Perforating Resin-Consolidated Zones for Capacity Improvement

Abstract

Sand control using epoxy resin consolidation usually is effective, but treated wells fail to produce occasionally. This, paper presents field results showing that through-tubing jet reperforation of wells into the previously resin-consolidated zone can restore production. previously resin-consolidated zone can restore production. Laboratory tests indicated clean, productive perforations and undamaged resin consolidation. Introduction Reservoirs from surface to 8,000 ft and deeper off the Louisiana coast are notorious sand producers. Excessive sand production can result in separation and disposal problems, erode pipe and equipment, damage casing, problems, erode pipe and equipment, damage casing, and shutdown pumps. Sand control is necessary in wells of this type. From 1958 to 1972, when multiple completions were most common, Chevron Oil Co. elected to complete many wells dually with two-stage gravel packs in lower zones and resin consolidation in upper zones. Any selective (single) zones also were resin consolidated. Both sand control methods have proven highly successful. However, in several instances some resin-consolidated zones failed to produce, and acidizing also failed to induce flow. Assuming sand or mud fillup is not blocking the perforations, it has been proposed that unintended dirt or debris injected with the resin and associated fluids may plug perforations or damage near-well formation plug perforations or damage near-well formation permeability. permeability.After all other methods failed to induce flow from these wells, reperforation with through-tubing, jet-perforating guns gave promising results. Field Work Six nonproducing or low-production resin-consolidated wells were reperforated. Two other selected wells were not reperforated because of mechanical problems encountered. The selected wells are located east of the Mississippi River delta in the Main Pass area. The productive section is Upper Miocene in age, with sands and productive section is Upper Miocene in age, with sands and shales deposited in a near-shore marine environment. As the electric logs (Fig. 1) suggest, some sands are massive and relatively clean with porosities of 30 to 35 percent, while others are argillaceous with lower porosity. The eight wells represented two different types of completion. One was the selective zone completion (Fig. 2). Casing was perforated, sand was resin consolidated and packers were placed on single tubing string, isolating the zones at initial completion. Only one zone was produced at a time, starting at the bottom and progressing up produced at a time, starting at the bottom and progressing up the tubing. When moving to an upper selective zone, lower zones were plugged off and a special tubing perforator was used to open the tubing between the packers perforator was used to open the tubing between the packers isolating the selective zone to permit flow. In contrast, when using the reperforation completion technique, the reperforating gun in a selective zone must perforate both tubing and casing. A through-tubing, expendable, capsule-type, jet perforating gun was used. Shot density was four shots per foot, oriented at a 90 degrees angle. Wells 1 and 2 were selective zone completions. The second type was the standard dual completion (Fig. 3). Two strings of tubing allowed simultaneous but separate production from both zones. In our examples, only the upper zone was resin consolidated. To reperforate these zones, the perforating gun was lowered through the short tubing string until it hung free in the upper zone. Only the casing was penetrated. JPT P. 283