An Integrated Evaluation Workflow in Volcanic Reservoir with Comprehensive New Logging Data Sets A Case Study from Junggar Basin Xinjiang Oilfield China

Abstract This paper is to show a case study from Junggar Basin in North West China, which integrates a variety of logging data acquired by latest wireline measurements to analyze and evaluate lithology, pore types, fluid types and geomechanics properties of volcanic reservoir. Interpretation of volcanic reservoir has always been a great challenge. Recently, a lot more advanced data sets are available from the new wireline tools and measurements in Xinjiang Oilfield, such as SonicScanner, LithoScanner, Images logs, and latest 3D Saturn Radial probe forvolcanicformation sampling. The new data provide a better view for avolcanic reservoir. An integrated evaluation workflow that combines multiple latest wirelinetechnologies has been set, which can provide a good solution to the evaluation of volcanic reservoir in this area. Calibrating high precision and high-resolution lithology data to core data can accurately describe the complex lithology of volcanic reservoir. Meanwhile, apart from fractures identification, we are not only be able to categorize rock type with help of structure analysis provided by image data, but also can analyze the volcanic eruptible period by comparing images of adjacent wells. In addition, by acquiring, processing and interpreting advanced sonic scanner data; we can evaluate formation anisotropy, fracture effectiveness, identify gas zones and calculate geomechanics parameters, which will be used later during stimulation. In the end, utilizing the 3D Radial probes, the formation tester can confirm the fluid type by the downhole analyzer and actual fluid samples, this greatly reduce the uncertainly for evaluation and later stimulation. In this example, Well A from XinJiang oilfield, JinLong Block, is a typical volcanic formation which is characterized by highly developed natural fractures with various attitudes, complex lithology, which mainly contains andesitic volcanic breccia, breccia andesite, basalt, andesite, tuff and volcanic sedimentary rock, and quite low matrix permeability. Thus, SonicScanner, LithoScanner and FMI data have been acquired, and the favorable lithology, well-developed fracture zones, and high matrix porosity zones have been identified, the "sweet spot" have been located. In the end, the actual gas sample has been obtained for the first time by formation testers using 3D radial probe in volcanic reservoir in CHINA. This case study is a good example of volcanic reservoir evaluation. A workflow that is applicable to this area has been formed, which can be used as guidance for evaluation of other similar wells in the future.