSURE, AND PROVED DRAINAGE RADIUS. FOR GAS WELLS IT WILL ALSO ANALYZE WELLBORE/FRACTURE STORAGE VOLUME AND TURBULENCE. OPTIONS: (1) FRACTURE FLOW ANALYSIS - FOR FRACTURED WELLS WITH LIMITED CONDUCTIVITY FRACTURES (2) RADIAL FLOW ANALYSIS - FOR NATURAL COMPLETIONS OR FRACTURED WELLS IN TRANSIENT PSEUDORADIAL FLOW (3) LATE TIME ANALYSIS - FOR WELLS SHUT IN LONG ENOUGH FOR BOUNDARIES TO HAVE INFLUENCE (MODIFIED MUSKAT METHOD) INPUT: EFFECTIVE PRODUCTION TIME PRIOR TO TEST FINAL FLOW RATE PRIOR TO TEST PRESSURE BUILDUP DATA (SHUTIN TIMES & BOTTOM HOLE PRESSURES) RESERVOIR TEMPERATURE TOTAL POROSITY CRITICAL WATER SATURATION NET PAY THICKNESS ADDITIONAL INPUT FOR GAS WELLS: SEPARATOR GAS GRAVITY DEPTH AND FLOWSTRING I.D. (I.E. WELLBORE STORAGE VOLUME) FRACTURE STORAGE VOLUME ADDITIONAL INPUT FOR OIL WELLS: OIL FORMATION VOLUME FACTOR (Bo) OIL VISCOSITY (Uo) OIL COMPRESSIBILITY (Co) OUTPUT: PERMEABILITY (k) SKIN FACTOR (S) EFFECTIVE WELLBORE RADIUS (Reff) FRACTURE HALF LENGTH (Xf) FRACTURE CAPACITY (Kf width) DIMENSIONLESS FRACTURE CAPACITY (Fcd defined by Agarwal) INITIAL RESERVOIR PRESSURE (IF IN TRANSIENT FLOW) AVERAGE RESERVOIR PRESSURE (IF IN PSEUDO STEADY STATE FLOW) TIME REQUIRED TO REACH BOUNDARY PROVED DRAINAGE RADIUS DURING BUILDUP TEST USES: (1) CAN ANALYZE GAS WELLS, GAS/CONDENSATE WELLS, OIL WELLS, OIL/WATER WELLS, AND WATER WELLS. (2) CAN ANALYZE SURFACE OR BOTTOM HOLE SHUT IN PRESSURE DATA FROM DRILL STEM TESTS, COMPLETION REPORTS, DAILY GAUGE REPORTS, OR BOTTOM HOLE BOMBS. (3) CAN DETERMINE THE NEED OR EFFECTIVENESS OF STIMULATION IN TERMS OF THE SKIN FACTOR, FRACTURE LENGTH, FRACTURE CONDUCTIVITY, AND THE EFFECTIVE WELLBORE SIZE. (4) CAN DETERMINE THE INSITU PERMEABILITY OF THE RESERVOIR (5) BOUNDARY EFFECTS AND RESERVOIR SIZE CAN BE ESTIMATED IN LIMITED SIZE RESERVOIRS. (6) WELLBORE AND FRACTURE STORAGE VOLUME CAN BE ESTIMATED FOR GAS WELLS AND GAS/CONDENSATE WELLS (7) CAN USE RESULTS AS INPUT FOR GAS WELL RESERVOIR SIMULATOR THEORY: (1) PRESSURE FUNCTIONS ARE EVALUATED USING REAL GAS PSEUDO PRESSURES, I.E. THE M(P) FUNCTION OF AL-HUSSAINY. (2) TIME FUNCTIONS ARE EVALUATED USING TWO EXPRESSIONS DEVELOPED BY R.G. AGARWAL - EFFECTIVE TIME AND REAL GAS PSEUDO TIME. EFFECTIVE TIME CORRECTS FOR THE EFFECTS OF THE PRODUCING TRANSIENT ON THE BUILDUP CURVE. THE REAL GAS PSEUDO TIME CORRECTS FOR THE VARIATIONS OF GAS VISCOSITY AND COMPRESSIBILITY AS A FUNCTION OF PRESSURE. (3) WELLBORE STORAGE EFFECTS ARE ACCOUNTED FOR USING THE THEORIES OF H.J. RAMEY, JR. AND R.E. GLADFELTER. (4) PERMEABILITY AND SKIN FACTOR ARE EVALUATED BY PSEUDO HORNER ANALYSIS OR BY MUSKAT'S