PRESSURE TRANSIENT ANALYSIS (EXAMPLE ANALYSIS HORIZONTAL WELL) SMITH OIL COMPANY BUILDUP 7/1/99 THRU 7/17/99 Job #00000 The reports and plots contained herein are true and accurate representations of the input data; However, all interpretations are opinions based on analytical techniques described in the literature. ARC PRESSURE DATA, INC. cannot and does not, guarantee the accuracy or correctness of any interpretations. ARC PRESSURE DATA, INC. shall not, except in case of gross or willful negligence on our part, be liable or responsible for any loss, cost, damages, or expenses incurred or sustained resulting from any interpretations made by one of our officers, agents, or employees. Odessa, Texas Denton, Texas Sonora, Texas (800) 375-7728 (800) 573-2737 (915) 387-5982
NORTH TEXAS FIELD DENTON COUNTY, TX BUILDUP TEST DATES: 7/1/99-7/17/99 JOB #00000 DISCUSSION OF RESULTS INTRODUCTION An analysis was performed on the buildup data collected from the above mentioned well by ARC PRESSURE DATA, INC. The main test objective is to determine reservoir pressure. Alternate objectives include the formation skin, effective well length producing and permeability. The well was flowing at an average rate 2.139 MMcf/day GAS, 35.8 STB condensate/day, and 275.9 STBW/day prior to shut-in. A net producing time near 276 hours was estimated based on the cumulative production and time since the well was stimulated. The condensate stream was recombined to give a total wet stream gas production based on a correlation by Gold et. al. SUMMARY OF RESULTS Based on the log-log and derivative curve the inner boundary is best described by the Decreasing Storage w/ (-Step Model). The middle-time region is modeled by the Radial Homogeneous model with no-flow upper and lower boundaries for a horizontal well completion. The late-time data exhibits behavior resembling a single no-flow boundary near the well. This upward kick in the data can also be attributed to a composite change in well properties due to the condensate fallout or due to the lack of sufficient producing time. Because there was no obvious early or late-time radial flow response during this test, a type-curve fit was the method of analysis. Linear flow was exhibited through most of the middle-time region. It was only interrupted by changing wellbore storage and wellbore effects. The results of the best fit to the horizontal well model gave an effective radial permeability to gas to be 0.26 md with a total skin of 0.56. A very large vertical permeability to gas near 8.9 md shows evidence of excellent vertical communication, probably stemming from communication through natural or
drilling-induced fractures. An effective well length was determined to be 650 feet. This represents an analytical interpretation of the length of the lateral that is actually giving up production. The only sure way to verify this is through production logging, but this calculation has been supported by production logging results in other wells that we have been associated with. In order to derive this estimate, we made the assumption that the lateral penetrates the constant thickness about halfway over the whole length of the lateral. The extrapolated pressure, 2504.0, is essentially an intrinsic extrapolation of the model match to an infinite time. Extrapolation of the linear flow plot