| P reservoir of TW gas field is a typically low permeability sandstone gas reservoir. In recent years, more and more reservoirs with low permeability has been found in offshore, it’s inevitable to utilize the hydraulic fracturing as the common stimulation methods. Some difficulties has existed in hydraulic fracturing in TW gas field, such as high demand in fracturing fluid, special construction environment and poor experience, meanwhile, the limitation of fracturing technique and equipments, all of which result in the application of hydraulic fracturing has not reach expectation in TW gas field.In this thesis, aiming at the difficulties of hydraulic fracturing in P reservoir of TW gas field, all of research works have been done through data research, laboratory experiments and field application. Engineering geology, fracturing fluid, proppant, fracturing technology, and so on, have been studied. The main work and contributions that have achieved in this thesis can be summarized in the following aspects.Through analysis of geological data and laboratory experiments, P reservoir of TW gas field is a low permeability sandstone gas reservoir with high abundance, target formation is strong water sensitivity, medium alkali sensitivity and medium water block, meanwhile, a little condensate oil is output, formation temperature is 135℃.After analysis of geological characteristics of target formation, a fluid system of 0.55%HPG+1%G513-WDJ+0.5%G517-XZ+0.5%YL-11+1%KC1+0.2%YW-1+0.1%Na2CO3 +0.5%CQL-2+0.1%CJSJ-2+1%G514-SCJ+water was determined by optimization of main fluid and additive. This kind of fracturing fluid system had many advantages of good coMPatibility, high temperature resistance, shearing resistance, low filtration, low residue, high anti-swelling and low tension of gel breaker filtered fluid, which was regard as a low damage fracturing fluid system.It’s application in P formation was good, and the damage rate was only 17.7%.According to the technical investigation and the analysis of the geological characteristics of the TW gas reservoir, finally, we choose the Z-prop fused ceramic as the types of the proppant. The cost of Saint-Gobain’s proppant is low and this proppant can also satisfy the need of stimulation in the low permeability reservoir. Two types of Saint-Gobain’s proppant, which sieve mesh number are 30/50 and 20/40, both have good physical properties.What is more, the proppant can also maintain good diverting capacity under the high closure pressure so that it can be used in different processes.P reservoir of TW gas field is divided into three kinds of reservoir, fracture length, fracture conductivity and construction parameters has been optimized. All the optimization design provide a reference for Single well optimization design.Through the coMParison and analysis of both workboat and platform fracturing, it is considered that the two fracturing methods have their own advantages and disadvantages. Based on surveying drain fluid technology home and abroad, we acknowledge that the method of liquid nitrogen, gas lift valve gas lift, gas lift could benefit fracturing fluid flowback under the limitation of exceptive construction offshore low permeability environment.The field application of hydraulic fracturing in well A6 was very successful, all the process worked well. The fracturing fluid was good crosslinking, good carrier performance, good high temperature resistance performance, which satisfied the demand of construction. Total flowback volume was 175.6m3, flowback rate is 82.5%. The production is about 1.5×104m3/d-2×104m3/d. Meanwhile, well A6 is the first time to utilize the idea of Well completion-Hydraulic fracturing-Production, which is a beneficial exploration. |
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