AVERAGE PRESSURE METHOD. (5) DIMENSIONLESS FRACTURE CONDUCTIVITY (Fcd) IS DEFINED BY AGARWAL (SPE #6838) AND GENERALLY RANGES FROM ABOUT 0.01 FOR VERY LOW CONDUCTIVITY FRACTURES TO ABOUT 500 FOR VERY HIGH CONDUCTIVITY FRACTURES. (6) FRACTURE PROPERTIES ARE EVALUATED USING CORRELATIONS DEVELOPED BY J. O. SCOTT WHICH RELATE THE TRANSIENT PRERADIAL LOG-LOG SLOPE TO FRACTURE CONDUCTIVITY AND FRACTURE HALF LENGTH. (7) INITIAL RESERVOIR PRESSURE IS EVALUATED USING THE THEORIES OF R.G. AGARWAL AND J.O. SCOTT. (8) AVERAGE RESERVOIR PRESSURE IS EVALUATED USING THE THEORIES OF MUSKAT , H.J. RAMEY, JR., AND W.M. COBB. INSTALLATION INSTRUCTIONS ------------------------- THE DISK WHICH YOU PURCHASED MAY NOT HAVE ENOUGH FREE SPACE LEFT TO RUN THE BUILDUP.EXE MODULE. IN ORDER TO INSTALL THIS SOFTWARE PLEASE FOLLOW THESE STEPS: IF YOU HAVE A HARD DRIVE SIMPLY COPY THIS DISK TO YOUR HARD DRIVE THEN IT IS READY TO RUN. IF YOU DON'T HAVE A HARD DRIVE, THEN COPY BUILDUP.EXE ALONG WITH PLOT, TABL, AND CALC TO A SECOND FLOPPY DISK. THEN COPY EVERYTHING ELSE TO A THIRD FLOPPY DISK. WHEN YOU HAVE AN INPUT DATA FILE READY TO RUN THEN COPY IT TO THE SECOND FLOPPY DISK. THEN RUN BUILDUP.EXE FROM THE SECOND DISK. YOU MAY ALSO NEED TO COPY YOUR PRINT.COM TO THE SECOND DISK TO GET PRINTOUTS. DEFINITION OF INPUT VARIABLES ----------------------------- TOTAL POROSITY - IS THE POROSITY OBTAINED FROM WELL LOG INTERPRETATION CRITICAL WATER SATURATION FOR GAS WELLS - IF THE WELL DOES NOT PRODUCE ANY FLUIDS THEN USE THE INITIAL WATER SATURATION OBTAINED FROM THE LOGS. IF THE WELL PRODUCES FLUIDS THEN USE THE CRITICAL WATER SATURATION WHICH WILL BE LESS THAN THE INITIAL WATER SATURATION. CRITICAL WATER SATURATION FOR OIL WELLS - IF THE WELL DOES NOT PRODUCE ANY WATER THEN USE THE INITIAL WATER SATURATION OBTAINED FROM THE LOGS. IF THE WELL PRODUCES WATER THEN USE THE CRITICAL WATER SATURATION WHICH WILL BE LESS THAN THE INITIAL WATER SATURATION. CRITICAL WATER SATURATION FOR WATER WELLS - ALWAYS USE THE CRITICAL WATER SATURATION WHICH WILL BE LESS THAN THE INITIAL WATER SATURATION. EXECUTABLE MODULES ------------------ YOU WILL HAVE THE FOLLOWING EXECUTABLE MODULES: BUILDUP - THIS PERFORMS A BUILDUP ANALYSIS ON ANY WELL. THIS IS THE MAIN MODULE WHICH WILL ANALYZE BUILDUP TESTS FOR GAS WELLS, GAS/CONDENSATE WELLS, OIL WELLS, OIL/WATER WELLS, AND WATER WELLS. BE SURE THAT A DATA FILE ALREADY EXISTS FOR THE WELL YOU WANT TO ANALYZE BEFORE RUNNING THIS MODULE. BUILDUP DATA FILES CAN BE CREATED WITH EITHER BUINPUT1.EXE OR BUINPUT2.EXE WHICH ARE EXPLAINED BELOW. IF YOU ARE GOING TO ANALYZE AN OIL WELL, AN OIL/WATER