during the boundary response gives a maximum pressure at the boundary at the instant of shut-in near 2726.9. A straight line through the linear flow portion of the test on the square-root plot yields an effective well length of 648 feet. This agrees very well with the type-curve results. Also this linear flow plot shows an approximate doubling of slope, indicating the presence of a single no-flow boundary response. DISCUSSION OF RESULTS The producing time was somewhat shorter than the actual shut-in time. This can lead to erroneous results, especially the late-time response. In essence, the boundary response we see could simply be the lack of drawdown time to stabilize the transient profile in all directions from the well. It is not uncommon to see radially composite changes in mobility in condensate wells. Overall, considering the number of parameters estimated, the analytical match is relatively good for this test. If you have any questions concerning the results of the analysis, please call me at (800) 573-2737. Regards, Bill Jones Well Test Analyst
SUMMARY OF RESULTS SMITH OIL COMPANY JOB #00000 NORTH TEXAS FIELD (RED RIVER) DENTON COUNTY, TX BUILDUP 7/1/99 TO 7/17/99 FLOW REGIME MODELS: Inner Boundary Model:...Decreasing Storage w/ (-Step Model) Middle- Region Model:...Radial Homogeneous Outer Boundary Model:...Infinite-Acting PRESSURE DISTRIBUTION: Datum Depth... 10503 feet Initial Measured BHP... 1453.8 Final Measured BHP... 2197.1 Extrapolated (radius-of-influence) Pressure... 2504.0 RESERVOIR PROPERTIES: Effective Permeability to Gas... 0.26 md Vertical Permeability to Main Phase... 8.68 md Effective Producing Length... 650.0 feet Dimensionless Placement of Lateral... 0.5 WELLBORE / NEAR WELLBORE CONDITION: Wellbore Storage Coefficient... 1.97 bbl/psi Skin Factor... -0.56 BOUNDARY CONDITIONS: Distance to No-Flow Boundary, L1... 94 feet
100 Model Results Two no-flow boundaries - homogeneous Single fault Cs = 0.8889 bbl/psi Cd = 8710.0713 V = 1918.9742 bbl Lw = 972.2161 ft Log-Log Plot Delta m(p) (psi2/cp (*1E-06)) 10 1 Log-Log Plot Model Results Two no-flow boundaries - homogeneous - Single fault Stepped Wellbore Storage Wellbore storage coefficient Dimensionless wellbore storage Apparent wellbore volume Horizontal well length Log-Log Plot Line Details Line type : Linear flow through layer Slope : 0.5 Intercept : 4.33704 Coefficient of Determination : Not Used Line type : Wellbore storage Slope : 1 Intercept : 42.4038 Coefficient of Determination : Not Used Number of Intersections = 0 TP1 Pressure Radial Deriv 0.1 1 10 100 Equivalent (hours) - Tp=276.0 Value 0.8889 bbl/psi 8710.0713 1918.9742 bbl 972.2161 ft ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION
400 375 Linear Flow Plot TP1 Pressure 350 m(p) (psi2/cp (*1E-06)) 325 300 275 250 225 200 175 1: APPROXIMATE DOUBLING OF SLOPE Model Results Two no-flow boundaries - homogeneous Single fault Lw = 648.5281 ft Lw.h = 27238.1756 ft2 Sconv = 3.1765 P* = 2235.6179 150 5.95104 8.09905 10.2471 12.3951 14.5431 16.6911 Tandem Square-root Function - Tp=276.0 Linear Flow Plot Model Results Two no-flow boundaries - homogeneous - Single fault Stepped Wellbore Storage Horizontal well length Well length/layer thickness product Convergence skin Extrapolated pressure Linear Flow Plot Line Details Line type : Linear flow through layer Slope : -13.0148 Intercept : 384.607 Coefficient of Determination : 0.994888 Extrapolated m(p) Extrapolated pressure Value 648.5281 ft 2.7238e4 ft2 3.1765 2235.6179 Linear flow through layer 384.6071 psi2/cp (*1E-06) 2235.6179 Line type : Free model line Slope : -27.9949 Intercept : 544.896 Coefficient of Determination : Not Used ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION
