Video Camera Log Used for Water Isolation in the Main Body "B" Pool, Elk Hills Field, Kern Co., California-Water and Oil Identification

Abstract

The Main Body 'B' reservoir in the Elk Hills Field is a peripherally waterflooded, +400' thick series of layered, turbidite Stevens sands. Permeability variation between layers adversely affects the vertical sweep, resulting in production from lower permeability oil sands dominated by production from higher permeability sands. This paper discusses the unique use of various tools to identify water zones to isolate and oil zones to stimulate. Tools used to identify water and oil entry are discussed With respect to their capabilities of identifying oil and water entry into the well bore. Swept and unswept layers are identified and the confidence level to propose a water isolation remedial has been developed; The confidence level is based on the analysis of a video camera log, open hole logs, production logs and production tests. This analysis begins when a candidate well with a high water cut is shut in, and the afterflow is viewed with a video camera. Oil entry is identified and evidence of water entry is inferred. These observations are compared with results from production tests in offsets, electric logs showing processed layers In an offset redrill, and production logs, and a video camera log from the same well. Agreement in the data provides the confidence level regarding what zones to isolate as watered-out and what zones will produce economic oil rates after the remedial. If results from water isolation remedials are available, these results may also be reported. Introduction New tools are required to identify oil and water entry to propose economic water isolation remedials in high rate, high water cut wells. Specifically the tools must identify oil entry with a high level of certainty and detail. This level of certainty and detail is required in reservoirs that represent an economically risky environment with respect to water isolation remedials. Prior to using the video camera log, the primary tools available included offset production tests and production logs. Yet these conventional methods do not satisfy the degree of certainty required in this high risk environment. The Main Body 'B' reservoir at Elk Hills is characterized by heterogeneities between individual sand lobes and energy from a maturing, peripheral waterflood. These aspects create a challenging environment for water isolation due to 1) uncertainty of the injection water advancement by layer, 2) high reservoir pressure resulting in additional remedial costs, and 3) high reservoir pressure resulting in an increased likelihood of isolation failure due to high pressure differentials after the isolated layers undergo drawdown differentials. The performance of the Main Body 'B' reservoir indicates uneven flood front distributions, particularly with respect to vertical conformance. P. 383