Periphery Screenout Fracturing Technique

Screenout fracturing is a special fractuing method which distinguished with conventional hydraulic fracturing. It can control fracture geometry in some extent to get "wide and short fracture", thus to meet the special need of stimulation treatment for mediate and/or high permeability sand reserviors.Periphery Screenout (PSO) Fracturing is a new fracturing method proposed in this dissertation. It belongs to the same technical domain with Tip Screenout (ISO) Fracturing. The two methods have both colse links and strict distictions.PSO Fracturing is the development of TSO Fracturing.In whole, the study of this dissertation should be ranked in the domain of "practical technique study", but a lot of theoretical problems are also concerned with. For PSO or TSO fracturing, many theoretical problems havn't been studied but this papper,so, some of the conclusions also have the room for further discussion and modification.Four parts are included in this dissertation. The first is about the mechanism of fracture periphery screenout and the limmitation of sand bridge to fracture extention. The second concerned mainly with the rule of fracture development before and after screenout process begins. The third anlysed PSO fracturing plan designment method which differ with conventional fracturing, including fluid and proppant slection, the designment of screenout moment and the limitation of screenouting period, the distribution of pad and slury, and so on. The fourth is about the application of PSO fracturing technique to oilfield. In this part, the theoretical foundation of two monitoring method of screenout process is analysed, the mainly applicationdomain of this techanique and some experiment examples are discussed. The primary contributions of this papper are:(1) "Periphery Screenout (PSO) Fracturing" is first proposed in this papper and its theory system frame is surgested. Some of them also suit for ISO Fracturing.(2) The mechanism of fracture periphery screenout is first studied in this papper. On the basis, some technical conditions for periphery screenout sand bridge is summarised.(3) The limmitation mechanism of sand bridge to fracture extention is first studied in this papper. On the basis, some engineering measures to enhance sand bridge's limmitation effect on fracture extention are suegested.(4) The optimization method of pad and slury used in conventional fracturing was introduced in PSO fracturing design, thus simplized calculation programme and improved PSO fracturing design method.(5) A new method named "fracturing vibration wave method" was introduced to monitor screenout process, it woked in coordination with conventional "pressure monitoring method" can get more and better monitoring results for screenout fracturing.