Extrapolated m(p) Extrapolated pressure Number of Intersections = 0 SMITH OIL COMPANY Free model line 544.8962 psi2/cp (*1E-06) 2726.8579 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION
Delta m(p) (psi2/cp (*1E-06)) 1000 100 10 1 Match Results Two no-flow boundaries - homogeneous Single fault Kz = 8.6761 md K = 0.2568 md Zwd = 0.5 decimal fraction Cs = 0.9301 bbl/psi Cs2 = 1.9738 bbl/psi Tc = 0.05 hr S = -0.5551 Lw = 650.028 ft D = 0 1/(Mscf/day) L = 93.7633 ft Type Curve Plot 0.1 0.01 0.1 1 10 100 Equivalent (hours) - Tp=276.0 Type Curve Plot Model Results Two no-flow boundaries - homogeneous - Single fault Pressure Radial Deriv Stepped Wellbore Storage Vertical permeability Permeability Horizontal well position Value 8.6761 md 0.2568 md 0.5000 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION
m(p) (psi2/cp (*1E-06)) 400 375 350 325 300 275 250 225 Radial Flow Plot - MODEL MATCH OVERLAY Quick Match Results Two no-flow boundaries - homogeneous Single fault Constant compressibility Cs = 0.9301 bbl/psi Cs2 = 1.9738 bbl/psi Tc = 0.05 hr K = 0.2568 md Kz = 8.6761 md S = -0.5551 Zwd = 0.5 decimal fraction Lw = 650.028 ft D = 0 1/(Mscf/day) L NF = 93.7633 ft Pi = 2503.9954 200 175 Gen pressure TP1 Pressure 150 1 10 100 1000 10000 Horner Function - Tp=276.0 Quick Match Results Two no-flow boundaries - homogeneous - Single fault Stepped Wellbore Storage Wellbore storage coefficient Second Wellbore Storage Change for Second Storage Permeability Vertical permeability Skin factor Horizontal well position Horizontal well length Rate dependent skin coefficient (D) Boundary configuration distance : L NF Computed initial pressure Value 0.9301 bbl/psi 1.9738 bbl/psi 0.0500 hr 0.2568 md 8.6761 md -0.5551 0.5000 650.028 ft 0.00 1/(Mscf/day) 93.7633 ft 2503.9954 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION
Reservoir Description Fluid type : Condensate Well orientation : Horizontal Number of wells : 1 Number of layers : 1 Layer Parameters Data Formation thickness Average formation porosity Water saturation Gas saturation Formation compressibility Total system compressibility Layer pressure Temperature Well Parameters Data SMITH OIL COMPANY Layer 1 42.00 ft 0.075 0.30 0.70 5.4789e-6 psi-1 3.3060e-4 psi-1 2200.0000 203.0000 deg F Well radius Distance from observation to active well Wellbore storage coefficient Storage Amplitude Storage Constant Second Wellbore Storage Change for Second Storage Well offset - x direction Well offset - y direction Fluid Parameters Data Gas gravity Condensate gravity Condensate/Gas ratio Water-Gas ratio Water salinity Check Pressure Check Temperature Gas density Initial gas viscosity Gas formation volume factor Water density Water viscosity Water formation volume factor Initial Z-factor Initial Gas compressibility Water compressibility Well 1 0.25 ft 0.0000 ft 0.9301 bbl/psi 0.0000 psi 0.0000 hr 1.9738 bbl/psi 0.0500 hr 0.00 ft 0.00 ft Layer 1 0.7480 sp grav 54.6999 API 16.7350 STB/MMscf 128.9700 STB/MMscf 4.7750e4 ppm 2200.0000 203.0000 deg F 8.52495 lb/ft3 0.0170926 cp 7.1520e-3 ft3/scf 62.1749 lb/ft3 0.29849 cp 1.03661 RB/STB 0.83919 4.6324e-4 psi-1 2.8456e-6 psi-1 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION Page 1 of 8
