A heterocyclic cyclopentadienyl analog containing only one carbon atom in the ring was prepared and a polymeric lithiocene and a monomeric zincocene containing this novel ligand have been isolated and crystallographically characterized.

With the recent proliferation of horizontal drilling specifically targeting oil-bearing reservoirs, high-strength-acid-fracturing treatments in the Beaverhill Lake formation in northern Alberta have increased dramatically in both product volume and number of treatments. The Beaverhill Lake formation is a limestone/calcareous shale that produces a desirable mid- to high-API sweet crude oil. Although the crude oil typically has a low concentration of asphaltenes, the oil is sensitive to acid and/or iron-induced asphaltene precipitation. As the acid strength increases and ferric iron is dissolved into solution, it becomes increasingly difficult to chemically prevent the asphaltenes from precipitating. Acid blends designed to prevent asphaltene precipitation also tend to be emulsifying with the crude oil; therefore, a careful balance between antisludge additives and nonemulsifiers must be found. The objective of this study is to compare anionic and cationic antisludge agents, and to determine if there was an observable benefit in production when using a specific type of antisludge agent in the Beaverhill Lake formation.

Many studies have been performed to identify chemical additives that will aid shale stability in large volume slick water fracturing treatments. Most of the targeted shale formations have a very low permeability, do not experience conventional leakoff and do not contain high amounts of swelling clays such as smectite, leading to a perception that the shale is not water sensitive. However, recent laboratory evaluations have shown that not all shales are stable in fresh water, destabilizing with fresh water contact and releasing fines which could potentially result in formation damage and reduce net fracture pack conductivity.Previous studies of the ability of inorganic salts, temporary clay stabilizers, and permanent polymeric based clay stabilizers show that some of the common hydraulically fractured shales encounter stability problems when contacting fresh water. The studies have revealed that cationic polymeric permanent clay stabilizers improve the stability of the water sensitive shales. However, polymeric shale stabilizers are not without potential detriments. Polymers can lead to formation damage by blocking pore throats and reducing permeability. Additionally, the use of cationic polymers can limit the use of other chemical compounds used in treating fluids that may not be compatible with the cationic charge. This paper will compare a non-polymeric permanent clay stabilizer to conventional cationic polymers, temporary clay stabilizers, and inorganic salts and demonstrate equivalent and, sometimes, improved performance. Laboratory data from shale stability (roller oven), capillary suction time (CST), and regained permeability (core flow) studies will be presented demonstrating the efficacy of this new compound. Shales selected for the study will include standard Pierre shale and a variety of commonly hydraulically fractured shales from North America. Additionally, chemical compatibility testing will demonstrate the benefits of the new compound over conventional cationic polymeric clay stabilizers.

Calcium sulfate in the form of gypsum (CaSO4.2H2O) and anhydrite (CaSO4) is one of the most prevalent evaporite minerals typically found in the prolific middle Devonian carbonate rocks of the Western Canadian Sedimentary Basin (WCSB). Strong mineral acids, in particular hydrochloric acid (HCl), are employed to enhance permeability in the near wellbore area of the oil wells in these carbonate-bearing formations during matrix stimulation and hydraulic fracturing treatments. When calcium sulfate (CaSO4) comes in contact with the live acid, partial dissolution can occur. As the acid solution is progressively spent inside the carbonate rock, the concentration of unassociated calcium ions will increase. These ions will become readily available to react with the sulfate ions in the neutralized solution and cause, the unavoidable re-precipitation of CaSO4 crystals in the pore throat, therefore severely plugging the newly created flow channels. Based on Le Chatelier's principle and the common ion effect, the addition of a soluble calcium salt to the treating acid package has been an economical oil field practice established to suppress the initial dissolution of CaSO4. However, a secondary protection mechanism is still required because sulfate-rich connate water could commingle with the spent acid solution during swabbing and/or flowback operations, reaching the ideal conditions for CaSO4 precipitation. To date, most of the CaSO4 scale inhibitors that have been applied for acid treatments relied on either the retardation of CaSO4 crystal growth, or the creation of soluble complex salts with the calcium ions. This paper intends to detail the development and laboratory testing of a broad spectrum scale inhibitor specially formulated for high salinity and acid solutions that not only prevents the precipitation of CaSO4, but also helps to inhibit the initial dissolution of CaSO4. Introduction Covering a vast extension of 1.4 million square kilometers (Bowers 1997), The WCSB defines its coordinates between the southwestern border of the Canadian shield in Manitoba and the eastern flank of the Canadian Rocky Mountain system in British Columbia. Within the WCSB, approximately half is composed of carbonate reservoirs of the Devonian age. These Carbonate formations combine for a project reserve of 15 billion barrels of oil and 35 trillion cubic feet of natural gas (Li 2002). These important reserves of hydrocarbons have been successfully exploited since the late 1940's (Milligan 1998).

Slick water hydraulic fracturing treatments are the preferred method for stimulation of tight hydrocarbon plays as these treatments enhance the complexity of fracture networks, increase fracture lengths, reduce formation damage and decrease treatment costs. These characteristics of a slick water treatment are critical to produce economic wells in unconventional formations. Even though these treatments are effective, they also have disadvantages that can limit production and increase treatment costs. With slight modifications to the treatment design of traditional slick waters-the addition of a novel chemical and 5% nitrogen-the limitations can be reduced.