Sand Offshore Gas Field Study Design Criteria Fine Defense

The sand control of offshore gas fields is different from that of ashore gas fields. Limited platform spaces, high investment and high risk requires that the sand production rate must be controlled in a confined range. Once the confined range is exceeded, it will cause great economic losses. So, as to the sand control of offshore productive gas fields, it is better to adopt a conservative sand control design criterion.Currently, people all around the world mainly design the sand retention accuracy according to the Saucier theory, however, the actual production indicates that this criterion is not fit for all the oil and gas fields sand retention accuracy design, but generally only for conventional oil formations and ashore gas bearing formations. The sand retention accuracy design for offshore gas fields is still on the primary stage. Combining the two parallel concepts "moderate sand control" and "conventional sand control", we put forward the concept "delicate sand control". Its technological key point is the design of sand retention accuracy.In this paper, we conduct research on the sand retention accuracy for advanced high quality screen, the goal of which is to come up with a criterion for sand retention accuracy design that meet the delicate sand control requirements-guarantee the production as well as not to cause ground and downhole equipments corrosion.In this paper, we adopt the lab sand production-sand control simulation experiment method. Aiming at several offshore gas fields, such as PANYU30-1/PANYU34-1/PANYU35-2and LIUHUA19-5, we use the actual formation cores to simulate the sand production conditions of wells with advanced high quality screen under different daily production and screen mesh. Eventually, we synthesize and analyze the experiment results, and put forward the offshore gas field sand retention accuracy design criterion.We get the following conclusions though the research above.(1) We get the primitive offshore productive gas field delicate sand control criterion by means of analysis of the experiment results and field tests;(2) As to the offshore gas fields, we recommend80mesh(the screen aperture diameter is177um) as the optimal sand retention accuracy for medium sand formation;140mesh(the screen aperture diameter is105um) is recommended for fine sand formation and170mesh(the screen aperture diameter is88um) is suitable for silty sand formation;(3) The design criterion has been verified in PANYU30-1gas field successfully. All the nine production wells of the gas field are free of platform erosion and downhole equipments erosion caused by sand production, which indicate that the delicate sand control design criterion can guarantee high production of the production wells as well as the validity of sand control.In this paper, we prove the necessity of offshore gas field delicate sand control and we also determine the relevant design criterion, which was verified by actual production. This criterion supplement the blank of offshore gas field sand control accuracy design, and it provides instructions for sand control design of gas field completion.