Fluid Parameters Data (cont) Layer 1 Separator Pressure 195.0000 Separator Temperature 72.0000 deg F Vapourising volume ratio 1043.4100 scf/stb Wet stream gravity 0.7984 sp grav Wet stream rate multiplier 1.01746 Layer 1 Correlations Ug Correlation : Carr et al Vap Vol Correlation : Gold et al Layer Boundaries Data Layer 1 Boundary Type : Single fault L1 Boundary : No-flow L1 L2 L3 L4 Drainage area Dietz shape factor Layer 1 93.7633 ft 0.0000 ft 0.0000 ft 0.0000 ft 0.0000 acres 0.0000 Layer 1 Model Data Layer 1 Model Type : Two no-flow boundaries - homogeneous Permeability Skin factor (Well 1) Vertical permeability Horizontal well length Horizontal well position Rate dependent skin coefficient (D) RD1 EX3 Data Files 0.00000 1453.7500 0.01670 1458.1400 0.03340 1459.8800 0.05000 1460.5000 0.06670 1461.2700 0.08340 1462.2000 0.10000 1462.9700 0.11670 1463.7800 0.13340 1464.5000 0.15000 1465.1400 0.16670 1466.0601 Layer 1 0.2568 md -0.5551 8.6761 md 650.028 ft 0.5000 0.00 1/(Mscf/day) 0.18340 1466.5699 0.20000 1467.5000 0.21670 1467.9000 0.23340 1468.6300 0.25000 1468.9900 0.26670 1469.7500 0.28340 1470.0900 0.30000 1470.8300 0.31670 1471.7000 0.33340 1472.1400 0.35000 1472.4500 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION Page 2 of 8
0.36670 1473.3600 0.38340 1473.7900 0.40000 1474.3800 0.41670 1474.9700 0.43340 1475.1700 0.45000 1475.9700 0.46670 1476.1400 0.48340 1476.9800 0.50000 1477.1200 0.51670 1477.6700 0.53340 1478.1500 0.55000 1478.4399 0.56670 1478.8900 0.58340 1479.2700 0.60000 1479.5000 0.61670 1479.8500 0.63340 1480.2400 0.65000 1480.8900 0.66670 1481.5100 0.68340 1481.5400 0.70000 1481.8900 0.71670 1482.2000 0.73340 1483.0900 0.75000 1483.4301 0.76670 1483.4301 0.78340 1484.0200 0.80000 1484.3199 0.81670 1485.1300 0.83340 1485.0400 0.85000 1485.1500 0.86670 1485.5200 0.88340 1486.2700 0.90000 1486.8000 0.91670 1487.1400 0.93340 1487.7200 0.95000 1488.3600 0.96670 1488.8199 0.98340 1489.7800 1.00000 1489.8600 1.01670 1490.0800 1.03340 1490.6200 1.05000 1490.9399 1.06670 1491.4301 1.08340 1491.8400 1.10000 1492.5300 1.11670 1492.9000 1.13340 1493.5400 1.15000 1493.9500 1.18340 1494.6100 1.20000 1495.3101 1.21670 1495.7300 1.23340 1496.3700 1.25000 1496.5900 1.26670 1497.2300 1.28340 1497.6700 1.31670 1498.2800 1.33340 1499.0200 1.35000 1499.1801 1.36670 1499.9200 1.40000 1500.8000 1.41670 1501.1300 1.43340 1501.9600 1.46670 1502.1899 1.48340 1503.2100 1.50000 1503.2800 1.53340 1504.1801 1.55000 1504.3900 1.58340 1505.3400 1.60000 1505.4399 1.63340 1506.3101 1.65000 1506.9900 1.68340 1507.5601 1.70000 1508.1500 1.73340 1509.0500 1.75000 1509.3101 1.78340 1509.9500 1.81670 1511.1000 1.83340 1511.2700 1.86670 1512.0200 1.90000 1512.7500 1.93340 1513.6500 1.95000 1514.1700 1.98340 1514.7200 2.01670 1515.7600 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION Page 3 of 8