WELL, OR A WATER WELL THEN ALSO BE SURE THAT YOU HAVE RUN THE OILPROP.EXE MODULE FIRST IN ORDER TO DETERMINE NECESSARY FLUID PROPERTIES WHICH YOU WILL BE PROMPTED FOR. BUINPUT1 - USE THIS MODULE IF YOU HAVE DATA FROM A BOTTOM HOLE BOMB. YOU WILL BE PROMPTED FOR BASIC INFORMATION, THE CUMULATIVE PRODUCTION TIME, THE NUMBER OF SHUTIN DATA POINTS, AND EACH POINT'S SHUTIN TIME AND PRESSURE. THIS MODULE CAN BE USED FOR GAS WELLS, GAS/CONDENSATE WELLS, OIL WELLS, OIL/WATER WELLS, AND WATER WELLS. BUINPUT2 - THIS MODULE CAN ONLY BE USED FOR GAS WELLS OR FOR GAS/CONDENSATE WELLS. USE THIS MODULE IF YOU HAVE SURFACE SHUTIN PRESSURES TO ANALYZE. THIS MODULE WILL ESTIMATE THE BOTTOM HOLE SHUTIN PRESSURES AND SAVE THEM IN THE INPUT DATA FILE. YOU WILL BE PROMPTED FOR BASIC INFORMATION, CUMULATIVE PRODUCTION TIME, AND OTHER PARAMETERS NEEDED TO CALCULATE BOTTOM HOLE PRESSURES FROM SURFACE PRESSURES SUCH AS WELL DEPTH, GAS GRAVITY, OIL GRAVITY, TUBING I.D., BOTTOM HOLE TEMP., ETC. THIS MODULE IS COMMONLY USED TO ANALYZE SHUTINS REPORTED ON GAS WELL DAILY GAUGE REPORTS. OILPROP - THIS MODULE IS USED TO ESTIMATE THE RESERVOIR FLUID PROPERTIES IF A FLUID ANALYSIS IS NOT AVAILABLE. IT USES STANDARD CORRELATIONS TO ESTIMATE FLUID PROPERTIES SUCH AS FORMATION VOLUME FACTOR, COMPRESSIBILITY, AND VISCOSITY FOR BOTH OIL AND WATER. IT CAN ALSO BE USED TO ESTIMATE THE INITIAL BUBBLE POINT PRESSURE IF IT IS NOT KNOWN. IN ORDER TO GET A PRINTOUT OF THE RESULTS BE SURE TO TYPE "Ctrl-PrtSc" PRIOR TO RUNNING THIS MODULE. BE SURE TO TYPE "Ctrl-PrtSc" AGAIN WHEN YOU ARE FINISHED. DATA FILES ---------- YOU WILL HAVE THE FOLLOWING INPUT DATA FILES: GASWELL.BU (SAMPLE GAS BUILDUP ANALYSIS) ----------------------------------------- YOU MAY WANT TO LEARN TO USE THIS PROGRAM BY USING THIS SAMPLE DATA FILE. IF YOU DO THEN USE THE FOLLOWING INPUT PARAMETERS: GAS GRAVITY (0.60), CUMULATIVE PRODUCTION TIME (672 HOURS), BOTTOM HOLE TEMP (189 F), FINAL GAS FLOW RATE (740 MCFD), FRACTIONAL WATER SATURATION (0.20), TOTAL FRACTIONAL POROSITY (0.12), NET PAY (18 FT), WELL DEPTH (8100 FT) & TUBING ID (1.995). POINTS "A" AND "H" ARE REASONABLE CHOICES FOR ANALYSIS. IF YOU HAVE A DEMO DISK, THEN SOME OF THESE PARAMETERS WILL NOT BE ABLE TO BE CHANGED EVEN FROM THE PROMPTS. OTHERWISE, THE DEMO DISK WILL DO EVERYTHING ELSE THE ACTUAL PROGRAM DOES. OILWELL.BU (SAMPLE OIL BUILDUP ANALYSIS) ---------------------------------------- YOU MAY WANT TO LEARN TO USE THIS PROGRAM BY USING THIS SAMPLE DATA FILE. IF YOU DO THEN USE THE FOLLOWING INPUT PARAMETERS: FVF or Bo (1.25), CUMULATIVE PRODUCTION TIME (22.5 HRS), BOTTOM HOLE