Research And Application Of Acid Fracturing Technology Of Crosslinked Acid Fluid On Carbonate Reservoirs

Acid fracturing technology is not only the main one to increase oil and gas production and make stable yields in carbonate reservoirs but an important measure in oil and gas exploration and exploitation. In recent years, deeply or over deeply-buried carbonate reservoirs were discovered and developed one after another through exploration in the west of China, whose reservoirs are very heterogeneous and pure carbonate rock with high temperatures. Because a few wells put into production naturally, acid fracturing technology has already become the important measure before production.Some necessary applied technologies are formed in Jing Bian gas field in accordance with the characteristics of low permeability, low pressure and low production in Lower Paleozoic dolomite reservoirs. As the field put into production progressively, favorable areas decreased, test yield tends to decrease by degrees, related technologies to increase production have not good effects, so the research and application of proppant-carried acid fracturing technology with new acid- crosslinkedacid are proposed.On the basis of many laboratory experiments and research on mechanism of the acid fracturing models, the system of crosslinked acid is developed and researched, and the plan of acid fracturing is improved in the paper. The proppant-carried acid fracturing technology has been tested in the gas field, which fills in the gaps of proppant-carried acid fracturing technology. The main recognitions and results are as following:1 .Theoretical results of crosslinked acid system:The prescription of mud thickener and crosslinking materials is researched and tested respectively, the main properties of crosslinked acid fluid can meet the requirement of acid fracturing, synthetic technology of the tested samples is finished(crosslinked acid is named first). The texture of crosslinked acid fluid is changed from linear to network, so that acid fluid carries proppant theoretically.2.The properties of crosslinked acid are measured and proved through experiments:The main dynamic and static properties and reaction behavior parameters of crosslinked acid are measured first time, such as the reaction behavior parameters of reaction velocity constant, reaction activation energy and reaction formulation; some properties are evaluated such as viscosity and temperature, shearing property, flow capacity of acid-etched fractures, filter loss, compatibility, property of gel breaker,...