The Determination Of Oil In Place After Waterflood In A Slightly Consolidated California Sandstone Reservoir
Authors: Weinbrandt R.M. 
Published: December 2007

Aminoil USA is conducting a pilot test of an alkaline flooding process in the Lower Main Zone of the Huntington Beach Field. The area where the alkaline flood is being pilot tested was originally drilled in 1940 and produced by primary means until 1969, at produced by primary means until 1969, at which time a pilot waterflood was initiated in Fault Block 22 using a single normal five-spot pattern. Approximately two pore volumes of water have been injected into the 17,000 ac.ft. project area and it is currently producing at a water-oil ratio of over 20. The same fault block and pattern where the waterflood was pilot tested is being used for the alkaline flood pilot program.

This paper presents the results of the reservoir definition work which preceded this pilot test. The principal objectives of the pilot test. The principal objectives of the reservoir definition work were to determine the amount and distribution of oil at a location in the pilot area that had been extensively waterflooded.

The engineering techniques used to satisfy the project objectives were: analysis of conventional, plastic sleeve and pressure cores; well logs; and analysis of past pilot area performance. Use of multiple evaluation methods has provided a check on the absolute accuracy of the parameter determination which would not be possible with a single method approach.

The determination of oil in place after waterflood will be used to evaluate the recovery efficiency of the waterflood and as a base from which to evaluate the recovery efficiency of the alkaline flood pilot test.

Introduction

The Huntington Beach Field is a major oil accumulation lying on the California coastline approximately 20 miles southeast of Los Angeles. Figure I shows the location of the Huntington Beach Field in the Los Angeles Basin with the offshore area of the field cross-hatched.

The field has a length of seven miles along the Newport-Inglewood Fault Zone and a maximum width of three miles. The trapping of oil is controlled by a complex combination of structural, fault, and stratigraphic mechanisms. Production from the offshore area is from five major zones with the upper zone assisted by steam injection while three of the lower zones are under waterflood. One of the lower zones has not yet been waterflooded and is producing on primary. The current water injection rate of 450,000 B/D ranks the Huntington Beach Field as the third largest waterflood in the U.S.

The offshore area of the Huntington Beach Field is shown in Figure 2. Note the change in orientation of this figure. All maps of the offshore area are oriented with the shoreline at the bottom, looking offshore. Contours are on the top of the Lower Main Zone with the alkaline flood project area outlined near the center of the map.

The cross section A-B indicated on the Huntington Beach Offshore Area map (Fig. 2) is shown in Fig 3. This cross section is just offshore from the project area and shows the five major productive zones. The Lower Main Zone is the deepest productive zone and is the contoured horizon in Fig. 2. The Lower Main Zone is the subject of this evaluation and it is the zone where the alkaline flood will be pilot tested.