Abstract
During the completion operations of High pressure (HP) wells the perforated pay zone may require acid stimulation to remove and clean up debris and therefore permit unrestricted hydrocarbon flow. Also later in the well life, carbonate scale may deposit that can restrict the wellbore thus limiting production this is normally removed with the aid of a scale dissolver treatment(s). These chemicals can be very corrosive towards well construction materials. Hence the need to assess acid stimulation and scale dissolver chemical packages to prevent severe corrosion damage to the wells tubular sand equipment. For this reason, laboratory testing of these chemical packages plays an important role. However, it has been observed that the experimental parameters can heavily influence the results. In particular, it has been shown that critical parameters like the pressure, solution volume/test specimen area ratio, temperature ramp up and cooling times as well as post-test specimen treatment are key to achieving reliable test results. Also it is important not only to choose the correct test parameters but also to scrutinize the test set-up such that it replicates the treatment application as closely as possible. Once established the test procedure needs to be detailed to allow inter-laboratory testing replication. With this purpose in mind a testing program was designed using high strength martensitic and duplex stainless steels, namely, UNS S41426, 17CR (17Cr-4Ni-2.5Mo-1Cu) and UNS S39274. A round robin testing program was carried out between two laboratories using a 15% HCl based scale dissolver package at 110°C. The results underlined the importance of proper alignment of test parameters between laboratories and eventually led to acceptable agreement between the laboratories results.
