The paper describes laboratory development and field application of polymer-stabilized foams for gas-control in Prudhoe Bay field, including formulation of the foam, its evaluation in sand-packs, and treatments of several wells at Prudhoe Bay. It will also document long term reduction of excessive GOR (gas-oil-ratio) in hydraulically fractured wells with small impact on black oil production. Candidate selection criteria, treatment design/implementation and three case histories (with summaries of all treatments to date) will be covered along with future enhancements to treatment design. Introduction Facility constraints on handling excessive gas production have limited black oil rates at Prudhoe Bay field for a number of years. Approaches to dealing with this problem have included expansion of gas handling facilities, so that current capacity is approximately 7.5 BSCF/day. Gas-cap expansion with continuing production, cusping (shale under-runs), and propped hydraulic fractures that grow upward into a gassed-out region or close enough to the gas-oil-contact (GOC) to cause coning, continue to increase field-wide gas-oil-ratio (GOR), with concomitant negative impact on liquid rates. Increasing standoff from encroaching GOC and zone shutoff of gas cusping have been addressed with remarkable success using both cement and cross-linked polymer-gel recompletions. Attempts to use foam to address gas coning associated with GOC encroachment met with limited technical success. The short-lived treatments were judged uneconomic and were discontinued. Prior to work described in this paper, the only attempts to control excessive gas production from high GOR hydraulically fractured wells involved cyclic production or simply shutting in the well or, in some cases, side-tracking. Inability to isolate the offending zone is a major reason gas shut-off re-completions were not attempted in fractured wells. Three technical developments led us to re-evaluate the use of foam for gas shut-off. First, theoretical work on critical rates for water- and gas coning has given important insight into the types of candidates most amenable to treatment for coning problems. To briefly summarize, effective treatment of a typical matrix coning problem requires a blocking agent that extends radially many tens to hundreds of feet from the wellbore, a technically and economically daunting requirement. However, coning induced by a highly conductive vertical fracture can be controlled by sealing off the fracture/gas-zone connectivity. This can be accomplished by plugging the fracture itself, or by placing a blocking agent in matrix between the fracture and the gas source. Treatment volume for effective gas shutoff is expected to thus be much smaller/more economical than that required to treat a matrix problem. Furthermore, correction of a matrix coning problem is expected to increase the critical production rate prior to reoccurrence of coning by 1.5 to 5 fold, whereas correction of a fracture connection to unwanted fluid can result in an order of magnitude or more increase in the critical rate. Second, surfactants that produce an aqueous-phase foam with stability to oil saturations approaching 30-35% (based on our laboratory studies) have become available. This offers the possibility to employ indiscriminate placement of foam or foaming agent, while relying on higher oil saturations to destabilize foam that invades an oil producing interval. Third, adding appropriate water-soluble polymers has been shown to increase foam stability and strength. In addition, utilization of a polymer with cross-linkable functionality offers the further option of forming an even stronger gelled foam. These options offered the possibility of increasing treatment lifetime, and hence economics, through use of a stronger foam than had been previously available. With these advancements we believed it was now possible to attack the problem of excessive gas influx from matrix into a propped hydraulic fracture. P. 443

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractGel-Cement Combination Squeezes have been successfully used for gas shutoff applications. Coupled with coiled tubing selective placement, gels and cements exhibit a synergistic gas shutoff effect. Gels provide an indepth block to gas production by forming a crosslinked polymer network within the porous media. Cements are able to fill voids and cavities to block gas production and provide a strong near wellbore block. Thirteen treatments have been performed to date with an economic success rate of 85%. Implementation of the technology required the use of a well-controlled gel system, consideration of possible contamination issues and modification of current coiled tubing placement strategies.

Abstract. Ordinary concrete is four components, and the six components of green high performance concrete, more than the ordinary concrete admixture and high efficiency water reducing agent. The strength of green high performance concrete fast nondestructive testing is an important aspect of development of its application. Admixtures can improve concrete workability and improve resistance corrosion; especially it can inhibit alkali-aggregate reaction. Admixtures are paid attention to researchers in this field. Concrete water-reducing agent is admixture of the main part. In the case of keeping liquidity, it can make water consumption reduce, so the concrete strength and durability can be improved.without destroying the high performance concrete structure, through the method of nondestructive testing, can detect accurately the compressive strength.

Abstract-With wide application of the high performance concrete in Engineering, the research and application of high performance concrete admixture are attaching more and more attention by researchers. Although researches are more mature on the aspects of fly ash, slag, silica fume and other non-biological materials, the research is behindhand in the aspect of biological material such as straw ash, which contains a large amount of silica dioxide and has a certain amount of volcanic ash activity. It is considered that Heilongjiang Province as a major agricultural province, moreover, burning straw pollution is particularly serious in summer and fall. It is beneficial to manufacture straw ash high performance concrete and improve the strength and durability of the concrete. According to recent analysis on physical and chemical properties of the straw ash, it is completely feasible to improve the strength and durability of the concrete by adding straw ash to it in a reasonable method. It can be sure that, if after in-depth research, the straw ash as a concrete admixture would have a wide foreground in the future.