Environmental legislation has significantly reduced the variety of scale inhibitor chemistries that can be used to prevent inorganic scale formation during the production and separation of crude oil from produced water. Poor ecotoxicity has severely impeded the use of phosphonates, while many polymers, the other traditional approach to scale control, fail to meet minimum biodegradation requirements.We have developed biopolymers based on synthetic/natural polymer hybrids that show enhanced biodegradation, are environmentally benign and are much less reliant on non-renewable monomer feedstocks than classical polymer scale inhibitors. As well as being more sustainable, this novel technology allows the inclusion of a broad range of functional groups that can be designed to meet the varying technical demands of oilfield scale inhibitor application environments.Various hybrid polymers have shown excellent performance under standard oilfield performance testing conditions versus a range of currently used chemistries. Some distinct benefits of hybrid technologies pertaining to oilfield scale control will also be expanded upon.
Cement retarders available in the market include the traditional lignosulfonates and synthetic copolymers. Commonly, lignosulfonates lack batch to batch reproducibility which hinders formulation consistency. Both lignosulfonates and synthetic polymers will retard the set of cement. However, their chemistry dictates that they also slow down setting time which increases waiting on cement time, thus increasing rig costs. This paper proposes a new smart cement retarder that overcomes these traditional negatives.
A number of polymers were designed and synthesized aiming for a chemical able to retard the set of cement while also acting as an accelerator once the cement slurry was in place. These polymers were tested for cement retardation performance using a high-pressure high-temperature (HPHT) consistometer. Static Gel Strength Analyzers (SGSA) measurements were used to determine compressive strength development as well as static gel strength development while curing under downhole temperature and pressure conditions.
The new smart cement retarder delivers cement retardation in the 125 - 350°F temperature range and can be used at higher temperatures using a co-retarder. This unique material delivers an accelerated set and attains 500 psi compressive strength very quickly which minimizes waiting on cement time. In addition, this new retarder builds static gel strength rapidly and minimizes gel transition time. Upscaling to field application, the top of the cementing column takes the longest to set. By having this inbuilt accelerator into the system, it allows the top of the column to set as fast as possible gaining the needed compressive strength at the weakest point of the cement column. This should ensure the quality of the cement job in comparison with conventional retarders with significant operating cost savings.
The new smart cement retarder will simplify cementing formulations due to its flexibility in dosage range of the retarder within the slurry and improve the quality of the cement jobs. As a result, the proposed smart cement retarder can help with minimizing risk of failures during production and possibly improving safety.
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