TEMP (260 F), FINAL OIL FLOW RATE (790 STBD), FRACTIONAL WATER SATURATION (0.25), TOTAL FRACTIONAL POROSITY (0.15), NET PAY (30 FT), OIL VISCOSITY (1.0) AND OIL COMPRESSIBILITY (12.5). POINTS "A" AND "C" ARE REASONABLE CHOICES FOR ANALYSIS. IF YOU HAVE A DEMO DISK, THEN SOME OF THESE PARAMETERS WILL NOT BE ABLE TO BE CHANGED EVEN FROM THE PROMPTS. OTHERWISE, THE DEMO DISK WILL DO EVERYTHING ELSE THE ACTUAL PROGRAM DOES. NEW DATA FILES WITH THE SAME FORMAT AS THOSE INCLUDED CAN BE CREATED BY EXECUTING EITHER BUINPUT1 OR BUINPUT2. WHEN CREATING A NEW INPUT DATA FILE WITH EITHER BUINPUT1 OR BUINPUT2 ENTER UP TO AN 8 CHARACTER ALPHANUMERIC NAME FOLLOWED BY A PERIOD AND UP TO A 3 CHARACTER ALPHANUMERIC NAME. FOR EXAMPLE IF THE NAME OF THE WELL YOU ARE GOING TO ANALYZE IS ANNA #1-12, THEN FOR AN INPUT FILE NAME YOU MIGHT ENTER "ANNA1-12.BU" AT THE PROMPT. DATA LIMITATIONS ---------------- A MAXIMUM OF 52 FLOW DATA POINTS MAY BE USED BY THE PROGRAM FOR AN ANALYSIS. HOWEVER, A MAXIMUM OF 500 DATA POINTS MAY BE IN THE INPUT DATA FILE. DATA POINTS MAY BE SKIPPED FROM BEING READ BY THE PROGRAM BY SIMPLY TYPING " SKIP" IMMEDIATELY AFTER AN INPUT LINE IN THE DATA FILE AS SHOWN IN THE SAMPLE DATA FILE BELOW. THIS IS DONE AFTER THE INPUT FILE IS CREATED WITH ANY TEXT EDITOR. IT IS COMMON TO SKIP DATA POINTS WHICH ARE SHUTIN TIMES OF LESS THAN ONE HOUR SINCE THEY WILL USUALLY HAVE SIGNIFICANT STORAGE EFFECTS. ALL DATA POINTS MUST BE ENTERED IN INCREASING TIME SEQUENCE. ALL PRESSURES MUST BE IN INCREASING PRESSURE SEQUENCE. IF YOU HAVE SOME POINTS WHICH HAVE DECREASING PRESSURES WITH TIME DUE TO PHASE RESEGREGATION OR WHATEVER, THEN YOU MUST EXCLUDE THESE POINTS FROM THE ANALYSIS. SAMPLE DATA FILE ---------------- BELOW IS PART OF THE OILWELL.BU OIL INPUT DATA FILE. IT SHOWS HOW TO SKIP SELECTED INPUT DATA POINTS FROM BEING ANALYZED. NOTE THAT THE SHUTIN POINTS AT .05, .083, .15 .267, .5, AND .667 WERE SKIPPED BECAUSE OF THE WORD "SKIP" ON EACH OF THESE LINES. OILWELL #1 BLACK GOLD PRODUCTION CO. SW/4 SEC. 11-28S-42W STANTON CO., KS. MISENER 01-01-91 22.5 CUMULATIVE PRODUCING HOURS .000 3097.0 .050 3105.0 SKIP .083 3108.0 SKIP .150 3115.0 SKIP .267 3125.0 SKIP .500 3139.0 SKIP .667 3146.0 SKIP 1.100 3159.0 1.670 3171.0 2.300 3180.0 4.200 3195.0 5.570 3203.0 7.050 3208.0 9.570 3216.0 12.980 3222.0 18.200 3228.0 27.900 3234.0 36.430 3238.0 44.720 3242.0 60.300 3246.0 OUTPUT FILES CREATED -------------------- THE FOLLOWING OUTPUT FILES WILL BE CREATED WHEN YOU RUN THE BUILDUP.EXE MODULE: PLOT - IS A DATA FILE CREATED IF YOU SAVE ANY PLOTS TO A FILE. THERE IS ALSO AN OPTION TO SEND PLOTS