Overcoming the Typical Operational Problems & Cost of Water Injection Using Dumpflooding

Abstract

Meleiha North East oil Field is located in the Egyptian Western Desert. Its estimated value for the OIIP is 125.5 MMSTBO. The field started production in the year 1986 and was subjected to 4 years of natural depletion. The reservoir mainly consists of three producing layers; all are heterogeneous with local poor horizontal connectivity and low natural pressure support. Consequently, and during that period of natural depletion, the recovery of only 14.7 MMSTBO caused the reservoir pressure to decline from an initial value of 2300 Psi to 1000 Psi; a slope of approximately (-325 Psi/year). After applying water-injection in the year 1990, the pressure decline-slope got reduced to (-30 Psi/year). Currently the field contains 27 producers and 3 injectors. The distance to the nearest water-source well is approximately 10 Kilometers. Maintaining continuous injection remained a challenge due to the typically associated operational problems; the long length of the injection lines increased the frequency of line leakage, corrosion, and blockage. Both water-source and injection wells require regular maintenance operations to handle problems such as casing leaks and ESP's maintenance. The necessity of flushing the injection lines after each operation results in additional time losses. Other problems maybe related to issues with the injection plant. All of these operational difficulties eventually affect the reservoir pressure performance and consequently decrease the production performance. As an attempt to improve the performance of water injection, a dump-flood project was initiated. The idea is based on using the pressure differential between the perforated intervals within a single well to drive the water coming from a relatively high pressure water-bearing zone to a lower-pressure oil-bearing zone(s). Well NE-41 was initially drilled as water injector. The RFT measurements indicated that the pressure in three oil bearing zones (B-I, III & IV) averaged around 400 Psi, while the pressure in a water-bearing zone (B-VI) was found to be 2250 Psi. Hence, the well was selected to be a pilot for dumpflooding. After completing the well as planned, a PLT was performed and its results indicated that the water-bearing zone produced 1100 BWPD that were distributed among the three recipient zones. The project therefore was considered successful for the following reasons: Avoiding all the typical operational problems such as surface leakages, casing leakages, and ESP's maintenance,Providing a minimum cost for supplying the reservoir pressure by water injection.

Evaluation of Double Displacement Process via Water and Gas Dumpflood

“…Helaly et al [12] initiated a water dumpflood project to slow down reservoir pressure decline which replaced from conventional water injection due to some operational problems caused by lengthy injection (the oil field is approximately 10 kilometer away from water-source). Problems such as line leakage, corrosion and blockage required regular maintenance.…”