Well Spacing Case Study

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Figure 1: Micro-seismic data corroborating with Fiber Optic Interference Data

When dealing with hydraulically fractured wells and highly dense well spacing it is key to understand what is the proper well spacing to use for full field development. Operators space wells differently with little guidance from data which could lead to over investing or leaving reserves behind. The Z-System® will acquire data to tackle field development questions such as well spacing by providing an in-depth data set that will describe well to well communication.

In this case study, distributed fiber optics (DFO) was acquired in three of the eight wells on a Chevron pad. In addition, there was a robust formation evaluation that was performed including vertical and lateral logging suites, micro-seismic, conventional core and sidewall core to do a statistical study on well interference. The main objective was to determine whether the current well spacing was efficient.

The orange and yellow dots on Figure 1 indicate the micro-seismic data whereas the bars graph on the well indicate the DFO acoustical response. Using Figure 1 a direct correlation between fractured rock seen in micro seismic data and high productivity zones seen with DFO technology is present. The green markers show high intensity of interference near the heel and lower interference near the toe of the well. Looking at the yellow and orange dots in figure one, the microcosmic indicates high and low connectivity in the same zones.

Figure 2 shows an acoustical differential plot that depicts the high and low intensity zones. This data will allow for a client to understand interference between two wells at a cluster level.

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Figure 2: Acoustic data showing interference between wells

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Figure 3: Well thieving between well A and B

Figure 3 shows that the heel is very well connected while the rest of the well is moderately connected. As seen in Figure 3, the production profile when well B is turned off is a more intense picture assuring the operator that their wells are to closely spaced.

It can be concluded that thieving from well to well was apparent. The client adjusted there well spacing from 8 to 6 wells per pad and saw little to no production declines. With overwhelming evidence that the wells were to closely spaced Chevron could make an informative decision to cut costs without sacrificing production. As a result, a decision to drop from 8 wells per pad to 6 wells per pad was reinforced to reduce cost and maximize hydrocarbon recovery.