DIRECTLY TO THE PRINTER. IF YOU SEND THE PLOTS DIRECTLY TO THE PRINTER THEN BE SURE TO RUN "PRINTER.COM" FIRST BEFORE RUNNING "BUILDUP". THE PRINTER PLOTS WILL CONTAIN MUCH HIGHER RESOLUTION PLOTS OF FIGURES 1 THRU 3 THAN THE PLOTS SHOWN ON THE COMPUTER SCREEN. ALL SCALING OF THE PLOTS IS DONE AUTOMATICALLY. ALL VALID DATA POINTS SELECTED FOR THE BUILDUP ANALYSIS WILL HAVE UNIQUE PLOT SYMBOLS. THE LAST DATA POINT USED IN YOUR INPUT FILE WILL ALWAYS BE THE PLOT SYMBOL "A". THE LAST 26 DATA POINTS WILL ALL BE CAPITAL LETTERS. THE 26 DATA POINTS BEFORE THESE WILL ALL BE LOWERCASE LETTERS. YOU WILL ALWAYS REFER TO A DATA POINT BY ITS PLOT SYMBOL, NOT ITS NUMBER. TABL - IS A DATA FILE ALWAYS CREATED WHEN YOU RUN THE BUILDUP PROGRAM. IT CREATES THE REPORTS CALLED "GAS WELL BOTTOM HOLE PRESSURE BUILDUP DATA" OR "OIL WELL BOTTOM HOLE PRESSURE BUILDUP DATA". CALC - IS A DATA FILE CREATED WHEN YOU USE THE CALCULATION OPTION TO ESTIMATE PERMEABILITY, SKIN FACTOR, INITIAL RESERVOIR PRESSURE, ETC. IT CREATES THE REPORTS "GAS WELL PRESSURE BUILDUP ANALYSIS CALCULATIONS" OR "OIL WELL PRESSURE BUILDUP ANALYSIS CALCULATIONS". THERE ARE THREE OPTIONS AVAILABLE FOR THE BUILDUP CALCULATIONS. OPTION 1 ASSUMES THAT THE TWO POINTS YOU SELECT ARE STILL IN PRERADIAL FRACTURE FLOW. OPTION 3 ASSUMES THAT THE TWO POINTS YOU SELECT ARE IN RADIAL FLOW. USE OPTION 2 IF SOMEWHERE BETWEEN THESE FLOW PATTERNS OR IF YOU KNOW THE INITIAL RESERVOIR PRESSURE. PRINTING OUTPUT FILES --------------------- YOU WILL COMMONLY WANT TO PRINT THE FOLLOWING OUTPUT DATA FILES: PLOT - FIGURES 1 THRU 4 (OR YOU MAY HAVE PRINTED PLOTS DIRECTLY) TABL - BOTTOM HOLE PRESSURE BUILDUP DATA CALC - PRESSURE BUILDUP ANALYSIS CALCULATIONS WHEN PRINTING THESE THREE OUTPUT DATA FILES, YOUR PRINTER SHOULD BE SET TO PRINT WIDE (ABOUT 130 CHARACTERS PER LINE). FOR NARROW PRINTERS THIS MEANS YOU SHOULD BE IN COMPRESSED PRINT MODE. I COMMONLY PRINT "TABL" AND "CALC" WITH COMPRESSED MODE AND 1/8" LINE SPACING, I.E. 8 LINES PER INCH. I COMMONLY PRINT "PLOT" WITH COMPRESSED MODE AND 4/72" LINE SPACING, I.E. 18 LINES PER INCH. FOR HP LASER JETS I USE 16 LINES PER INCH. YOU CAN SET LINE SPACING WITH A SIMPLE BASIC PROGRAM IF YOU KNOW THE COMMANDS FOR YOUR PRINTER. I HAVE INCLUDED A SAMPLE BASIC PROGRAM WHICH SETS THE LINE SPACING FOR EPSON PRINTERS AND HP LASER PRINTERS. PANASONIC PRINTERS CAN USE THE EPSON OPTION. TO USE THIS BASIC PROGRAM TYPE "BASIC PRINTER". THEN ENTER "1" FOR EPSON OR "2" FOR HP LASER JET. THEN ENTER "1" IF YOU ARE GOING TO PRINT "TABL" OR "CALC". ENTER "2" IF YOU ARE GOING TO PRINT "PLOT". BE SURE THAT BASIC.EXE IS IN