Schlumberger and four Eagle Ford Shale Play operators drilling in South Texas joined a consortium initiative to acquire various types of open hole logging data in several horizontal wells, and use the data to design the completions with optimum fracture stage and perforation cluster positioning. Horizontal production logs were subsequently used to gauge the effectiveness of using the log data to engineer the completions. This paper outlines the data acquisition techniques, analyses made on that data, application, results and conclusion.

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Data and preliminary results are presented from two vertical seismic profiles (VSPs) performed first in an open well and subsequently after the well was cased. Correlation between the VSPs and a seismic line recorded at a distance of 2 184 ft from the well are examined. Field results indicated that recorded waveforms were degraded in intervals of the well where cement bonding was poor, as might be expected. Analysis of the data revealed tube waves present in the cased‐hole VSP.

Open hole logging of highly deviated and horizontal wells is now becoming more accepted due to a recently developed conveyance and acquisition system that can greatly reduce the cost and risk associated with running logs in these types of wells. Conventional log measurements including resistivity and porosity, which in many cases may not have been previously economical to obtain in lateral wells, can now be used to delineate the needed basic reservoir properties for planning completions and future drilling designs.The method employs a newly engineered ultra slim toolstring that is designed to pass through the drill pipe and a specially designed hollow PDC bit into open hole. Data can then be obtained beyond the bit in memory while tripping out with the tools on pipe. Lost in hole risk and the higher cost of using other more expensive methods, such as LWD, can be minimized by using the drill pipe and bit to safely acquire the data and retrieve the tools if necessary. Circulation of the well fluids and pressure control can still be maintained throughout this process. A brief overview of the conveyance method and acquisition tools will be presented along with log examples from some of the common unconventional plays that outline the applications of this data.

In recent years, the number of horizontal wells drilled in the Permian basin of West Texas has increased. The Wolfcamp Shale is a prime target for horizontal well drilling because of its high liquids potential, which makes it an economically viable play. Ensuring maximum reservoir contact and successful hydraulic fracturing can be challenging in the Wolfcamp Shale, which is known for its highly heterogenous nature, high clay content, and high in situ stress.In the past, Clayton Williams Energy has had limited success stimulating its horizontal wells in the Wolfcamp Shale. These issues can be partially attributed to the highly stressed, laminated and heterogeneous nature of the formation. The conventional geometrically spaced perforation program that is typically selected when log data is not available or is not considered in the engineering design process can result in high pressure differentials between perforation clusters within a stage. The consequence of this includes reduced reservoir contact, incomplete proppant placement, screenouts, and skipped stages in parts of the lateral that are landed in higher stressed rock.In this study, openhole logging services acquired data through a specialized drill bit. These measurements were then integrated in an engineered staging and perforating workflow. The raw log data was processed to provide both petrophysical and geomechanical rock properties, which were used as inputs to quantify reservoir quality (RQ) and completion quality (CQ) for the engineered completion workflow. The workflow intelligently locates fracture stages and perforations by placing perforation clusters within a given stage in similar stressed rock as opposed to conventional geometric staging, which uniformly spaces out perforation clusters without accounting for the variability in rock properties along the lateral. The workflow honors the desired cluster spacing as much as the stress heterogeneity will allow. This optimization workflow was applied to a number of horizontal wells in the Wolfcamp formation of the Delaware basin in West Texas.The successful application of log measurements in the lateral for an engineered completion workflow resulted in the first stimulation treatment being placed 100% as designed with no issues. Three wells with log measurements where the engineered completion workflow was implemented showed, on average, a 67% increase in 90 days cumulative barrels of oil equivalent per lateral length compared to three geometric wells in the same area. A 28% increase in designed sand volume was pumped, and the operator also realized a 33% increase in successful stages, where more than 75% of the designed sand volume was pumped. The engineered completion workflow presented below describes a process that is meant to increase the effectiveness of stimulation treatments in horizontal well completions by increasing the percentage of perforation clusters that are stimulated and contributing to production.A 3D multiwell reservoir model was also designed using well log information from vertic...