Separate Production Techniques for Multiple Zones in Daqing Oil Field
Authors: Wang Demin , Chen Chaoyin 
Published: December 2007

Daqing oil field is a heterogeneous multizone sandstone reservoir. It had serious water channeling and zonal interference troubles; therefore, a set of single-tubing separate zone production techniques including separate zone injection, separate zone production, separate zone stimulation, and production logging, were developed and used successfully in the oil field.

Introduction

Daqing oil field has been developed for 21 years. Because this oil field is very large and the edge water is relatively inactive, early internal injection of water (at the same time the oil field was put on production) was practiced to maintain the pressure of the reservoir at its practiced to maintain the pressure of the reservoir at its original level. However, there are more than 40 separate zones in this reservoir, the viscosity of the crude oil in the reservoir is 0. 05 to 0. 10 Pas (5 to 10 cp), and there is considerable difference between the permeability of different zones and of different parts and different directions in a single zone. When a well is produced, the fewer separate zones it is divided into the higher the diversity factor (which is the thickness-weighted mean of the permeability variance of the zones) (Fig. 1). Water channeled in the high-permeability layers. To cope with these problems, separate zone production techniques are used. In these 21 years, Daqing oil field has used an entire set of separate-zone production techniques applicable to multizone sandstone reservoirs of medium depth, including water injection, production, stimulation. and production logging techniques. production logging techniques. Separate-Zone Water-Injection Techniques

Since early water injection was started, the reservoir pressure was maintained, and oil wells had a high pressure was maintained, and oil wells had a high flowing potential. However, new problems came up: water channeled to an oil well 250 m (820 ft) from the injector a few months after water injection was started in a pilot-test area of the oil field. After 3 years of indiscriminate pilot-test area of the oil field. After 3 years of indiscriminate injection into all zones of the central section [an area of 146 km2 (56 sq miles)] of Sartu oil field (Daqing) 60 % of the producers, at the first row (a staggered line drive is used here) already had a water cut. Also, the water cut increase per production of 1 % of original oil in place (OOIP) was 6 to 7%, but the recovery was only 5% at that time. To reduce the water-increase rate and to obtain a more evenly distributed water-injection profile, several separate-zone water-injection techniques were used in the field. The main tools of these techniques are packers and water-injection mandrels. Inflatable packers were developed first. These packers give reliable performances and are highly adaptable [OD of the packer is 110 mm (4 in. ), and they can be used in casing with a range of 118 to 132 mm (4. 6 to 5. 2 in. ) ID]. Any time after water injection is stopped, water can be circulated down the annulus and up the tubing; the packers are of simple construction and are easy to run in packers are of simple construction and are easy to run in and out of the hole. Since 1963, they have been used extensively in the oil field. A weak point is that packers require a differential pressure of 600 to 800 kPa (87 to 116 psi) between the tubing and annulus to maintain psi) between the tubing and annulus to maintain inflation. To conserve energy and to diminish this differential pressure, hydraulic compression packers were pressure, hydraulic compression packers were developed. No differential pressure is needed to keep this type of packer in a compressed state.

JPT

P. 1521