YOUR PATH. AN EXECUTABLE VERSION OF THE PRINTER SETUP IS ALSO INCLUDED. IT IS CALLED "PRINTER.COM". THE SOURCE CODE IS PRINTER.PAS. CONSIDERATIONS WHEN RUNNING THE PROGRAM --------------------------------------- HOW TO HANDLE GAS WELLS PRODUCING WATER AND/OR CONDENSATE --------------------------------------------------------- IF STARTING WITH DATA FROM A BOTTOM HOLE BOMB, THEN USE BUINPUT1.EXE MODULE TO CREATE AN INPUT FILE FOR THE BUILDUP ANALYSIS. IF STARTING WITH DAILY GAUGE REPORTS, OR ANY OTHER SURFACE PRESSURE MEASUREMENTS, THEN USE THE BUINPUT2.EXE MODULE TO CREATE AN INPUT FILE FOR THE BUILDUP ANALYSIS. THE BUINPUT2.EXE MODULE WILL CALCULATE BOTTOM HOLE SHUTIN PRESSURES FROM THE WELLHEAD PRESSURES INCLUDING ADJUSTMENTS FOR CONDENSATE AND/OR WATER PRODUCTION AND THEN PLACE ALL NECESSARY INFORMATION INTO AN INPUT FILE. WHEN YOU ARE PROMPTED FOR THE FINAL GAS RATE ENTER THE GAS EQUIVALENT RATE WHICH INCLUDES THE GAS EQUIVALENT PRODUCTION OF THE CONDENSATE AND/OR WATER. THE PERMEABILITY AND PROVED ACRES CALCULATED WILL BE FOR THE COMBINED FLUID RATE. IF YOU WANT THE SAME VALUES FOR THE GAS ONLY, THEN YOU CAN MULTIPLY THESE VALUES BY THE RATIO OF GAS RATE TO EQUIVALENT GAS RATE. HOW TO HANDLE OIL WELLS PRODUCING WATER --------------------------------------- OIL WELLS WHICH PRODUCE WATER SHOULD BE HANDLED IN THE FOLLOWING MANNER. WHEN YOU ARE PROMPTED FOR THE FINAL OIL RATE ENTER THE FINAL TOTAL FLUID RATE INCLUDING OIL AND WATER IN STB PER DAY. WHEN YOU ARE PROMPTED FOR BO (FORMATION VOLUME FACTOR), UO (VISCOSITY), AND CO (COMPRESSIBILITY), ENTER WEIGHTED AVERAGE VALUES BASED ON THE PROPORTIONS OF OIL AND WATER FLOWING. THE PERMEABILITY AND PROVED ACRES CALCULATED WILL BE FOR THE COMBINED FLUID. IF YOU WANT THE SAME VALUES FOR THE OIL ONLY, THEN YOU CAN MULTIPLY THESE VALUES BY THE RATIO OF OIL RATE TO TOTAL FLUID RATE. THE ONLY LIMITATION OF APPLYING THIS METHOD IS THAT THE GAS SATURATION SHOULD BE LESS THAN THE CRITICAL SATURATION FOR FREE GAS FLOW. THE OIL AND WATER COMPRESSIBILITIES CALCULATED BY THE OILPROP.EXE MODULE ASSUME THAT THIS IS THE CASE. HOW TO HANDLE WATER WELLS ------------------------- WHEN YOU ARE PROMPTED FOR THE FINAL OIL RATE ENTER THE WATER RATE IN STB PER DAY. WHEN YOU ARE PROMPTED FOR BO (FORMATION VOLUME FACTOR), UO (VISCOSITY), AND CO (COMPRESSIBILITY), ENTER THE FLUID PROPERTIES OF THE PRODUCED WATER. THE PERMEABILITY AND PROVED ACRES CALCULATED WILL NOT NEED TO BE CORRECTED. DETERMINING RESERVOIR BOUNDARIES -------------------------------- RESERVOIR BOUNDARIES WILL TYPICALLY CAUSE THE SEMILOG HORNER SLOPE TO DOUBLE. THIS CAN EASILY BE