2.05000 1516.3199 2.08340 1517.4000 2.11670 1518.0200 2.15000 1518.9200 2.18340 1519.2800 2.21670 1520.1700 2.25000 1520.7300 2.28340 1521.5300 2.31670 1522.0000 2.35000 1522.9900 2.38340 1523.3800 2.43340 1524.0400 2.46670 1524.7500 2.50000 1525.0900 2.55000 1525.7300 2.58340 1526.2500 2.61670 1527.1400 2.66670 1527.7300 2.70000 1528.3500 2.75000 1528.6200 2.78340 1528.7300 2.83340 1529.4301 2.88340 1530.3900 2.91670 1530.9301 2.96670 1531.8800 3.01670 1533.4301 3.05000 1533.9000 3.10000 1533.9000 3.15000 1534.9600 3.20000 1535.6899 3.25000 1536.2900 3.30000 1536.9900 3.35000 1537.5100 3.40000 1538.0000 3.46670 1539.0100 3.51670 1539.3101 3.56670 1540.1801 3.61670 1540.4000 3.68340 1541.1600 3.73340 1541.9800 3.80000 1542.5699 3.85000 1542.9000 3.91670 1543.8000 3.96670 1544.4399 4.03340 1545.0400 4.10000 1545.3600 4.16670 1546.1700 4.21670 1547.0200 4.28340 1548.0800 4.35000 1548.9700 4.41670 1549.2500 4.50000 1550.4200 4.56670 1551.0000 4.63340 1551.6600 4.70000 1552.2200 4.78340 1552.8500 4.85000 1553.5500 4.93340 1554.2100 5.00000 1554.4500 5.08340 1555.2400 5.16670 1556.2100 5.23340 1556.4900 5.31670 1557.2400 5.40000 1558.0800 5.48340 1558.4100 5.56670 1559.0200 5.66670 1559.7800 5.75000 1560.8101 5.83340 1561.1100 5.93340 1561.7700 6.01670 1562.4200 6.11670 1563.4301 6.20000 1564.0400 6.30000 1564.7900 6.40000 1565.3000 6.50000 1565.9800 6.60000 1566.8600 6.70000 1567.4900 6.80000 1567.9399 6.91670 1569.0100 7.01670 1569.4100 7.13340 1570.2500 7.23340 1571.2400 7.35000 1571.8600 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION Page 4 of 8
7.46670 1572.4500 7.58340 1573.2100 7.70000 1574.1700 7.81670 1575.0500 7.93340 1575.7800 8.05000 1576.3700 8.18340 1577.2900 8.31670 1578.1200 8.43340 1578.9100 8.56670 1579.6600 8.70000 1580.4800 8.83340 1581.2900 8.96670 1582.0100 9.11670 1583.1100 9.25000 1583.9399 9.40000 1584.6400 9.53340 1585.3101 9.68340 1586.2600 9.83340 1586.9700 9.98340 1587.8700 10.15000 1588.7700 10.30000 1590.0500 10.46670 1590.9700 10.61670 1591.7600 10.78340 1592.4200 10.95000 1593.4700 11.13340 1594.5000 11.30000 1595.5300 11.46670 1596.5500 11.65000 1597.2400 11.83340 1598.6899 12.01670 1599.6500 12.20000 1600.3300 12.38340 1601.4399 12.58340 1602.7500 12.78340 1603.8300 12.96670 1604.7000 13.16670 1605.7000 13.38340 1606.8000 13.58340 1608.1100 13.80000 1609.0400 14.01670 1610.2100 14.23340 1611.4500 14.45000 1612.3800 14.66670 1613.8600 14.90000 1614.8500 15.13340 1615.9600 15.36670 1617.5200 15.60000 1618.3500 15.83340 1619.6899 16.08340 1620.8600 16.33340 1622.1899 16.58340 1623.6300 16.85000 1624.8300 17.10000 1626.2300 17.36670 1627.3500 17.63340 1628.8900 17.91670 1630.3199 18.18340 1631.6200 18.46670 1632.7500 18.75000 1634.3000 19.05000 1635.6600 19.33340 1637.2500 19.63340 1638.3900 19.95000 1639.9500 20.25000 1641.4200 20.56670 1642.7900 20.88340 1644.4900 21.20000 1645.8700 21.53340 1647.3500 21.86670 1649.1400 22.20000 1650.4000 22.55000 1652.1600 22.90000 1653.9700 23.25000 1655.2000 23.61670 1656.8700 23.98340 1658.5500 24.35000 1660.1801 24.73340 1662.1500 25.11670 1663.5400 25.50000 1665.3101 25.90000 1667.1000 26.30000 1668.6700 26.70000 1670.4700 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION Page 5 of 8
