Weijermans, Peter-Jan (Neptune Energy Netherlands B.V.) | Huibregtse, Paul (Tellures Consult) | Arts, Rob (Neptune Energy Netherlands B.V.) | Benedictus, Tjirk (Neptune Energy Netherlands B.V.) | De Jong, Mat (Neptune Energy Netherlands B.V.) | Hazebelt, Wouter (Neptune Energy Netherlands B.V.) | Vernain-Perriot, Veronique (Neptune Energy Netherlands B.V.) | Van der Most, Michiel (Neptune Energy Netherlands B.V.)
The E17a-A gas field, located offshore The Netherlands in the Southern North Sea, started production in 2009 from Upper Carboniferous sandstones, initially from three wells. Since early production history of the field, the p/z plot extrapolation has consistently shown an apparent Gas Initially In Place (GIIP) which was more than 50% higher than the volumetric GIIP mapped. The origin of the pressure support (e.g. aquifer support, much higher GIIP than mapped) and overall behavior of the field were poorly understood.
An integrated modeling study was carried out to better understand the dynamics of this complex field, evaluate infill potential and optimize recovery. An initial history matching attempt with a simulation model based on a legacy static model highlighted the limitations of existing interpretations in terms of in-place volumes and connectivity. The structural interpretation of the field was revisited and a novel facies modeling methodology was developed. 3D training images, constructed from reservoir analogue and outcrop data integrated with deterministic reservoir body mapping, allowed successful application of Multi Point Statistics techniques to generate plausible reservoir body geometry, dimensions and connectivity.
Following a series of static-dynamic iterations, a satisfying history match was achieved which matches observed reservoir pressure data, flowing wellhead pressure data, water influx trends in the wells and RFT pressure profiles of two more recent production wells. The new facies modeling methodology, using outcrop analogue data as deterministic input, and a revised seismic interpretation were key improvements to the static model. Apart from resolving the magnitude of GIIP and aquifer pressure support, the reservoir characterization and simulation study provided valuable insights into the overall dynamics of the field – e.g. crossflows between compartments, water encroachment patterns and vertical communication. Based on the model a promising infill target was identified at an up-dip location in the west of the field which looked favorable in terms of increasing production and optimizing recovery. At the time of writing, the new well has just been drilled. Preliminary logging results of the well will be briefly discussed and compared to pre-drill predictions based on the results of the integrated reservoir characterization and simulation study.
The new facies modeling methodology presented is in principle applicable to a number of Carboniferous gas fields in the Southern North Sea. Application of this method can lead to improved understanding and optimized recovery. In addition, this case study demonstrates how truly integrated reservoir characterization and simulation can lead to a revision of an existing view of a field, improve understanding and unlock hidden potential.
Singh, Kumar Abhishek (School of Petroleum Technology, Pandit Deendayal Petroleum University) | Sarkar, Prakhar (School of Petroleum Technology, Pandit Deendayal Petroleum University) | Praleya, Pranshu (School of Petroleum Technology, Pandit Deendayal Petroleum University) | Sai, Gogineni Sudarsan (School of Petroleum Technology, Pandit Deendayal Petroleum University)
The downtime of oil and gas industry dictates the review of Vortex Technology that has been used oil and gas industry for many intentions. An innovative application of this technology is in conjunction with gas lifts that not only organise the three phase flow of oil, gas and water but also optimize production. We can rather say that this technology has the potential to produce unconventional completions. The application of downhole cyclone boosted production many folds. The application of downhole cyclone presented an interesting idea for production optimization in gas lifts and well intervention schemes. The versatile nature of tool dictates its application in CTU and horizontal wells as flow control devices. The downhole cyclone will certainly provide a way forward to cut risks in offshore projects. Therefore, this innovation is certainly a permanent solution to all problems.
Bluebell Field oil production is unconventional in that fractures provide the preponderance of the storage capacity and the fluid pathways in this tight sand/carbonate reservoir. Identifying fracture density away from existing well control would allow a drainage area to be mapped and would aid in determining the well spacing needed to effectively drain remaining hydrocarbon reserves in Bluebell Field. An added benefit of identifying natural fractures is the possibility of uncovering additional new drilling opportunities in zones not previously considered as targets and thus adding new reserves.
A 35 square mile wide azimuth 3D seismic program was conducted in 2010–2011 over a portion of Bluebell Field. One of the goals, based on the seismic data, was to locate areas of high fracture intensity in the productive Eocene Green River Formation to Paleocene Wasatch Formation interval and to match that against cumulative fluid production to find under-drained areas for future well locations. Post-stack multi-attribute statistical analysis was conducted over three reservoir intervals in the Wasatch interval since the Wasatch had produced over 80 percent of the cumulative production. The analysis consisted of seismic attribute selection and optimization by step-wise multivariate linear regression using cross-validation techniques which included hidden well prediction. After extensive analysis of over 300 attribute maps, a combination of seven seismic attributes was eventually chosen for the statistical modelling and comparison with production data. The resultant map of predicted fracture network was then correlated with cumulative fluid production from the first Wasatch well in each section. Best results (0.842 correlation coefficient) were obtained over one of the three modeled reservoir intervals. This reservoir interval, approximately 700 feet thick, correlates with the ‘most prolific oil-producing zone’ (geologic marker W180-WAS200) that had been identified from previous geologic work.
Practical application of this technique along with offsetting well drainage patterns has enabled Devon Energy to high grade future drilling locations.
Fracture conductivity in many hydraulic-fracturing treatments can be inadequate. It is greatly affected by the concentration of the packed proppant in the fracture. Higher concentrations yield higher conductivity by virtue of a wider fracture. However, there are practical limitations to the amount of proppant that can be placed into any particular reservoir, and therefore production is often conductivity limited.
An alternate approach to achieve high conductivity is to create a fracture by placing well-distributed, low-density particles characterized by a proppant concentration less than 0.1 lbm/ft2. Low particle concentrations result in fractures that have high porosity and are fundamentally different from fractures with packed beds of conventional proppants.
In this paper, the theoretical basis for the conductivity of these fractures is presented. A 3-D model has been developed to simulate high-porosity fractures created with these particles. Test data used to refine the model can be used to predict the conductivity of the fracture based on the porosity level, the closure stress, and the material properties.
Production data from two application areas in North America are shown to highlight the benefits of using this type of fracturing proppant.
A screening life cycle analysis (LCA) is included to evaluate and highlight the beneficial attributes of using a low-density proppant to achieve fractures with high conductivity. The LCA considers the impact of logistics and fracture design on the environment.