Study On Acid Fracturing Modification Compound Temporary Plugging Technology In Carbonate Reservoir Of Northeast Sichuan

Gas field of marine carbonate reservoir in northeast of Sichuan has the characteristics of high temperature, high pressure and fracture development. The speed of acid rock reaction in acidification transformation is fast.And large amount of acid filtration leads uniform cloth acid to be difficult, which is difficult to achieve deep acidification. So composite steering technology in acid fracturing modification is researched in the northeastern Sichuan.Papers to changxing group gas field of yuanba in the northeast of Sichuan as the main research object, the reefs and raw crumbs beach facies developed in the main of changxing group reservoir. According to yuanba region changxing group rock’s physical property analysis results: the reef facies reservoir of changxing porosity of 0.23% ~ 24.65%, average4.0%;Permeability is 0.0028~1720.7187×10-3μm2.Largest connected pore throat radius is small, the main distribution is between 0 and 1 μm. The mainly three types of reservoir space of changxing group in Yuanba is pore, cave and fracture, and horizontal seam, inclined seam and vertical fractures in reservoir is developed, mostly is half a pack or open the seam. Crack width in Changxing group is mostly in 1 mm or so, but in the individual well, there is a big loss. Changxing group reservoir has no water sensitivity and susceptibility of weak alkali(pH10.5) critical, strong stress sensitivity characteristics.Yuanba changxing group belongs to the reef body region of lithologic trap gas reservoir, the buried depth of gas reservoir is large(6200~7200m),and the gas rate is high. On the whole, the gas reservoir has normal temperature, normal pressure,and high containing of hydrogen sulfide, carbon dioxide. The gas reservoir is gas drive gas reservoir gas or local water drive.According to the sample tests in yuanba region, marine strata of rock tensile strength is between 0.71 and 5.09 MPa, average 2.90 MPa.Formation as a whole elastic modulus distribution range between 7.11 and 32.81 GPa, an average of 26.44 GPa; Poisson’s ratio range between 0.20 and 0.47, with an average of 0.26; The compressive strength distribution under the geological conditions range from 116.94 to 426.32 MPa, average 225.81 MPa; Tensile strength distribution range from 0.08 to 10.04 MPa, average5.24 MPa.Changxing group average maximum horizontal in-situ stress is in 2.90~3.36 MPa/100 m, average minimum horizontal in-situ stress in 2.01~2.21MPa/100 m.In-situ stress state of main performance is a typical strike-slip stress model.According to the characteristics of changxing group gas reservoir in yuanba region and the usage of well completion production tubing, the performance of high temperature gelling acid and high temperature fracturing fluid is evaluated. Developing a high temperature and high pressure acidic temporary plugging device, optimizing the temporary plugging fiber and temporary plugging particles, operating the cracks with different sizes composite temporary plugging technology researching, finally, the final design formed a more perfect acid composite steering technology in fracturing modification in northeast of Sichuan by the field application analysis of acid and compound temporary plugging technology.Research results show that the reef facies gas reservoir of changxing group is pore type or fracture-pore type. And reservoir is given priority to Ⅲ type reservoir, a small amount of Ⅰ, Ⅱ reservoir. The development of high temperature and high pressure acidic temporary plugging meter can well simulate the 0~6 mm formation fracture, temporary plug fracture, evaluate acidification and blockage effect. Fiber temporary plugging agent effect is not ideal, so optimizing the fiber and granular composite temporary plugging agent which can be in different size 10 MPa pressure plugging fracture, and it can be dissolved by acid quickly in the design time.Acidizing field test in carbonate reservoir of Yuanba changxing group,which is through a variety of means such as well test analysis, production data analysis, construction of the pressure curve fitting analysis, conducting a comprehensive evaluation, is to improve the technology of carbonate reservoir acidification in changxing group of yuanba.Take the YB29-2 Well in field application, the first level after the temporary plugging fluid into the ground pressure increased by 19 to 26 MPa, production times after acidification reached 3.33.