27.11670 1672.4000 27.53340 1673.9800 27.96670 1675.8101 28.40000 1677.5900 28.83340 1679.7400 29.28340 1681.2800 29.73340 1683.2400 30.18340 1685.2000 30.65000 1687.1500 31.13340 1688.8300 31.61670 1690.8600 32.10000 1692.8900 32.60000 1694.8500 33.10000 1696.7900 33.61670 1699.0601 34.13340 1701.0800 34.66670 1703.2100 35.20000 1704.9000 35.75000 1707.3400 36.30000 1709.4000 36.86670 1711.3300 37.43340 1713.5800 38.01670 1715.9600 38.60000 1717.9399 39.20000 1720.0500 39.80000 1722.1801 40.41670 1724.6200 41.05000 1727.0100 41.68340 1729.3300 42.31670 1731.4399 42.98340 1733.9000 43.65000 1736.1200 44.31670 1738.3300 45.00000 1740.8199 45.70000 1743.4100 46.40000 1745.6500 47.13340 1747.9200 47.85000 1750.6700 48.60000 1753.0000 49.35000 1755.6500 50.11670 1758.1500 50.88340 1760.4301 51.66670 1763.1801 52.46670 1765.4800 53.28340 1768.0900 54.11670 1770.7100 54.95000 1773.5000 55.80000 1776.1500 56.66670 1778.9500 57.53340 1781.6400 58.43340 1784.3500 59.33340 1786.6899 60.25000 1789.5699 61.18340 1792.1899 62.13340 1795.2000 63.08340 1798.0400 64.06670 1800.7800 65.05000 1803.4301 66.06670 1806.3500 67.08340 1809.2700 68.11670 1812.1899 69.16670 1815.2500 70.25000 1818.0500 71.33340 1821.0601 72.43340 1823.9200 73.55000 1827.1801 74.70000 1829.9500 75.85000 1833.1100 77.01670 1836.0000 78.21670 1839.2600 79.41670 1842.2100 80.65000 1845.4500 81.90000 1848.4700 83.16670 1851.8101 84.45000 1854.9000 85.76670 1858.1500 87.08340 1861.3900 88.43340 1864.5100 89.80000 1867.8101 91.20000 1870.8900 92.60000 1874.0400 94.03340 1877.2700 95.48340 1880.5300 96.96670 1884.1899 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION Page 6 of 8
98.46670 1887.4600 99.98340 1890.9200 101.53340 1894.3000 103.11670 1897.4100 104.70000 1901.0900 106.31670 1904.5200 107.96670 1907.9200 109.63340 1911.1300 111.33340 1914.6000 113.05000 1918.3000 114.80000 1921.5100 116.58340 1925.3400 118.38340 1928.7100 120.21670 1932.0200 122.08340 1935.9500 123.96670 1939.4301 125.88340 1943.0200 127.83339 1946.6200 129.81670 1950.2400 131.81670 1953.5699 133.85010 1957.3400 135.92090 1960.8199 138.02510 1964.3800 140.16270 1968.2500 142.31670 1971.9800 144.51671 1975.6801 146.76671 1979.3900 149.01671 1982.9000 151.31670 1986.8500 153.66672 1990.1700 156.06670 1994.2800 158.46671 1997.7000 160.91672 2001.6700 163.41672 2005.3800 165.91672 2008.7300 168.51671 2012.6500 171.11670 2016.5500 173.76671 2020.1100 176.46671 2023.8000 179.16672 2027.5400 181.96671 2031.1700 184.76671 2035.1700 187.61670 2038.8101 190.51671 2042.4399 193.46671 2046.2500 196.46671 2050.0601 199.51671 2053.8101 202.56670 2057.3101 205.71671 2061.1299 208.91672 2064.6799 212.11670 2068.4500 215.41672 2072.2700 218.76671 2075.6899 222.11670 2079.3101 225.56670 2083.1799 229.06670 2087.0500 232.61668 2090.3401 236.21672 2094.2700 239.86668 2097.6001 243.56670 2101.5701 247.31670 2104.9099 251.16672 2108.8701 255.06670 2112.2800 259.01672 2116.0500 263.01672 2119.3899 267.06671 2123.1299 271.21671 2126.2700 275.41672 2129.8799 279.66672 2133.4600 284.00000 2136.9700 288.40002 2140.6799 292.85004 2143.7900 297.38342 2147.6201 301.98340 2151.0400 306.65002 2154.2600 311.40002 2157.5901 316.21671 2160.9500 321.11670 2164.5601 326.08344 2167.7600 331.11670 2171.1699 336.25000 2174.4299 341.45001 2177.8601 346.73340 2181.1599 352.10004 2184.2500 ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION Page 7 of 8
357.53342 2187.4299 363.06671 2190.9199 368.68341 2194.1499 373.73340 2196.8501 373.75000 2196.8301 373.76672 2197.1399 Rate Change Data Pressure Rate MMscf/day -276.00000 0.0000 0.0000 0.00000 1453.7500 2.1390 373.76669 2197.1399 0.0000 SMITH OIL COMPANY ARC PRESSURE DATA, INC. - PERMIAN BASIN REGION Page 8 of 8