Decoding the Water Flooding Processes from Produced Water Composition – A Case Study from the Halfdan Chalk Oil Field, Danish North Sea

Oil production monitoring and optimization from produced water analytics; a case study from the Halfdan chalk oil field, Danish North Sea

“…4) present in the Halfdan field occur in different parts of the field. The FW3 type is present on the southern flank of the field towards the Dan field and is clearly related to the presence of salt dome water (Schovsbo et al 2017) whereas the low salinity type (FW2) appear to be local end-member in the compositional continuum that extends north to the Valdemar/Roar fields. Within the Halfdan field, this suggests that local gradients in compositions exist and that each well location will represent a mix of the formation water produced along the long horizontal well track in contrast to all wells having same discrete compositions.…”

“…Average compositions of these local end-members (c.f. Schovsbo et al 2017) are presented in Table 1 and include a Formation Water 2 (FW2) that is characterised by medium to low salinities and medium high Ba 2+ concentrations and a Formation Water 3 (FW3) that is characterised by high Ca 2+ and medium high salinities and medium to low SO4 2concentrations (Fig. 3A).…”

“…Back flow of these injected chemicals is expected to affect the chemical composition of the produced water. "Process water", typically occurring within the first few years of production, is especially affected (Schovsbo et al 2017).…”

“…As the fields have matured, the volume of water to be handled has increased dramatically with a consequently high demand of energy needed for handling these large volumes, which may exceed 90% for some fields. Apart from being a waste product the produced water carries important information on reservoir dynamics and recovery processes (Schovsbo et al 2016(Schovsbo et al , 2017. The produced water can originate from natural water zones in the reservoir or from the water injection water, and its origin and relationship to oil and gas recovery is important for any field development, production monitoring and history matching.…”

Classification of and changes within formation water types in Danish North Sea Chalk: A study of the Halfdan, Dan, Kraka and Valdemar oil reservoirs

“…Thus, the composition of produced water is known to vary between different fields but also within the same field, which reflects the complex interplay of processes. [2,8,9,10,11,12] Despite this, relatively little work has been done to map these differences. The reported research have mainly focused on the mapping of the Cl − concentration as this ion is considered a relatively inert ion, which is measurably diluted upon seawater injection, as the formation water is typically characterized by significantly higher total salinity.…”