VERIFIED BY SELECTING TWO POINTS FOR ANALYSIS (FROM FIGURE 2), CHOOSING THE CASE 3 OPTION (RADIAL FLOW), AND NOTING THE SEMILOG SLOPE DISPLAYED BOTH ON THE SCREEN AND ON THE REPORT. THEN SELECT TWO OTHER POINTS AND COMPARE THE SLOPES. THE SEMILOG SLOPES DISPLAYED WHEN YOU CHOOSE CASE 1 (FRACTURE FLOW) OR CASE 2 (PRESSURE KNOWN) ARE MODIFIED FOR FRACTURE BEHAVIOR AND SHOULD NOT BE USED FOR RESERVOIR BOUNDARY DETERMINATION. WHAT VALUE TO USE FOR CUMULATIVE PRODUCING TIME ----------------------------------------------- IF YOU HAVE THE DRAWDOWN.EXE MODULE IT WILL CALCULATE THE CORRECT VALUE OF PRODUCING TIME USING THE THEORY OF SUPERPOSITION. THIS SHOULD BE THE VALUE YOU SHOULD ENTER UNLESS THE WELL HAS REACHED STEADY STATE FLOW. SOMETIMES THE RATES VARY TOO MUCH, AND THEN AN ALTERNATIVE METHOD TO USE TO ESTIMATE CUMULATIVE PRODUCTION TIME IS TO DIVIDE THE CUMULATIVE PRODUCTION BY THE FINAL RATE AND THEN ADD 10 PERCENT TO THIS VALUE AFTER CONVERTING TO HOURS. THE EXTRA 10 PERCENT ACCOUNTS FOR THE DIFF- ERENCE BETWEEN CONSTANT PRESSURE TYPE CURVES AND CONSTANT RATE TYPE CURVES. IF THE WELL IS IN STEADY STATE FLOW THEN ENTER THE TIME IT TOOK TO REACH STEADY STATE FLOW. SHORT TESTS VS LONG TESTS ------------------------- ONE INTERACTIVE OPTION REQUIRES EXPLAINING. IT IS THE QUESTION WHICH SAYS: "ENTER (0) FOR DRILL STEM TEST OR A VERY SHORT TEST" "OR (1) FOR ANY OTHER BUILDUP TEST" TYPICALLY YOU WILL ENTER A "1" HERE. THE ONLY TIMES YOU WOULD ENTER A "0" WOULD BE WHEN ONE OF THE FOLLOWING CONDITIONS EXIST: A) POINTS YOU WANT TO SELECT HAVE SHUTIN TIMES OF LESS THAN 1 HOUR B) POINTS YOU WANT TO SELECT HAVE AGARWAL EFF TIME OF LESS THAN 1 HR. THE ONLY DIFFERENCE BETWEEN ENTERING A "0" OR A "1" FOR THIS OPTION IS THAT IF YOU ENTER A "1" THEN FIGURE 1 AND FIGURE 2 WILL AUTOMATICALLY SET THE MINIMUM VALUE OF THE X-AXIS TO 1, WHICH IS EQUIVALENT TO AN EFFECTIVE TIME OF 1 HOUR. THIS TYPICALLY ELIMINATES MANY OF THE EARLY TIME WELLBORE STORAGE POINTS. IF YOU ENTER A "0" THEN FIGURE 1 AND FIGURE 2 WILL USE THE VALUE OF THE FIRST VALID SHUTIN POINT TO CALCULATE THE MINIMUM VALUE OF THE X-AXIS, WHICH CAN THEN BE A NEGATIVE NUMBER. THIS WILL THEN PLOT ALL VALID DATA POINTS. THE ADVANTAGE OF SKIPPING THE EARLY DATA POINTS WHEN THEY ARE NOT GOING TO BE USED IS THAT THE RESOLUTION OF THE PLOTS WILL BE IMPROVED SINCE ALL SCALING IS DONE AUTOMATICALLY. IN OTHER WORDS, THE ONLY TIMES YOU MIGHT CONSIDER ENTERING A "0" FOR THIS OPTION WOULD BE FOR DRILL STEM TESTS, BUILDUP TESTS WHICH FOLLOW VERY SHORT FLOW TIMES, OR FOR WELLS WITH VERY HIGH PERMEABILITY. PREPARING FOR THE GAS SIMULATOR ------------------------------- AFTER RUNNING THE BUILDUP.EXE MODULE, THEN RUN THE BUTOGM.EXE MODULE TO CREATE AN INPUT FILE FOR THE GASMODEL.EXE MODULE IF THIS IS A GAS WELL OR A GAS/CONDENSATE WELL. IMPROVING RESOLUTION OF PLOTS ----------------------------- IF YOU NEED TO IMPROVE THE RESOLUTION OF THE PLOTS FROM FIGURES 1 THRU 4, SIMPLY LOOK AT THE FIGURES, DETERMINE WHICH POINTS YOU DO NOT NEED, GO BACK TO THE INPUT DATA FILE AND TYPE " SKIP" AT THE END OF THE APPROPRIATE LINES, AND THEN RERUN THE PROGRAM. WELLBORE/FRACTURE STORAGE CORRECTIONS FOR GAS WELLS --------------------------------------------------- BUILDUP DATA CAN BE CORRECTED FOR BOTH WELLBORE STORAGE EFFECTS AND FRACTURE STORAGE EFFECTS. THIS WILL BENEFIT THE BUILDUP ANALYSIS IN TWO WAYS. FIRST, MORE DATA POINTS WILL FALL ON THE STRAIGHT LINE FOR ANALYSIS. SECOND, THE SLOPE OF THE STRAIGHT LINE WILL BE MORE ACCURATE. IF YOU ANSWER "YES" TO THE STORAGE QUESTION, THEN YOU WILL NEED TO ENTER THREE ADDITIONAL PIECES OF INFORMATION. IN ORDER TO ESTIMATE THE WELLBORE STORAGE EFFECTS, THE DEPTH OF THE WELL AND THE I.D. OF THE FLOW STRING MUST BE ENTERED. IN ORDER TO ESTIMATE THE EFFECTS OF THE FORMATION FRACTURE STORAGE VOLUME, IT'S SIZE MUST BE ENTERED. IF THE GAS WELL HAS A PACKER, THEN YOU SHOULD ENTER THE I.D. OF THE TUBING. IF THE WELL DOES NOT HAVE A PACKER, THEN YOU SHOULD ENTER AN EQUIVALENT I.D. WHICH ACCOUNTS FOR BOTH TUBING AND ANNULAR VOLUME. WELLBORE/FRACTURE STORAGE CORRECTIONS FOR OIL WELLS --------------------------------------------------- THE CURRENT VERSION OF THIS PROGRAM DOES NOT HAVE THE ABILITY TO CORRECT FOR WELLBORE/FRACTURE STORAGE EFFECTS FOR OIL WELLS. THIS OPTION IS PLANNED FOR A LATER VERSION OF THIS PROGRAM. IT HAS BEEN MY EXPERIENCE THAT GENERALLY THE PERIOD OF TIME INFLUENCED BY WELLBORE STORAGE (1 TO 4 HOURS) IS ALSO INFLUENCED BY PHASE SEGREGATION EFFECTS. THEREFORE, EVEN IF YOU COULD CORRECT FOR WELLBORE STORAGE, YOU STILL COULD NOT CORRECT FOR PHASE SEGREGATION EFFECTS. THERE ARE CURRENTLY TWO TECHNIQUES WHICH CAN BE USED WHICH DESERVE TO BE MENTIONED HERE. THEIR REFERENCES ARE: 1. SELECTING WELLS WHICH RESPOND TO PRODUCTION-STIMULATION TREATMENT, API DRILLING AND PROD. PRAC., 1955, PP. 117-129, GLADFELTER, TRACEY, AND WILSEY. 2. EXTENSIONS OF PRESSURE BUILDUP ANALYSIS METHODS, JOURNAL OF PETROLEUM TECH., SEPTEMBER 1966, D.G. RUSSELL, PP. 1624-1636. BOTH OF THESE TECHNIQUES CAN BE PERFORMED WITHOUT TYPE CURVES. THE GLADFELTER METHOD REQUIRES BOTTOM HOLE PRESSURES AND EITHER FLUID COLUMN HEIGHTS OR TUBING AND CASING PRESSURES. THE RUSSELL METHOD ONLY REQUIRES BOTTOM HOLE PRESSURES.