Key Safe Drilling Technology and Application of Highly Deviated Well for High-Pressure Gas Reservoirs in Western the Right Bank of the Amu Darya River

The west of Amu Darya Right Bank has complex geologic conditions and active shallow groundwater. The middlesalt-gypsum layers of Kemalian stage contain lenticular high-pressure saline aquifer, and the lower Kalov-Oxfordian reservoir develops high-pressure gas layer and high sulfur content. Complexities such as water invasion, gas kick, wellbore instability and leakage are prone to occur during drilling. The integrated application of suitable characteristic technologies such as wellbore structure optimization technology, strong inhibitive anti-sloughing drilling fluid technology and creep-resistant salt layer drilling fluid technology has effectively solved the problem of safe drilling of highly deviated wells in high-pressure gas reservoirs. This paper focuses on the optimization design of wellbore structure, drilling fluid technology for salt gypsum layer and safe drilling technology for salt gypsum layer. The subject ideas of several technologies in this paper are based on the properties of salt-gypsum layer and wellbore stability. This paper optimizes the seal-point, forms the three-section drilling program. The strong inhibition and anti-collapse drilling fluid system for upper layer and the polysulfonate under saturated-saturated brine drilling fluid system for salt-gypsum layer, and the salt-gypsum layer safe drilling technology are optimized. The integrated application of the above technologies reduces the occurrence of serious drilling fluid leakage, casing collapse and other complexities. The salt-gypsum layers are successfully drilled, and the cementing quality is guaranteed, the risks of safe drilling of highly deviated wells for high-pressure gas reservoirs in this area are effectively reduced, which provides reference for similar reservoirs.